MASARYK
UNIVERSITY
FACULTYOF SCIENCE
DEPARTMENTOF CHEMISTRY
LASER-MATTERINTERACTIONAS
A KEY PROCESS FOR SAMPLING
BY LASER ABLATION
HABILITATION THESIS
MARK~TAHOLA BRNO 2024
Science and everyday life cannot and should not be separated.
Rosalind Elsie Franklin
At this point, I would like to thank those who made this habilitation thesis possible. I would
like to start with my family,as they occupy a central position in my life. Family may seem like
an obstacle to many in a scientific career, but on the other hand, it can be a great asset. My
family taught me to solve unexpected problems immediately, manage time, and work
efficiently. They also taught me patience and how to find joy in seemingly small and
insignificant moments inlife. I thankmy husband, David, who has always been and will always
be my support; my children, Monika and Šimon, who constantlyteach me what is important in
life. I thank my parents for the care they gave me and unwavering belief in me. My dad, who is
unfortunately no longer here, would be extremely proud of me. I must also mention our dog,
Dusty, a constant reminder that every day can be filled with happiness, yet also with
responsibility for others.
The fact that I have reached this point in my scientific career is mainly due to my colleagues at
the Masaryk University,whom I consider to be my second family. I am particularlygrateful to
prof. Viktor Kanický, who was and is a great role model for me both in terms of science and
humanity. I am grateful to prof. Vítězslav Otruba, an excellent scientist and the supervisor of
my diploma anddoctoral theses. Special thanks go to mylong-time colleague andfriend,Tomáš
Vaculovič,who is a great support for me every day. I thankmy other colleagues,Karel Novotný
and Aleš Hrdlička, who constantly surprise me with their patience and composure in solving
problems. I also thank other colleagues, Lucie Šimoníková, Michaela Kuchynka, Veronika
Faltusová and others. I would like to thank my colleague Jakub Ondráček form CAS for
devoting his time to unconventional connection of aerosol devices and laser ablation.
Sport forms an integral part of my life, providing physical and mental balance. I am grateful to
my friends, manyof whom are alsocolleagues,for creatinganenvironment that fosters sporting
achievements and life-enriching experiences. Their support motivates me to train, especially
for our cycling adventures.
This habilitation thesis contains 12 relatedpublications,all focused on the use of laser ablation
as a sampling method for inductivelycoupled plasma mass spectrometry.It presents the range
of applications for laser ablation inductivelycoupled plasma mass spectrometry (LA-ICP-MS)
technique and provides a detailed analysis of laser ablation parameters and their influence on
laser-matter interactionand subsequent aerosol formation.The qualityof this aerosol is crucial
for the accuracy and precision of the analysis. Parameters such as wavelength, laser pulse
duration, fluence or choice of ablation mode are discussed. The thesis also highlights the
significance of the sample's physical, chemical, and surface properties. Additionally, it
discusses various methods for studying the processes that occur during the interaction of the
laser pulse with the sample. These methods include the study of ablation craters, the
characterization of the generated aerosol, in particular the determination of the particle size
distribution and the time-resolved signal processing of the monitored isotopes.
1 Introduction ...................................................................................................................... 6
1.1 Structure of the thesis.................................................................................................6
1.2 Summary of publications used in the thesis............................................................... 7
2 Laser ablation ................................................................................................................. 10
2.1 A sampling tool for ICP-MS.................................................................................... 10
2.2 If laser ablation were the ideal sampling method..................................................... 15
2.3 Fractionation............................................................................................................. 15
2.4 How to diagnose the laser-sample interaction?........................................................ 16
2.4.1 Characterization of the ablation crater ............................................................. 17
2.4.2 Characterization of the generated aerosol ........................................................ 19
2.4.3 Processing of the time-resolved ICP-MS signal............................................... 22
3 Parameters affecting the laser ablation process .......................................................... 23
3.1 Laser wavelength...................................................................................................... 23
3.2 Laser pulse duration ................................................................................................. 25
3.3 Laser fluence ............................................................................................................ 28
3.4 Ablation mode and spot size .................................................................................... 30
3.5 Sample matrix........................................................................................................... 33
3.6 Sample surface ......................................................................................................... 38
4 Conclusion and outlook..................................................................................................43
5 References ....................................................................................................................... 45
6 Abbreviations.................................................................................................................. 50
7 Attachment...................................................................................................................... 51
1 Introduction
Inductivelycoupled plasma mass spectrometry(ICP-MS) is a widespread method in inorganic
analysis allowingthe determinationof elements intrace andultra-trace concentrations.It is also
popular for the possibility of accurate determination of isotope ratios, which are used, for
example, in geochronology, bioarchaeology, food science, biology, ecology, etc. In a typical
arrangement, samples in liquid form are introduced into the ICP-MS spectrometer. This is
advantageous for initially liquid samples, such as water. However, for solid samples, this
necessitates a precedingdigestionprocess,limitingthe analysis to the determinationof the bulk
content of analytes. Laser ablation (LA) offers an alternative samplingmethod, expanding the
application of ICP-MS to localised analysis of very small areas on solid samples without prior
digestion.
Sampling by laser ablation operates on the principle of laser pulse interactionwith the sample
surface,removingpart of the material whichis then transported bycarrier gas to the inductively
coupled plasma. The extent and nature of this interactionare influenced by both the conditions
of the laser ablationand the sample's properties.Numerous variables canbe adjusted,including
the optimizationof laser parameters,the selectionof the ablationcell, the flow rate and type of
carrier gas, or the modification of the sample surface.
Understanding the process of laser-matter interaction enables control over various process
variables. These include efficient coupling of the laser beam to the sample, reproducible
ablation, control of the volume of material removed, minimization of preferential ablation,
achievement of stoichiometric ablation,andcontrol over the size distributionof laser-generated
particles. Gaining an overview of the complexity of laser ablation process is extremely
beneficial for optimizing the sampling conditions and the processing of the measured data,
opening the way to obtain accurate and precise results using the LA-ICP-MS technique.
1.1 Structure of the thesis
This habilitation thesis is a collectionof 12 papers that deal with the fundamental study of the
laser beam interactionwiththe surface of a solidsample,and its consequences for the formation
of an aerosol suitable for dosing into ICP-MS. The papers have been produced continuously
throughout my scientific career, reflecting my enduring interest in this area. It aims to
consolidate essential knowledge about laser ablation sampling and its various applications,
while also investigating the parameters that influence the ablation process. Seemingly minor
insights can contribute significantly to our understanding of the physical and chemical
processes involved in using a laser as a sampling tool for mass spectrometry.
The initial sections of this work provide a comprehensive overview of laser ablationsampling,
detailing its fundamental principles and potential applications 1-3
. The core of this thesis is
devoted to examining specific aspects that influence the ablation process, including the laser
wavelength 4
, pulse duration 4
, pulse energy 5, 6
, ablationmode 7, 8
, as well as the matrix 8-11
and
surface properties of the sample 5, 6, 12
.To facilitate understandingof these core topics,the thesis
also includes a summaryof techniques used to diagnose the interactionprocesses betweenlaser
radiationandthe sample. This involves detailedcharacterizationof ablationcraters 5-11
,analysis
of the aerosol generated by laser ablation 4-12
, and the processing of LA-ICP-MS signals 1-8, 11,
12
.
This habilitationthesis not only collects a range of research findings but also places them in a
wider scientific context,includingreferences to the work of other researchgroups dealingwith
similar research topics. The primary focus of this work is on nanosecond laser ablation, in
accordance with the capabilities of our laboratory,thus representinga specific subsectionof the
extensive domain of LA-ICP-MS.
For clarity and easy orientation in cited works, my contributions selected for the habilitation
thesis are listedas the first 12 publications and are highlightedin blue and bold withinthe text.
1.2 Summary of publications used in the thesis
So far, I have published 47 papers (according to the WOS database), 42 of which are in peerreviewedjournals
and 5 inconference proceedings.Amongthese 42 publications,I am the main
or corresponding author for 15 of them. Due to the focus of my habilitation thesis, I have
selected 12 publications and provide an overview that summarizes my contributions to them.
This summary pays particular attention to aspects such as experimental work, student
supervision, manuscript preparation, and research direction.
1. Wertich,V.*, Kubeš, M., Leichmann,J., Holá, M., Haifler,J., Mozola,J., Hršelová, P., Jaroš,
M., Trace element signatures of uraninite controlled by fluid-rock interactions: A case study
from the Eastern Moldanubicum (Bohemian Massif), Journal of Geochemical Exploration.
2022, 243, 107111. DOI 10.1016/j.gexplo.2022.107111 (IF 3.9)
Contribution: Experimental work, evaluation of data, participation in manuscript writing
(Experimental work 30 %, Supervision 10 %, Manuscript 20 %, Research direction 20 %)
2. Holá, M., Kalvoda, J.*, Nováková, H., Škoda, R., Kanický, Possibilities of LA-ICP-MS
technique for the spatial elemental analysis of the recent fish scales: Line scan vs. depth
profiling, Applied Surface Science. 2011, 257(6), 1932-1940. DOI
10.1016/j.apsusc.2010.09.029 (IF 6.7)
Contribution: Designof experiments, experimental work, evaluationof data, participation in manuscript writing
(Experimental work 50 %, Supervision 60 %, Manuscript 40 %, Research direction 30 %)
3. Holá,M., Novotný, K.*, Dobeš, J., Krempl,I.,Wertich,V.,Mozola,J., Kubeš, M.,Faltusová,
V., Leichmann, J., Kanický, Dual imaging of uranium ore by Laser Ablation Inductively
Coupled Plasma Mass SpectrometryandLaser InducedBreakdownSpectroscopy, Spectrochim.
Acta B. 2021, 186, 106312. DOI 10.1016/j.sab.2021.106312 (IF 3.3)
Contribution: Designof experiments, experimental work, evaluationof data, participation in manuscript writing
(Experimental work 30 %, Supervision 50 %, Manuscript 30 %, Research direction 50 %)
4. Možná, V., Pisonero, J.*, Holá, M., Kanický, V., Günther, D., Quantitative analysis of Febased
samples using ultraviolet nanosecond and femtosecond laser ablation-ICP-MS, J. Anal.
At. Spectrom. 2006, 21(11), 1194–1201. DOI 10.1039/b606988f (IF 3.4)
Contribution: Supervision, consultation, participation in manuscript writing
(Experimental work -, Supervision 30 %, Manuscript 15 %, Research direction 20 %)
5. Holá, M., Salajková, Z., Hrdlička, A., Pořízka, P., Novotný, K., Čelko, L., Šperka, P.,
Prochazka, D., Novotný, J., Modlitbová, P., Kanický, Kaiser, J., Feasibility of NanoparticleEnhanced
Laser Ablation Inductively Coupled Plasma Mass Spectrometry. Anal. Chem. 2018,
90(20), 11820–11826. DOI 10.1021/acs.analchem.8b01197 (IF 7.4)
Contribution: Design of experiments, experimental work, evaluation of data, manuscript writing
(Experimental work 50 %, Supervision 60 %, Manuscript 80 %, Research direction 70 %)
6. Salajková, Z.*, Holá, M., Prochazka, D., Ondráček, J., Pavliňák, D., Čelko, L., Gregar, F.,
Šperka, P., Pořízka, P., Kanický, De Giacomo, A., Kaiser, J., Influence of sample surface
topography on laser ablation process, Talanta. 2021, 222, 121512. DOI
10.1016/j.talanta.2020.121512 (IF 6.1)
Contribution: Design of experiments, experimental work, evaluation of data, manuscript writing
(Experimental work 40 %, Supervision 60 %, Manuscript 80 %, Research direction 80 %)
7. Nováková, H., Holá, M.*, Vojtíšek-Lom,M., Ondráček, J., Kanický, V., Online monitoring
of nanoparticles formedduringnanosecondlaser ablation,Spectrochim.ActaB. 2016, 125, 52–
60. DOI 10.1016/j.sab.2016.09.017 (IF 3.3)
Contribution: Design of experiments, experimental work, evaluation of data, manuscript writing
(Experimental work 50 %, Supervision 80 %, Manuscript 70 %, Research direction 90 %)
8. Holá, M.*, Ondráček, J., Nováková, H., Vojtíšek-Lom,M., Hadravová, R., Kanický, V., The
influence of material properties onhighly time resolvedparticle formationfor nanosecondlaser
ablation, Spectrochim. Acta B. 2018, 148, 193–204, DOI 10.1016/j.sab.2018.07.001 (IF 3.3)
Contribution: Design of experiments, experimental work, evaluation of data, manuscript writing
(Experimental work 60 %, Supervision 80 %, Manuscript 80 %, Research direction 90 %)
9. Holá,M.*, Konečná, V.,Mikuška, P., Kaiser, J., Kanický, V., Influence of physical properties
and chemical compositionof sample onformationof aerosol particles generatedbynanosecond
laser ablation at 213 nm, Spectrochim. Acta B. 2010, 65(1), 51–60. DOI
10.1016/j.sab.2009.11.003 (IF 3.3)
Contribution: Design of experiments, experimental work, evaluation of data, manuscript writing
(Experimental work 60 %, Supervision 80 %, Manuscript 80 %, Research direction 90 %)
10. Holá,M.*, Konečná, V., Mikuška, P., Kaiser, J.*, Páleníková,K., Průša, S., Hanzlíková, R.,
Kanický, V., Study of aerosols generated by 213 nm laser ablation of cobalt-cemented hard
metals, J. Anal. At. Spectrom. 2008, 23(10), 1341–1349. DOI 10.1039/B802906G (IF 3.4)
Contribution: Design of experiments, experimental work, evaluation of data, manuscript writing
(Experimental work 60 %, Supervision 80 %, Manuscript 80 %, Research direction 90 %)
11. Holá, M.*, Mikuška, P., Hanzlíková, R., Kaiser, J., Kanický, V., Tungsten carbide
precursors as an example for influence of a binder on the particle formationin the nanosecond
laser ablation of powdered materials, Talanta. 2010, 80(5), 1862–1867. DOI
10.1016/j.talanta.2009.10.035 (IF 6.1)
Contribution: Design of experiments, experimental work, evaluation of data, manuscript writing
(Experimental work 70 %, Supervision 80 %, Manuscript 80 %, Research direction 80 %)
12. Holá, M., Salajková, Z., Hrdlička, A.*, M., Ondráček, J., Novotný, K., Pavliňák, D.,
Vojtíšek-Lom, M., Čelko, L., Pořízka, P., Kanický, V., Prochazka, D., Novotný, J., Kaiser, J.,
The effect of nanoparticle presence on aerosol formation during nanoparticle-enhanced laser
ablation inductively coupled plasma mass spectrometry, J. Anal. At. Spectrom. 2020, 35(12),
2893-2900. DOI 10.1039/d0ja00324g (IF 3.4)
Contribution: Design of experiments, experimental work, evaluation of data, manuscript writing
(Experimental work 50 %, Supervision 50 %, Manuscript 80 %, Research direction 90 %)
2 Laser ablation
2.1 A sampling tool for ICP-MS
Laser ablation, as an alternative sampling technique for Inductively Coupled Plasma Mass
Spectrometry, finds applications across a wide range of scientific fields. Its basic principle
involves irradiating the sample with a laser to induce an ablation process, resulting in the
removal of a small amount of material. This ablated material is then transported to the
inductively coupled plasma (ICP), where it is vaporized, atomized, and ionized. The resulting
ions are subsequently analysed and detected in a mass spectrometer and signal of individual
isotopes is recorded 13, 14
. Different approaches to sample analysis can be taken depending on
the specific analytical requirements. According to the Web of Science database, most
applications are relatedto the geological sciences, with 12,500 out of a total of 17,000 articles
pertaining to the geological applications of LA-ICP-MS.
One such approach is spot ablation,where the pulsed laser repeatedlyremoves material from a
single spot. It's essential to monitor data consistency of the time-resolved LA-ICP-MS signal:
any sharp drop or rise in the value of the observed isotope may indicate the presence of an
impurity or inhomogeneity, potentially biasing the results. Figure 1 presents an example of a
time-resolved signal for isotopes measured in an uraninite mineral sample, achieved using
a nanosecond (ns) laser with a wavelength of 213 nm, a beam diameter of 50 µm, a fluence of
9 J cm²,
and a laser repetition rate of 10 Hz. The data in Figure 1a indicate minimal risk of
contaminationat the ablation site from fluid or mineral inclusions hidden beneath the surface.
Conversely, isotopic records in Figure 1b that varies from the described correct isotopic
recordings hint at the presence of a mineral or fluid inclusion. Such inclusions would
significantly alter the geochemical composition of the measured uraninite, and therefore, the
data must be excluded from the overall recorded data set 1
.
Fig. 1. a) LA-ICP-MS spot analysis record of uraninite displaying the correct shape; and b) record of
uraninite spot analysis contaminated by chalcopyrite mineral inclusions hidden beneath the surface 1.
As can be seen from the description of spot ablation, the laser beam gradually penetrates the
depth of the analysed sample. This can be advantageously used for monitoring changes in the
sample's composition at various depths – termed depth profiling.
Depth profiling is another technique employed in LA-ICP-MS. This method also involves
applying laser pulses to a single spot, but instead of targeting just one layer, it monitors the
evolution of the sample's
composition over time,
revealing compositional
changes at various depths.
By knowing the ablationrate
(the amount of material
removed per pulse), the
thickness of individual
layers can be defined 15
. For
instance, in metallurgical
applications, depth profiling
can accuratelydetermine the
thickness and composition
of layers down to
nanometres, particularly
when using a femtosecond
laser 16
. In natural samples,
such as bones and teeth,
depth profiling can provide
insights into an organism's evolutionor exposure to various factors. An example is the study of
otoliths, where depth profiling is a microchemical technique revealing life history patterns in
fish 17
. Fish scales,as another bony structure,can be similarlyanalysed,althoughtheir complex
structure makes this less common. Nevertheless,scale analysis offers a non-lethal approachthat
is valuable for studying water contaminationand migrationpatterns throughout the life of fish.
Figure 2 shows a dorsal view of the scale structure and the location of the performed LA-ICPMS
analyses 2
. Depth profiling results of the anterior part scales from common carp (Cyprinus
carpio) show a concentration gradient of selected elements throughout the scale's thickness,
with a clear distinction between the external hydroxyapatite layer and the basal collagen plate
(Figure 3a – 3c). It was also discovered that the scale surface can accumulate heavy metals,
effectivelypreventing their penetration into the deeper structure (Figure 3c - 3d) 2
. Generally,
the LA-ICP-MS methodranks among the depthprofilingtechniques,which have the advantage
of simple sample preparation(similar to the technique of Glow discharge spectrometry 18
). In
Fig. 2. Dorsal view of the fish scale of the common carp with
marked posterior and anterior part. The anterior part, divided in
the anterior and lateral fields, is covered by other fish scales while
the posterior field is in contact with water; Marked trajectories for
LA-ICP-MS and EMP analysis 2
.
contrast, commonly used microscopic methods require a cross-section to be made first, which
can be technically and time-consuming.
Fig. 3. LA-ICP-MS depth profiling on the posterior part of the fish scale (common carp) for following
pairs of isotopes: a) 42Ca and 12C; b) 31P and 26Mg; c) 86Sr and 66Zn; d) 208Pb and 56Fe. Laser wavelength
of 213 nm, 100 µm spot size, repetition rate of 4 Hz, fluence of 3.5 J cm-2 2
.
The applicationof a specific number of pulses to one spot allows for the determinationof either
the average composition of a sample or its depth profile. An alternative approach involves
performing a linear scan across a selected part of the sample. This technique serves various
purposes: it can determine the average composition of a larger sample area, such as a specific
zone 19
, or it can be employed to identify variations in element distribution across different
zones. This is particularly beneficial for tasks like determining mineral zonation 20
, assessing
element concentrations in growth lines (such as tree rings 21
, otoliths 22
, urinary stones 23
, etc.),
detecting impurities or heterogeneities in industrial products 24, 25
, defining archaeological
artefacts 26
or other analyses. The parameters defininga linear scan are similar tothose for spot
ablation: spot size, number of pulses, repetitionrate and fluence. A key additional parameter is
the scan speed. This speed, combined with the other parameters, dictates the degree of pulse
overlap, spatial resolution, and the overall duration of the analysis.
The use of line scans in LA-ICP-MS provides valuable insights, again, with fish scale analysis
serving as a pertinent example 2
. Performing a line scan across the entire fish scale,
perpendicular tothe growth rings as illustrated in Figure 2, enables analysis of both the anterior
part, which is covered by other scales, and the posterior part, which is in direct contact with the
water. This type of analysis,as detailedin Table 1, reveals a distinct distributionof elements in
the two regions.
Specifically,certaintrace metals like Zn and Mn, as well as matrixelements such as Ca and P,
and predominant cationsubstituents like Mg and Sr, were found to be more concentratedin the
posterior part. This discrepancy is largely attributed to the higher prevalence of the mineral
phase in the posterior region, which facilitates increased substitution and vacancy filling.
Additionally, certain trace metal elements, namely Fe and Pb, exhibited symmetrical
distributions with elevated levels near the scale's periphery. Such patterns likely reflect
variations in diet or environmental pollution exposures over time.
Table 1 LA-ICP-MS line scan analysis of fish scale; average values for each region 2
.
The applicationof multiple line scans coveringselectedarea of a sample is used for the imaging
method. In this approach, a specifiedarea on the sample surface is scanned using parallel lines,
where the combination of spot size, line spacing, scan speed, and repetition rate defines the
spatial resolution of the resulting elemental/isotopic maps and the time of analysis. However,
producing a high-quality image is not without challenges. Common artifacts like blur, smear,
aliasing, and noise can compromise the integrity of the image. Various studies and techniques
have been developed to reduce or eliminate these undesired effects, ensuring clearer and more
accurate visual representations of elemental distributions 27
.
Detailed imaging with LA-ICP-MS is very popular for biological applications 28, 29
,
characterization of steels 30, 31
or alloys 32
, archaeology 33
, geological applications 34, 35
, and
others.An example is the analysis in the uraninite mineral zone 3
. A specific area of 2 × 3 mm
was methodically analysed usinga 213 nm laser. For the line scans, parameters suchas a 20 μm
spot diameter,a scanspeed of 20 μm s-1
, a 10 Hz repetitionrate,and a fluence of 10 J cm-2
were
chosen,achievinga spatial resolutionof 20 μm. The scanrate of 20 μm s-1
was purposelychosen
to matchthe dwell time (1 s) to the time required to traverse the diameter of the ablationcrater
(20 μm), effectively preventing any smearing of the LA-Q-ICP-MS signal along the x-axis.
The visualization of individual isotopes offers invaluable insights, particularly evident when
examining lead isotopes. Lead presents an interesting isotopic spectrum, with non-radiogenic
204
Pb coexistingwith radiogenic isotopes of 206
Pb and 207
Pb, which originate from the decay of
238
U and 235
U respectively.Additionally, 208
Pb is a product of 232
Th's radiogenic decay. Nonradiogenic
lead 204
Pb is not related exclusively to the structure of uraninite but also forms
isolated clusters, likely as compounds with sulphur or selenium, while radiogenic isotopes of
lead also copy their parent nuclides. Therefore, the most abundant and homogeneous is
representedby the isotope 206
Pb as the decay product of the isotope 238
U (relative abundance of
99.274%), which is the main component of uraninite. The heterogenous distribution of 207
Pb
and even more apparently 208
Pb within uraninite aggregates, considered to have originated in
one-time period,is worth mentioningdue to usage of lead isotope ratios for radiometric dating.
In this context, intra-grainscale isotopic variations within fresh uraninite aggregates, showing
no visible effect of post-crystallizationalteration. All isotopic maps are presented in Figure 4.
Fig. 4. Photography of analysed sample area (1) and distribution of selected isotopes in uraninite
obtained by LA-ICP-MS. Normalised intensities in cps, blue colour as minimum, red as maximum 3.
2.2 If laser ablation were the ideal sampling method...
Laser ablation,as an alternative samplingtechnique for ICP-MS, offers numerous benefits over
the conventional nebulization of liquid samples. This technique provides many significant
advantages, makingit anideal tool for accurate andefficient materialanalysis. The most notable
advantage is the minimization of sample preparation requirements. Because laser ablation
allows for direct sampling of solid samples into ICP-MS, the need to convert samples into
solution is eliminated. This significantly saves time, as complex preparation processes are
replaced by almost instantaneous analysis. Furthermore, it eliminates the need for chemicals,
making the process more efficient while reducing the risk of contamination or sample loss
during preparation. Moreover, the focused laser beam permits highly localised and spatially
resolved analyses, enabling detailed examination of sample heterogeneity on a microscopic
scale. Additionally, the combination of laser ablation and ICP-MS is conservative in terms of
sample usage, consuming only a minimal quantity of material. This aspect is crucial when
dealing with rare or limitedsamples. In an ideal scenario,the material released by laser pulses
accurately reflects the composition of the original sample.
In summary, under ideal conditions,laserablation serves as a unique,rapid,efficient,andhighly
accurate method for analysing a wide range of materials for scientific and industrial purposes.
However, achieving these ideal conditions is not straightforward, and LA-ICP-MS analysis is
usually complicated by factors such as fractionation or matrix effects.
2.3 Fractionation
In fact, the laser-matter interaction is a complex process depending on both the laser ablation
conditions (pulse duration,wavelength,repetitionrate,pulse energy,spot size) and the sample's
physical and chemical properties 4, 8, 9, 11, 36, 37
. Generally, the laser beam can interact with the
material in two basic ways – thermal (photothermal) and non-thermal (photochemical) 38, 39
.
For longer pulses (nanosecond ablation), heat conduction, melting, evaporation, and plasma
formationare the dominant processes.The energy of the laser is absorbedby the sample surface
and forms a temperature field due to the heat conduction. Depending on the achieved
temperature, the material melts, evaporates, or is transferred to a plasma state. Laser ablation
parameters, especiallypulse duration andpulse energy,affect the proportionalityof evaporation
and sputtering of the melt as the main processes of nanosecond laser ablation 40
. The physical
and chemical properties of the sample can significantly influence the laser energy absorption
(absorption coefficient for the specific wavelength), the heat transfer (thermal conductivity) 8,
9, 41, 42
and degree of plasma shielding (attenuationof the incoming laser radiationby plasma).
On the other hand, the sample heating by the laser irradiation significantly modifies the optical
and thermo-physical properties,suchas surface reflectivity,electrical andthermal conductivity,
surface tension, and latent heat of vaporization 43
. Thermal and non-thermal processes create
particles of the sampled aerosol by different principles; therefore, their size distribution and
composition differ (a more detailed description of the mechanism of particle formation is
describedin Chapter 3.5). The particle size is important due to the transportationefficiencyand
its impact on vaporization, atomization, and ionization efficiency within the ICP. This insight
is key to understanding possible non-stoichiometric sampling, so-called fractionation.
In the context of argon ICP, which operates as an atmospheric pressure ion source, the process
of laser ablation samplingis likewise conducted in an environment of atmospheric pressure of
an ambient gas. In such a setting, the formation of the plasma generated by the laser at the site
of ablation is confined to a small volume, typically just a few cubic millimetres. Subsequent
expansion leads to material redeposition onto the sample substrate post the laser pulse.
Additionally,factors such as transport losses and the condensation of the plasma plume on the
ablation cell sidewalls or on sputtered particles can lead to a reduction in the efficiency of
ablation. These aspects can potentially alter the yield of the ablation process and affect the
accuracy of the elemental concentrations measured.
LA-ICP-MS is a time-resolved method that provides a transient signal corresponding to the
ablation conditions in terms of time. For spot ablation, it depends on the number of pulses
applied, i.e., the first pulse on an intact sample surface will not provide the same analytical
signal as a pulse generatedafter many repetitions. Here,thermal effects, meltingof a thin layer
of the sample,which can be graduallydepleted of more volatile components,and deepening of
the crater (higher aspect ratio) play a role.Fractionationduringanalysis can be quantifiedusing
the Fractionation Index (FI). The FI is given by the intensity of any element rationed to an
“internal standard” from the second half of the signal, divided by its intensity ratio during the
first half of the signal 44
. An example of FI calculations for 43 elements contained in the glass
standard SRM NIST610 for different laser wavelengths is shown in Chapter 3.1 in Figure 9 45
.
2.4 How to diagnose the laser-sample interaction?
To obtainhighqualityanalytical results byLA-ICP-MS,it is veryimportant to ensure controlled
sampling by laser ablation into the ICP mass spectrometer. Because the laser beam is focused
on a very small area (tens to thousands of square µm), and the sample is placed in a closed
chamber, monitoringthe qualityof laser ablationusing conventional laser system equipment is
very difficult.A microscope camera, which is part of the ablationsystem, is used for the basic
assessment of the ablation process. This can detect undesirable phenomena such as breakage,
cracking or crumbling of the sample, or, conversely, resistance to the laser beam used. For a
detaileddiagnosis of the samplingprocess, other procedures must be used typically based on:
- Characterization of the ablation crater
- Characterization of the generated aerosol
- Processing of the time-resolved ICP-MS signal
2.4.1 Characterization of the ablation crater
The depth, shape, structure, and chemical composition of an ablation crater are key indicators
of the laser-matter interaction.Analysing these parameters can precisely define the processes
involved and serve as a benchmark for 'correct' sampling with laser pulses. However, the
disadvantage of using craters to diagnose ablation processes is that they are assessed offline
after the analysis, usually once the sample has been removed from the ablation chamber.
Consequently,any adjustments to conditions for improvedsamplingare implementedonlyafter
an analysis has 'failed'.
A more stable analytical signal is produced with smaller values of the crater aspect ratio
(depth/diameter), ideally less than 1. At higher values (>5), there is ineffective removal of
material from the crater's base, resultingin a sharp decline in the time signal 46
. Factors such as
the number of pulses and fluence used caninfluence the resultant crater depth,whichalsovaries
depending on the sample material. Insights into the behaviour of the ablation process can be
gleanedfrom the shape, structure,andvolume of the ablationcrater.This allows for estimations
of the ablation rate, the degree of sample melting, or the extent of reverse condensation of
evaporated material. The amount of material released during laser ablation can be specified
from the ablationcrater volume, relative to the amount of material remainingaround the crater
as a rim.
For basic diagnostics,ablationcraters are typicallyfirst visualisedusing an optical or scanning
electron microscope (SEM). The microscope images enable the detection of undesired effects
such as cracking or large fragments being dislodged from the sample and allow for an
estimationof the meltingextent around the crater area. The next stage involves determiningthe
precise shape and volume of the ablation crater, usually using profilometric methods, either
based on the mechanical principle or more oftenon the optical basis. Consider Figure 5, where
laser ablation was executed using a ns laser at 213 nm under the following conditions: a laser
spot diameter of 100 μm, a fluence of 13 J cm−2
and a repetition rate of 10 Hz 9
. Figure 5
illustrates the ablation craters on different materials after 600 pulses. From the SEM images
(Figure 5A1, B1, C1), it is possible tosee the degree of meltingof the materials. This is evident
especially for steel sample (Figure A1) both from the structure of the ablation crater rim and
from the presence of large, deposited particles that arise directly from the melt of the sample
and are indicative of thermal effects. The optical profilometer provides a 3D model of the
craters (Figure 5A2, B2, C2) that shows the height of the rim,the character of the crater bottom,
and calculates the total volume. The most illustrative viewmaybe a representative cross-section
through the crater, where a degree of thermal effects and presumably fractionation effects in
LA-ICP-MS analysis can be diagnosed from the elevated crater rim or the molten crater bottom
(Figure 5A3, B3, C3) 9
.
Fig. 5. SEM (1) and optical micrograph (2) of the ablation craters together with a representative crosssection
(3) on steel sample (A), tungsten carbide (B) and glass (C) using 213 nm laser ablation 9
.
Each material exhibits unique behaviour when sampled using a laser. While its inherent
properties remain constant, the variable parameters of laser ablation can be adjusted. These
include the size of the ablationcrater,the ablationmode,fluence,repetitionrate,andthe number
of applied pulses. In the process of optimizing the LA-ICP-MS method, characterising the
ablation crater is a crucial step in identifyingthe most suitable sampling conditions.The ideal
outcome is to achieve a symmetrical ablation crater, cylindrical in shape with a flat bottom,
showing no signs of melting,crumbling, or other forms of damage. Under such conditions, an
aerosol suitable for analysis by ICP-MS can be produced.
2.4.2 Characterization of the generated aerosol
The quality of generated aerosol is crucial for conductingcorrect and accurate analyses in LAICP-MS.
The purpose of laser ablation is to generate particles that match the composition of
the sample and are of a size that can be efficiently transported and vaporized in the ICP.
Knowledge of particle sizes andtheir number distributioninlaser-generatedaerosols is required
for a better understanding of non-stoichiometric effects observed with LA-ICP-MS. These
effects are commonly encompassed under the term 'fractionation', which is influenced by a
variety of factors ranging from the conditions of laser ablation to the effects in the ICP.
However, the initial step towards understanding these complex processes is to gather
information about the properties of particles generated under specific LA conditions.
Subsequently,one can examine changes inducedby transport or ICPeffects.Since aerosol study
is only feasible after particles have exitedthe ablation cell,the influence of particle transport is
invariably included. Nonetheless, theoretical models of particle formation can be developed
based on recognized patterns 43
.
Fig. 6. Visualization of collected LA particles of a) steel sample by SEM; b) glass SRM NIST610 by TEM.
Laser-generated aerosol can be studied via different offline or online techniques. Offline
methods involve collecting particles on special filters, grids, or discs for subsequent analysis.
The efficiency of sample collection can be enhanced using an electrostatic sampler 47
, or by
segregating and depositing particles on substrates according to their aerodynamic diameter,
such as with a cascade impactor 48, 49
. These offline methods not only allow for visual
determination of particle shapes and size via various microscopic methods such as Scanning
ElectronMicroscopy(SEM),TransmissionElectronMicroscopy(TEM),Electron Probe Micro
Analysis (EPMA) but also enable the study of particle composition through subsequent
a b
chemical analysis (ICP-MS, Particle-induced X-ray Emission (PIXE), etc.) of collected
material 9, 10, 47, 48, 50, 51
. The particles visualised on the filter and on the grid are shown in
Figure 6a and Figure 6b, respectively.
The stoichiometry of the ablation can be checked by bulk analyses of all particles using a
dissolution method. Furthermore, Energy Dispersive X-ray spectroscopy (EDX) enables the
acquisitionof the composition analysis of specific particles onthe filter, which is invaluable for
elucidatingfractionationprocesses 10,11,47, 51-53
.However, a major limitationof offline methods
is the inability to monitor the evolution of particle formation over time; all samples represent
the mass accumulated over the entire sampling period.
To characterise particles generatedbylaser ablation,aerosol spectrometers operatingonline are
also utilised. These devices help mitigate alterations in the aerosol structure that might occur
with offline methods, such as filter sampling. Some systems even enable simultaneous
measurement of particle size distribution(PSD) and ICP-MS signal at a high time resolution 8
.
An example of such an arrangement is presented in Figure 7. The selection of an aerosol
spectrometer typically depends on the size range of the particles beingmeasured. Nevertheless,
it is crucial to consider the detection principle of the spectrometer to prevent misinterpretation
of results, especially for non-spherical clusters 49
.
Fig. 7. Schematics of measurement set-up for laser ablation system coupled with ICP-MS and aerosol
spectrometers, Engine Exhaust Particle Sizer (EEPS), Aerodynamic particle sizer (APS) and Optical
Particle Sizer (OPS) 8
.
Various techniques are available for analysing the physical properties of aerosol particles
produced during laser ablation. These include electrostatic classifiers with particle detectors
(such as condensation particle counters or electrometers), photometric devices, and cascade
impactors for offline analysis. Each instrument offers unique advantages and has certain
limitations. For instance, the Scanning Mobility Particle Sizer (SMPS) provides excellent
particle sizing resolution but has limitations in time resolution 54, 55
. Fast Mobility Particle
Sizers (FMPS or EEPS) deliver high time resolution but have fewer particle size bins and
require calibration due to the initial unipolar electrical charging of particles 56
. Photometric
devices are user-friendly but heavily rely on the optical properties of the sampled aerosol 57
.
Cascade impactors, regarded as a standard for gravimetric analysis, provide limited size
resolution and only offer integral values over time (offline analysis) 58
.
Different techniques based on various physical principles are used to detect particle
concentration, such as Condensation Particle Counters (CPC), Optical Particle Sizers (OPS),
Optical Particle Counters (OPC),and electrometers.Particle sizing primarily employs twomain
principles: mobility in an electrostatic field (Differential MobilityAnalyzer (DMA)) 54, 55
and
aerodynamic behaviour inacceleratedflow(Aerodynamic Particle Sizer (APS)).By integrating
particle counters and sizers, a comprehensive aerosol spectrometer can be assembled. The
SMPS system is commonly used for submicrometric particle diameters (nanometres to 1 μm)
59, 60
, while APS systems measure particles in the 0.5–20 μm range. For processes with rapid
changes in particle concentration,the Fast MobilityParticle Sizer (FMPS) combines principles
of electrostatic field mobility with concentration detection via electrometers 7, 8, 61
.
It is essential tonote that different methods for PSD estimation provide complementarydata by
measuring distinct physical characteristics of particles. For instance, comparing offline
impactor techniques with DMA (SMPS) and OPC can reveal different interpretations of
agglomerated nanoparticles in laser-generated aerosol. DMA measures physical diameters
basedon mobilityinanelectrostatic field and may overestimate the volume-equivalent diameter
for porous particles,impacting accurate mass determination. Incontrast, OPC assesses particle
diameters basedon optical equivalent diameter,significantlyinfluencedbythe particles' optical
properties 57
. If the optical properties of the measured material differ from the calibration
standard (typically polystyrene latex spheres), the results can vary significantly, often
underestimating the real particle sizes 49
. Therefore, when using any aerosol instrument, the
user must be aware of the measurement method employed and consider its advantages and
limitations in interpreting the data.
It should also be noted that planning and conducting experiments to measure the size
distribution and concentration of laser-generated particles pose significant challenges. This is
particularly because the aerosol devices employed are primarily designed for measuring
aerosols in air.As a result, the flow rates of the sampled gas, along with the concentrationand
characteristics of the particles, differ considerably when these devices are adapted for use in
laser ablation. These differences necessitate careful consideration and adaptation of
experimental protocols to ensure accurate measurements in the context of laser-generated
aerosols. An illustration of the plan and implementation of such an experiment, highlighting
these specific challenges and adaptations, is demonstrated in Figure 8.
Fig. 8. From experimental planning to implementation - measurement of aerosol properties in the
Laboratory of Atomic Spectrochemistry.
2.4.3 Processing of the time-resolved ICP-MS signal
The characteristic of the time-resolved signal of the measured isotope not only mirrors the
original composition of the sample but also reflects the effects and changes that occur
throughout the LA-ICP-MS measurement process.This includesthe interactionof the laser with
the sample, the formation of solid particles, their transport, subsequent vaporization, and
ionization, as well as the behaviour of these ions in the mass analyser and their detection.
Consequently, careful processing of the measured data is crucial for achieving high-quality
analytical results.
Adetailedanalysis of the analytical signal can,for instance,identifythe degree of fractionation,
as discussed in Chapter 2.3. This fractionation can then be compensated for using specialised
evaluation software designed for LA-ICP-MS analyses 62
. The nature of the signal varies
depending on the analytical requirements and,therefore,the establishedconditions.As a result,
there will be differences in output between bulk analysis and spatially resolved analysis as
already presented in Chapter 2.1. Signal progression also reveal undesirable sample
inhomogeneities, which must be excluded from the results, as illustrated in Figure 1b.
Furthermore, signal instability, indicative of changes in conditions during the analysis, should
be corrected using a normalization method (internal standard, sum normalization…) 63
.
Currently, data processing in LA-ICP-MS is facilitated by specialised software tailored to
specific applications inthis field.This includes bothcommercial software options,suchas Iolite
(Elemental Scientific) 64
or HDIP (Teledyne Photon Machines), and software initially
developed for internal use in laboratories which has subsequently been made available to the
public such as Ilaps designed in our laboratory 65
or LAtools 66
.
3 Parameters affecting the laser ablation process
The laser-matter interaction is a complex process influenced by both the laser ablation
conditions and the physical and chemical properties of the sample. Some laser parameters are
dictated by the construction of the ablation system used (wavelength, pulse duration) and so
their variabilitybecomes strongly dependent on the available experimental setup 67
. While the
properties of samples are often challenging to alter, in some instances, modifications are
possible, such as surface treatment or the addition of a binder to powder samples. Numerous
studies have explored a varietyof laser ablation conditions andtheir combinations,contributing
significantly to the understanding and definition of the very complex processes that occur
duringlaser ablation sampling.Parameters that most affect ablationprocess are discussedinthe
following chapters.
3.1 Laser wavelength
It is generally accepted that shorter wavelengths are more suitable for LA-ICP-MS 13
due to
higher photon energies, which are efficient at breaking bonds and ionizing the solid sample.
The use of shorter wavelengths typically results in higher ablation rates and reduced
fractionation 68
. This effect is particularly noticeable when ablating minerals or transparent
glasses,where the better absorptionof shorter UV radiation comparedto longer wavelengths is
significant. With shorter wavelengths, lateral resolution can be improved, detection limits can
be lowered, and the application of LA can be expanded to different types of minerals 69
.
Comparing different laser wavelengths usually entails using distinct ablationsystems,meaning
that factors other thanjust the wavelengthmust be considered.These include variations inpulse
duration, fluence, beam profile, laser light polarization, and the volume and shape of the
ablationchamber. To isolate the influence of wavelength on the LA process, one approach is to
use a single solid-state laser source (like a 1064 nm Nd:YAG laser) and generate higher
harmonics (532 nm, 266 nm, 213 nm, 193 nm), keeping all other laser parameters constant.
Studies focusing on the effect of wavelength on LA-ICP-MS attribute the reduction in
fractionation effects with shorter wavelengths to the PSD. When applied to glass reference
materials, a higher fraction of smaller particles in the aerosol was generated by exposure to
shorter laser wavelengths. Since the incomplete vaporization of large particles in ICP is a
primary source of elemental fractionation 70
,the absence or reduced presence of particles larger
than 200 nm when using 193 nm laser is reflected in more stable transient signals and smaller
variations in intensity ratios, indicating reduced time-dependent elemental fractionation 4
.
Many studies investigating the impact of laser wavelength have used NIST 61X series glass
reference materials as samples, where the material’s transparency is a significant factor. Even
within the UV region, reducing the wavelength is crucial for the ICP response and time-
dependent fractionation. This is evident from Figure 9 which compares the fractionationindex
(see definitionin Chapter 2.3) for 43 elements with respect to 42
Ca during the ablationof NIST
610 at wavelengths of 266 nm, 213 nm, and 193 nm. The FI was calculated from the intensity
ratios of the second 30 s and first 30 s of one-minute ablation with a repetition of 4 Hz. A
fractionation index of one indicates no time-dependent fractionation.
Fig. 9. Fractionation index for 43 elements with respect to 42Ca for the ablation of NIST 610. Error bars
represent the standard deviation (1σ) from 5 measurements for each wavelength 45.
The applicabilityof these findings to other types of samples,beyond glass reference materials,
has been verified, for example, with metallic, Fe-based materials 4
. Using a 193 nm excimer
laser has been shown to significantly reduce the formation of particles larger than 150 nm,
which are commonly present up to 350 nm when using a 266 nm Nd:YAG laser (as measured
by OPS in the 65 nm - 1 µm range). Figure 10 illustrates the PSD for both types of lasers.
Fig. 10. Normalised particle size distribution of the generated aerosol measured during LA of Fe-based
samples: a) 193 nm UV-ns-(ArF*); b) 266 nm UV-ns-(Nd:YAG) 4
.
3.2 Laser pulse duration
The pulse duration is a parameter that significantlyaffects the ablation process. However, it is
an immutable characteristic,determinedbythe designof the laser system.Hence,this parameter
is essentiallypredeterminedat the time of selectingor purchasinga laser setupfor LA-ICP-MS.
Lasers are generally classified into three groups based on the pulse duration: nanosecond,
picosecond, and femtosecond. Research consistentlyindicates that reducing the pulse duration
positivelyaffects the accuracyandprecisionof analytical results 71
.This is because shorter laser
pulses provide less time for thermal effects to induce fractionation.
In femtosecondlaser ablation, the energy transfer occurs in two stages. The first stage happens
in the initial few femtoseconds of the laser pulse, during which the sample's surface layer
absorbs photons and undergoes photon ionizationprocesses,excitingthe electrons. The second
stage lasts a few hundred femtoseconds to picoseconds and involves the transfer of absorbed
energy to the lattice throughelectron-phononcoupling. This leads to thermal evaporationof the
sample, known as 'strong ablation', or to the direct removal of heavy atoms and ions, termed
'soft ablation'.Both ablationprocesses can occur simultaneously,with the contributionof each
depending on the laser intensity and the ablation thresholds of the sample 72
.
Longer laser pulses, such as those in the nanosecond and picosecond ranges, increase the
proportionof thermal effects, causingnon-stoichiometricablation(preferentialvaporizationof
volatile components) 10, 37, 71, 73
. The heat transfer during these longer pulses results in material
melting. The mechanical interaction between the molten liquid and plasma leads to the
formation of large particles in the aerosol (up to units of micrometres), a process known as
hydrodynamic sputtering. The extent of the hydrodynamic sputtering depends on the melt
thickness creatingthe upper layer of the ablationcrater surface. Typically,greaterheat diffusion
and lower fluences lead to increasedmelt thickness, thereby prolonging the solidificationtime
and consequently enhancing fractionated evaporation and hydrodynamic sputtering. The
thermal diffusivityof materials,suchas metal andglass,canresult ina melt layer approximately
an order of magnitude thicker inmetals under fluences below 10 J cm−2 74
. The amount and size
of the droplets formed depend on the thickness of the melt layer, and models of hydrodynamic
sputtering have been developed for various ablation conditions 75
.
An explanation for the reduction in fractionation when using a shorter pulse can be given by
comparing PSD and particle composition. The direct removal of material in a gas phase leads
to a gas-to-particle conversion, resulting in primary nanoparticles within the nucleation size
range (< 30 nm) and their agglomerates,which can reach sizes of hundreds of nanometres 7, 8
.
In contrast,particles createdbythermal effects and thermodynamic sputtering attain sizes of up
to several micrometres and are typically characterised by spherical symmetry 4, 10, 37
.
Alternative methods for measuringablatedparticles have shown that the chemical composition
of these particles varies depending on their size and, consequently, their origin 10, 76
. Primary
nanoparticles and their agglomerates are often enriched with more volatile components,
whereas refractory components tend to accumulate in larger particles. This trend was also
confirmed in cobalt-cemented tungsten carbide, a system comprising both high- and lowvolatile
components. Large particles showed enrichment with tungsten, a less volatile element,
while clusters of smaller particles exhibitedobvious depletionof W and enrichment of Co. The
condensation of Co on larger spherical particles is also distinctly visible 10
.
This situation is illustrated in Figure 11, where the 5x4 mm filter area is covered by network
of nanoparticles, their clusters, and one large spherical particle. Figure 11a, captured using
Back-scattered Electrons (BSE), shows the overall distribution, while Figures 11b-11d,
obtained via Energy Dispersive X-ray Spectrometry (EDS), depict the elemental distribution
within the particles. The EDS mapping highlights the evident accumulation of tungsten in
spherical particles and the uniform distribution of cobalt in agglomerates. The original
composition of the sample was (% wt): C 6.13, Co 3.33, Ta 1.03, Nb 0.42, and W 89.09.
Fig. 11. The elemental distribution maps of particles collected from sample no. 1457HF3, measured on
a 5 x 4 mm filter area; a) BSE picture of the particles on the filter, b) tungsten and c) cobalt detected in
this area, and d) common map of major elements (W, Co, C, O) 10
.
The employment of femtosecond(fs) laser pulses (fs-LA) enables the eliminationor significant
reductionof micrometric-scale particle formation,a common occurrence with nanosecond (ns)
pulses (ns-LA). The interaction mechanisms of fs-LA with a target are associated with a
reductionin thermal effects, leadingto decreased material melting.For instance,during UV-fsLA
of Fe-based sample,only nano-sizedagglomerates rangingfrom 50–250 nm were observed
(Figure 12b), while UV-ns-LA generatedan aerosol showing a bimodal distributioncomposed
of micro-sized molten spherical particles and nano-sized agglomerates (Figure 12a) 4
.
Fig. 12. SEM images of the collected aerosol particles obtained for an Fe metal sample using: a) UV-ns(Nd:YAG)LA;
b) UV-fs-(Ti-sapphire)LA. These images show the different kinds of transported particles
observed for each laser system but are not representative of the total transported mass 4.
Shortening the pulse duration can lead to a significant increase inthe accuracy and precisionof
the analytical method. A case in point is the analysis of Fe-based samples using lasers with
almost identical wavelengths but differing pulse durations (Nd:YAG 266 nm, 4 ns and Tisapphire
265 nm, 150 fs). Matrix-matched (within metallic samples) and non-matrix matched
calibrations were employed for analysing Fe-based samples,using a silicate glass (SRM NIST
610) as non-matrix matched calibration sample (glass-metals). Notably, improved analytical
results in terms of precision and accuracy were achieved using femtosecond laser ablation,
particularly when using similar matrices for calibration. Furthermore, non-matrix matched
calibrationemployedfor quantificationprovidedmore accurateresults (5–15% RSD) compared
to UV-ns-LA-ICP-MS (5–30% RSD) 4
. For a comprehensive summaryof these results,refer to
Table 2.
Table 2 Elemental content values, relative standard deviations (n=6) and accuracy values (bias from
reference content) found for SRM JK27A using matrix and non-matrix matched calibration. a) UV-ns
(Nd:YAG)-LA-ICP-MS; b) UV-fs (Ti-sapphire)-LA-ICP-MS 4.
3.3 Laser fluence
Fluence, defined as laser energy per unit area, significantly influences the nature of laser
ablation sampling. It affects not only the amount of mass ablated but also the degree of
fractionation. Unlike pulse duration, where shorter times are generally recommended, there is
no universal guideline for settingfluence,and it must be carefullytailoredfor each sample. The
appropriate fluence value depends on the combination of the sample properties (especially its
absorption at the applied laser wavelength, thermal conductivity, and melting point) and laser
parameters, such as wavelength, pulse duration, or spot size. Generally, samples that have
higher optical transparency for the wavelength of the applied laser require higher fluence.
However, highfluences for samples withhigh thermal conductivityandlowmeltingpoints may
induce melting and splashing of the sample that might result in deviations from the expected
element ratio 77
. This is especiallytrue when applying repeated pulses to the same spot, as the
overall process also depends on the number of pulses used 14
.
A different scenario arises when scanning the sample surface along a line. Here, by adjusting
the crater size, scanning speed, and repetition rate, the degree of overlap of individual laser
shots is selected. Consequently, laser ablation partly occurs on the previously ablated surface
and partly on the untouched surface. It is possible to set a scanning speed where the craters do
not overlap, meaning the molten surface of the sample does not affect subsequent pulses.
Such a model was applied to the study 6
which demonstrates that the final representation of
individual elements in the Al alloy sample varies based on the laser fluence used. Using higher
fluences of ns laser reduces preferential vaporizationof volatile components. The change in the
response of measured analytes persists even after the application of several pre-shots. In the
case of metallic materials where extreme melting occurs, the composition may permanently
change due to surface re-melting,especiallyat lower fluences. The experiment was performed
Fig. 13. a) The total elemental representation (expressed as a percentage of sum of signal intensities)
for BAM 311 sample with different surface roughness: 1 polished (14.0), 2 #2000 (73.0), 3 #1200
(190.0), 4 #500 (335.0), 5 #220 (875.7) and 6 #80 (2717.3); b) The image of a polished BAM 311 surface:
EDX map of elemental distribution. Cu (red) and Mg (turquoise) form dendrites. Bi and Pb (green) are
captured together in small inclusions within dendrites. Al (blue) is mainly contained in the space
between them; c) SEM image of the polished BAM 311 sample surface ablated by 1 J cm-2
spot by spot
of 110 μm diameter 6
.
on the BAM 311 sample (composition in m/m %: Al 92 %, Cu 4.7 %, Pb 0.05 %, Bi 0.05 %,
other elements ~ 3 %) prepared with different surface roughness to also demonstrate the effect
of surface topography on laser ablation. The influence of surface properties on laser-matter
interactionis a separate phenomenon,covered in Chapter 3.6. To illustrate the effect of fluence,
compare the compositionof the ICP-MS response of individual analytes within columns 1 – 6
in Figure 13a, which represent the same sample with varying surface topography. Focusing on
column 1, corresponding to the polished sample (preparation of surfaces by the usual
procedure), a substantial change in the composition of the registered signal with increasing
fluence is evident. Lower fluences lead to higher representation of volatile components
(especially Pb and Bi), which are present in the sample in minor quantities compared to
aluminium, the predominant element in the alloy. This can be explainedby two factors.Firstly,
the different physical properties of elements: Pb and Bi are extremely volatile with melting
points of 207ºC for Pb and 271ºC for Bi. Secondly, their distribution within the matrix differs
from other elements. Figure 13b shows that the alloy exhibits a dendritic structure that was
created during the unidirectional solidification process. Due to different melting points and
solidification ratios of elements, the dendrites are enriched with Cu, Bi and Pb. Although
globally homogeneous, this dendritic structure introduces micro-heterogeneity to the sample,
creating regions with varying melting and boiling points or optical properties, potentially
causing fractionation. This effect is most pronounced at low fluences, where preferential
ablation occurs primarily in the areas of dendrites, as illustrated in Figure 13c.
Irrespective of the sample properties, fluence remains one of the most critical variable
parameters in laser ablation. Optimizing fluence is essential to achieve precise (minimal
fractionation effect) and accurate (sufficient mass ablated) analytical results. The appropriate
fluence value is primarilyrelatedto the sample matrix,laser pulse duration, and the number of
applied pulses.
3.4 Ablation mode and spot size
In LA-ICP-MS, two ablation modes are commonly used. The first is the spot ablation mode,
where a specific number of laser pulses are repeatedlydirectedat a single point. The number of
pulses can varybased on the nature of the analysis,rangingfrom a single pulse (known as single
pulse ablation) to hundreds or even thousands of pulses. These pulses generate the aerosol
necessary for trace analysis from that specific area or to create a depth profile. The second
frequentlyused mode is the scanning mode, where the sample is moved at a predefinedspeed,
typicallylinearly.The combination of the set laser repetition rate and spot size with this speed
determines the degree of overlap between individual pulses.
It has been observed that the settings of the ablation mode can significantly influence the
formation of aerosols and, consequently, the resulting analytical signal. For instance, in spot
ablation, the spot size impacts not only the quantity of generated particles but also their size
distribution 7
.Whenmonitoringparticles generatedbyspot ablationwith a ns laser on the SRM
NIST 610 sample, a shift in PSD peak, correspondingtothe nucleationof nanoparticles (around
10-20 nm), was noted towards larger sizes with increasingapplied spot diameter (Figure 14a).
This shift is attributed to the greater amount of material evaporated. The second peak in the
PSD, indicative mostly of the coagulation/agglomerationof primarynanoparticles (at 190 nm),
remains constant inpositionirrespective of the spot size,although the concentrationof particles
changes.As anticipated,the particle concentrationof all sizes escalates with an enlarging spot.
Fig. 14. a) EEPS particle size distribution graphs (average of 80 s spot ablation) for different spot sizes,
the error bars indicate standard deviation of 5 measurements; b) Distribution map for temporal
behaviour of particle number concentration in individual size channels for spot size of 85 μm. The
particle concentration scale is shown to the right of the graph dN/dlog(dp) (particles cm−3
) 7
.
In Figure 14b, temporal changes in the PSD during spot ablation with an 85 µm spot size are
depicted. There is a noticeable increase in the production of particles with diameter (Dm) of
approximately 190 nm within the first 10 seconds of spot laser ablation. The production of
primary nanoparticles begins roughly 20 seconds after the start of ablation, corresponding to
200 pulses applied. Furthermore,the number concentrationof particles with Dm < 50 nm rises
as the crater becomes deeper. Such behaviour at the start of surface layer ablation is consistent
with the theory that nanoparticles are scavenged by larger particles originatingfrom the intact
material surface.As the crater deepens, the production of larger particles decreases 78
, leading
to a relative increase in the concentration of smaller nanoparticles. Overall, the dynamics of
spot ablation change continuously during the ablation process.
The temporal record of PSD for spot ablation reveals differences in laser interaction with the
original sample surface compared to a layer of material alteredby preceding laser pulses. This
phenomenon is also observable for the scanning mode of laser ablation, specificallyregarding
the degree of laser spot overlap, i.e., the ratio of original to already ablated material within a
single pulse.At the same laser repetitionrate,this means that slower scanningspeeds will more
closelyresemble spot ablation.This was confirmed using SRM NIST 610 for spot ablationand
various scanning speeds, all employing an 85 µm spot size and a 10 Hz repetitionrate (Figure
15a) 7
. Slower scanning speeds led to an increased production of primary nanoparticles and a
closer resemblance tospot ablation,where the sample remains static. The peakfor agglomerated
particles consistentlyremains at 190 nm across different speeds, mirroringthe findings in spot
ablation. Figure 15b illustrates that the ablation process in line scan mode is more stable
compared to spot ablation mode. In the case of a scan speed of 40 μm s-1
, the scan ablation
stabilizes after the initial 10 seconds.
Fig. 15. a)EEPS particle size distribution graphs (average of 80 s spot ablation) for different scan speeds,
the error bars indicate standard deviation of 5 measurements; b) Distribution map for temporal
behaviour of particle number concentration in individual size channels for scan speed of 40 μm s−1. The
particle concentration scale is shown to the right of each graph dN/dlog(dp) (particles cm−3) 7.
When comparing spot and line scanning ablation modes using the APS instrument, capable of
measuring PSD in the range of 540 nm - 17 µm, it was found that line scan ablation produces
up to 10 times more particles in this size range, as evidenced in Figure 16 for 85 µm spot
ablationvs. scanning ablationat a speed of 40 µm s-1
. Such an increase in large particles causes
a considerable rise in the overall volume of the sampled material introduced into the ICP,
thereby enhancing the response of measured analytes in line scan ablation mode 7
.
Differences in aerosol PSD between spot and line scan ablation have also been the subject of
another study 8
, which further explores the comparison of particle formation relative to the
sample matrix. This aspect will be discussed in greater detail in the subsequent chapter.
Fig. 16. Particle size distribution by Aerodynamic Particle Sizer for spot ablation mode (85 μm) and line
scan (40 μm s−1
) of SRM NIST 610; the error bars indicate standard deviation of 5 measurements 7
.
3.5 Sample matrix
The laser-matter interaction is significantly influenced by the sample's physical and chemical
properties.These include, for example, the absorption coefficient,which determines the extent
of laser energy absorption at a specific wavelength, the thermal conductivity of the sample
affecting heat transfer, and the degree of plasma shielding, which refers to the attenuation of
incoming laser radiation 79
. Conversely, laser irradiation can substantially alter the sample's
optical and thermo-physical properties,leadingto changes in surface reflectivity,electricaland
thermal conductivity, surface tension, and latent heat of vaporization.
Depending on the sample matrix,there is a specific interactionbetween laser radiationand the
formation of aerosol particles, occurring predominantly through two fundamental processes.
Firstly, the aerosol is formed via a gas-to-particle conversion process, typically resulting in
smaller particle sizes. Studies investigatingparticle formationhave revealed that nanoparticles
produced by vapor nucleationare generallysmaller than100 nm (subject to variations basedon
laser and sample parameters) before cluster agglomerationcommences 80
.Detailedobservation
of nanoparticle formation is challenging due to the irregular shapes and undefined density of
the clusters they form.
Secondly, the aerosol is formed through heat transfer processes that cause material melting,
followed by liquid-plasma interaction, leading to the creation of larger particles in the aerosol
through hydrodynamic sputtering. The extent of hydrodynamic sputtering is dependent on the
thickness of the molten layer forming the upper part of the ablation crater surface. Increased
heat diffusion and lower fluences typically result in a thicker melt layer, extending the
solidificationtime andenhancingfractionatedevaporationandhydrodynamic sputtering 74
.The
thickness of this melt layer is a determining factor for the quantity and size of the generated
droplets. For example, the thermal diffusivity difference in materials such as metals and glass
can lead to a melt layer about an order of magnitude thicker in metals under fluences below
10 J cm−2 74
. This principle is influenced not only by the sample matrix but also by the
parameters of the laser radiation, particularly wavelength and pulse duration.
Some observations have been able to approximately delineate particle formation during the
condensation process using ns lasers. Commonly, two size distribution modes are observed 75,
81
. The size of particles inthe primarymode is mainly influencedby the ablationmode 7, 8
, with
smaller sizes noted for line ablation,and is largely independent of the type of ablated material.
This is attributed to a similar mechanism of primary particle formation across all materials,
involving evaporation followed by the condensation of vapours, under conditions set by the
laser ablation setup (includinglaser settings,carrier gas, etc.). In contrast,the size of particles
in the accumulation mode is material-dependent, as illustrated in Figure 17 when comparing
metal andglass. Notably,for SRM NIST 610, the accumulationmode of the PSD shifts tolarger
sizes (200 and 220 nm for spot and line ablation, respectively) compared to steel F4 material
(120 and 160 nm for spot and line ablation, respectively) for both ablation modes.
Fig. 17. Average PSD for laser ablation of different materials (glass NIST610 and steel F4) and different
ablation modes (measured by EEPS). Ablation conditions: ns laser (193 nm), 110 µm spot size, 8 J cm-2
,
10 Hz, scan speed of 20 µm s-1 8
.
Furthermore,the overall size distributionexhibits lower concentrations for the ablationof steel
material. The greater tendency of SRM NIST 610 for clustering compared to steel F4 was
confirmedthrough particle observation using TEM, as illustrated in Figure 18. NIST 610 was
observed to predominantly form clusters consisting of a single type of particle, whereas F4
produced two distinct particle types. The large spherical particles, characteristic of
hydrodynamic sputtering of the liquid layer, can reach sizes of up to several micrometres.
Fig. 18. TEM image of particles produced by spot ns laser ablation (193 nm, 110 µm spot size, 8 J cm-2,
10 Hz) a) SRM NIST 610, b) steel F4 8.
Although the quantity of particles generated by hydrodynamic sputtering may seem
insignificant compared to the total number of particles, their considerable size - up to several
micrometres - means that they constitute a significant portionof the total aerosol volume. Both
the quantityand size of these particles are influenced not only by the laser ablationparameters
but also significantly by the material's matrix. This is particularly evident when comparing
different materials under identical ablation conditions. Figure 19 shows PSD in the size range
of 0.25–2.5 μm, encompassing the entire range for particles produced by hydrodynamic
sputtering 9
. Three materials with different matrices are presented: metal (steel),metal-ceramic
(Co-cemented tungsten carbide hardmetal),and non-metal (glass) sample. In the steel sample,
the highest number concentration of particles is observed, along with the presence of particles
reaching the largest sizes. In contrast, the glass sample exhibits the smallest particles in the
lowest concentrations. This variation is linked to the thermal conductivity of the samples; a
higher thermal conductivity leads to the formation of a thicker molten material layer on the
surface, serving as a source for material sputtering.
The extent of thermal effects on
a sample can be evaluated by
examining the structure and
dimensions of the ablation
crater. Significant melting of
the sample becomes apparent
through the characteristics of
the crater's bottom, its rim, and
the particles deposited around
it. These features can be
observed using a confocal
microscope or profilometer,or
through electron microscope
imagery as shown in Figure 5.
Figure 20 presents a
comparative analysis of two
ablation craters created under identical conditions but on different material types. The SRM
NIST610 glass produces a regular crater, devoid of signs of a molten bottom or an expanded
rim, and the resultant particles resemble agglomerates of primary nanoparticles (Figure 20a,
c). Conversely, a metal sample displays pronounced melting, especially evident at the crater's
rim and bottom, as well as in the abundance of deposited particles (Figure 20b, d). These
particles are indicative of thermodynamic sputtering of the melt. Additionally, they serve as
'traps' for capturing primary particles, reducing the efficiency of particle transport to the ICP.
The process of matrix unification effectively reduces the disparities in ablation mechanisms
amongdifferent samples.This effect was clearlydemonstratedina studyinvolvingCo-tungsten
carbide precursor powder samples 11
.For laser ablation,these samples were preparedas pressed
pellets,either without a binder or using silver as botha binder and a matrixunifier.The analysis
focusingon particle formationandablationcratercharacteristics highlightedthe significant role
played by the matrix unifier. Notably, it led to a reduction in variations in the total particle
concentrationamong the samples, with the relative standard deviation (RSD) decreasing from
46% to 19%, as shown in Figure 21. Similarly, the disparities in the volumes of the ablation
craters were also minimised, with the RSD dropping from 36% to 16% 11
.
Fig. 19. Particle size distribution graph measured by optical
aerosol spectrometer Welas® for large spherical particles (Cocemented
tungsten carbide sample no. 3648 K, steel no. 54666,
and glass no. U12) 9.
Fig. 20. SEM of the ablation craters after 100 pulses a) NIST 610, b) steel F4 and detail of deposited
particles c) NIST 610, d) steel F4 8
.
Fig. 21. Total concentration of particles (10 nm–17 µm) formed during the laser ablation of non-matrixunified
(without binder) and matrix-unified (with Ag binder) Co-tungsten carbide samples. The errorbars
signify the standard deviation of three parallel measurements of each sample 11
.
3.6 Sample surface
While the intrinsic chemical and physical properties of a sample are typically unalterable, its
surface - which directlyinteracts with laser radiation - can often be modifiedprior to analysis.
There are exceptions,such as porous samples,biological specimens,cultural heritage artefacts,
or powdered materials.A standard approach to sample preparation involves surface polishing
using diamond paste to achieve a smooth finish. Research has demonstrated that intentional
surface treatments, aimed at modifying optical or thermal characteristics, can enhance the
analytical performance of LA-based techniques.
For example, roughening the sample surface can amplify the LA-ICP-MS signal. This
enhancement is attributedto decreased material reflectivityandincreased energy transfer from
the laser pulse through the material's sharp edges 6
. In the referenced study, certified glass
standard reference material (SRM) NIST 610 and aluminium alloy standard BAM 311 (BAM,
Germany) were utilised as samples. Different levels of surface roughness were achieved
through wet grinding or polishing with various silicon carbide papers (ranging from #80 to
#2000) or diamond pastes of 3 μm and 1 μm. The resultingsurface roughness values for these
samples are listed in Table 3.
Table 3 Surface roughness measured by an optical 3D microscope for samples with different grinding
set up 6
.
The LA-ICP-MS response for measured isotopes was assessed across different fluences (1, 3,
5, 10, and 13 J cm-2
). Each measurement was carried out as a "spot by spot" (no pulse overlap)
line scan of 5 mm length and 10 repetitions. The average counts per second (cps) for each
isotope were calculatedalongwiththe standarddeviation(SD). Subsequently,these values were
compared across isotopes and varying fluences. By comparing the cps of samples with specific
roughness against those of polished samples,changes in signal response were estimated. As the
ratio between cps of samples with specific surface roughness and the cps of polished samples
exceeded one in most cases, it is referred to as 'enhancement'. The correlation between
enhancement and surface roughness is depicted in Figure 22.
Fig. 22. The ratio between cps of samples with specific surface roughness and the cps of polished
samples for selected isotopes as a function of surface roughness a) BAM 311; b) NIST 610 6
.
a
b
Beyond the effect of fluence, surface roughness contributed significantly to signal
enhancement. Higher analytical ICP-MS signals for measured isotopes suggest an increase in
ion production from the aerosol.This aerosol formed by the interactionof the laser pulses with
the sample, caneither be larger in volume or have a different structural composition. Toquantify
the total mass generated by LA, a DustTrack DrX monitor was used. It measured the aerosol
mass produced from ablating both a polished sample and a sample with #220 roughness
(exhibiting the highest enhancement) across various fluences (1, 3, 5, 10, and 13 J cm-2
) for
both material types. The analysis revealed that the Al alloy sample with #220 roughness
generated an increase in aerosol mass exceeding an order of magnitude, achieving up to fifty
times the mass compared to the polished sample. In contrast, NIST 610 demonstrated an
increase in aerosol production by less than an order of magnitude (as shown in Table 4). These
results are consistent with the signal enhancement observed for both materials, validating that
samples with higher surface roughness produce a larger mass of aerosol particles.
Table 4 Ablated mass [mg m-3
] during laser ablation with various fluencies (1, 3, 5, 10 and 13 J cm-2
)
and reflectivity of polished sample and sample #220 (with the highest enhancement in case of alloy) 6
.
Another approach to enhance analyte signals involves applying metal nanoparticles to the
sample surface, a technique referred to as NE-LA-ICP-MS (Nanoparticle-Enhanced Laser
Ablation InductivelyCoupled Plasma Mass Spectrometry) 5
. In experiments using Aluminium
alloyAW 2030 as the model sample (with a compositionby weight %: 92% Al, 3.9% Cu, 1.2%
Pb, 0.8% Mg, 0.6% Mn, and 0.1% Fe), the application of metal nanoparticles in the form of
dried droplets led to a significant amplification of the analyte signal, as shown in Figure 23.
This enhancement exceeded two orders of magnitude while reducing the detectionlimits by an
order of magnitude. The extent of signal amplification was observed to vary with the applied
fluence. Table 5 presents a comparative analysis of detection limits for various fluences,
contrasting the clean surface of aluminium alloy AW 2030 with a surface coated with 40 nm
AgNPs.
The observed improvements on
metallic targets might suggest a role
for surface plasmon resonance and
an intensificationof the electric field
between the nanoparticles (NPs) and
the surface 82
. However, the ICP-MS
signal increases monotonously with
the surface NP concentration, which
is atypical for surface plasmon
resonance, where emission usually
decreases beyond a critical NP
concentration.Anexaminationof the
ablation craters revealed that the
presence of nanoparticles does not
necessarily lead to increased
material removal but does alter the
crater's structure. Figure 24a
illustrates the contrast between a
crater formedby a single laser pulse
(213 nm, 100 μm diameter, with
fluence of 4.5 J cm−2
) at the boundary of a clean sample surface and an area with drieddroplets
containing 40 nm AgNPs. The presence of NPs appears to result in smoother ablation craters
with less material splashing. This observation led to the hypothesis of potential variations in
aerosol structure, later confirmed by a study showing different particle size distributions
between a polished sample surface and a surface coated with gold nanoparticles of various
sizes 12
. When employingthe NE-LA-ICP-MS method, a larger proportionof smaller particles
(<30 nm) was produced, at the expense of particles around 100 nm and larger (Figure 24b).
This phenomenoncan be attributedtotwo mainfactors: firstly,different clusteringmechanisms
employed by the two methods; and secondly, reduced thermal effects during NE-LA, leading
to fewer large spherical particles typicallyformedby the solidificationof sprayed sample melt,
a process known as hydrodynamic sputtering. The experimental findings conclusively
demonstrate that the NE-LA-ICP-MS methodproduces a higher proportion of smaller particles
(<30 nm) in comparison to conventional LA-ICP-MS, approaching an ideal monodisperse
aerosol that can be efficiently vaporized in the ICP. This discovery provides a foundation for
future research aimedat developing strategies to reduce the undesirable effects of fractionation
in LA.
Fig. 23. a) Photograph of the ablated area with a dried
droplet of 40 nm AgNPs and craters on the aluminium
alloy (AW 2030) sample for a fluence of 4.5 J cm−2; and
ICP-MS intensity maps with xy cross-sections for
analyte b) Mg; c) Ag; and d) Pb 5
.
Table 5 LODs (μg g−1
) for different fluences (J cm−2
) without and with 40 nm AgNPs on the sample
surface (comparing LA-ICP-MS and NE-LA-ICP-MS methods) 5
Fig. 24. a) Crater image by SEM-BSE for a fluence of 4.5 J cm−2
on the interface of the droplet with 40
nm AgNPs (right) and the surface without NPs (left) 5
; b) Particle size distribution measured by EEPS
(5.6–560 nm, arbitrary concentration units) of LA and NE-LA aerosol using different sizes of
nanoparticles for fluences 1 J cm-2 12
.
4 Conclusion and outlook
This habilitation thesis comprehensively deals with the sampling of solid materials by laser
ablationfor mass spectrometrywithinductivelycoupledplasma (LA-ICP-MS) emphasizingthe
prevalent application of the most used nanosecond lasers. It seeks to contribute to the
elucidationof the complex dynamics between the laser pulse and the sample. It indicates how
numerous parameters, such as laser wavelength, pulse duration, fluence, ablation mode, scan
speed, and laser beam size, as well as physical and chemical properties - especially the matrix
and surface - critically affect this interaction.
The researchincluded in the habilitation thesis shows that the use of shorter laser wavelengths,
specifically the reductionfrom 266nm to 193 nm, significantlylimits the formationof particles
larger than 150 nm during the ablationof metal samples.This finding underscores the potential
for improved precision in particle size control during aerosol generation. The study further
shows that the duration of the laser pulses significantly affects the thermal dynamics during
ablation. Longer pulses in the nanosecond and picosecond range enhance non-stoichiometric
ablationdue to preferential evaporationof volatile components,resultinginsignificant material
melting.This moltenmaterial mechanicallyinteracts withthe plasma,leadingtothe production
of larger particles by hydrodynamic sputtering and thereby affecting the particle size
distribution and composition of the aerosol. The use of femtosecond laser pulses has been
shown to be helpful in mitigating microparticle formation - a prevalent problem with longer
nanosecondpulses - by reducingthermal effects andminimizingmaterial melting.This advance
in pulsed laser ablation not only refines aerosol particle sizes, but also increases the analytical
accuracy and precision of the LA-ICP-MS method.
In addition, adjustments in the fluence and ablation mode are shown to play a pivotal role.
Higher fluences with nanosecond lasers reduce preferential evaporation of volatiles on metal
samples, independent of surface topography. The findings also confirm that the setting of the
ablation mode, especiallythe spot size in spot ablation or the scan speed in scanning ablation,
significantlyaffects the particle size distributionand thus directly affects the analytical signal.
This work further confirmedthat matrixandsample surface modificationsare keytooptimizing
the laser-matter interaction. Surface treatments such as roughening, or deposition of metal
nanoparticles can significantlyaffect the amount and size of produced particles due to changes
in the optical and thermal properties of the surface. These modifications not only enhance the
analytical signal, but also substantially reduce the detection limits.
The work underlines the basic factors influencingthe course of laser-matter interactionandthe
formationof sample aerosol usingmethods suchas diagnostics of ablationcraters,measurement
of aerosol particle size and concentration, and analysis of analytical signals. Other parameters
such as carrier gas type and flow rate, ablation cell geometry and laser repetition rate are
certainly very important, and all these factors require thorough optimization for accurate and
precise application of the LA-ICP-MS method.
In conclusion, the LA-ICP-MS technique is in a state of constant development. The move to
shorter-wavelength,shorter-pulse lasers is designedto alleviate fractionationissues,alongwith
the development of new calibrationstandards and advanced results processingthat account for
factors such as fractionation, matrixeffects,and sample inhomogeneities. These advancements
propel the method towards faster analyses, enhanced spatial resolution, reduced detection
limits,and expanded applicability. The methodis increasinglyused not only for the analysis of
trace elements,but also for the precise determinationof the isotopic ratioand the identification
and quantification of proteins after their labelling. This thesis significantly contributes to a
deeper understandingof laser-matter interactions, pivotal for the continuous improvement and
expansion of LA-ICP-MS applications across different scientific disciplines.
5 References
1. V. Wertich, M. Kubes, J. Leichmann, M. Holá, J. Haifler, J. Mozola, P. Hrselová, M. Jaros. “Trace
element signatures of uraninite controlled by fluid-rock interactions: A case study from the Eastern
Moldanubicum (Bohemian Massif)”. Journal of Geochemical Exploration. 2022. 243: 107111.
doi:10.1016/j.gexplo.2022.107111.
2. M. Hola, J. Kalvoda, H. Novakova, R. Skoda, V. Kanicky. “Possibilities of LA-ICP-MS technique for the
spatial elemental analysis of the recent fish scales: Line scan vs. depth profiling”. Applied Surface
Science. 2011. 257(6): 1932-1940. doi:10.1016/j.apsusc.2010.09.029.
3. M. Hola, K. Novotny, J. Dobes, I. Krempl, V. Wertich, J. Mozola, M. Kubes, V. Faltusova, J. Leichmann,
V. Kanicky. “Dual imaging of uranium ore by Laser Ablation Inductively Coupled Plasma Mass
Spectrometry and Laser Induced Breakdown Spectroscopy”. Spectrochimica Acta Part B-Atomic
Spectroscopy. 2021. 186: 106312. doi:10.1016/j.sab.2021.106312.
4. V. Mozna, J. Pisonero, M. Hola, V. Kanicky, D. Guenther. “Quantitative analysis of Fe-based samples
using ultraviolet nanosecond and femtosecond laser ablation-ICP-MS”. Journal of Analytical Atomic
Spectrometry. 2006. 21(11): 1194-1201. doi:10.1039/b606988f.
5. M. Hola, Z. Salajkova, A. Hrdlicka, P. Porizka, K. Novotny, L. Celko, P. Sperka, D. Prochazka, J. Novotny,
P. Modlitbova, V. Kanicky, J. Kaiser. “Feasibility of Nanoparticle-Enhanced Laser Ablation Inductively
Coupled Plasma Mass Spectrometry”. Analytical Chemistry. 2018. 90(20): 11820-11826.
doi:10.1021/acs.analchem.8b01197.
6. Z. Salajkova, M. Hola, D. Prochazka, J. Ondracek, D. Pavlinak, L. Celko, F. Gregar, P. Sperka, P. Porizka,
V. Kanicky, A. Giacomo, J. Kaiser. “Influence of sample surface topography on laser ablation process”.
Talanta. 2021. 222: 121512. doi:10.1016/j.talanta.2020.121512.
7. H. Novakova, M. Hola, M. Vojtisek-Lom, J. Ondracek, V. Kanicky. “Online monitoring of nanoparticles
formed during nanosecond laser ablation”. Spectrochimica Acta Part B-Atomic Spectroscopy. 2016.
125: 52-60. doi:10.1016/j.sab.2016.09.017.
8. M. Hola, J. Ondracek, H. Novakova, M. Vojtisek-Lom, R. Hadravova, V. Kanicky. “The influence of
material properties on highly time resolved particle formation for nanosecond laser ablation”.
Spectrochimica Acta Part B-Atomic Spectroscopy. 2018. 148: 193-204. doi:10.1016/j.sab.2018.07.001.
9. M. Hola, V. Konecna, P. Mikuska, J. Kaiser, V. Kanicky. “Influence of physical properties and chemical
composition of sample on formation of aerosol particles generated by nanosecond laser ablation at
213 nm”. Spectrochimica Acta Part B-Atomic Spectroscopy. 2010. 65(1): 51-60.
doi:10.1016/j.sab.2009.11.003.
10. M. Hola, V. Konecna, P. Mikuska, J. Kaiser, K. Palenikova, S. Prusa, R. Hanzlikova, V. Kanicky. “Study
of aerosols generated by 213 nm laser ablation of cobalt-cemented hard metals”. Journal of Analytical
Atomic Spectrometry. 2008. 23(10): 1341-1349. doi:10.1039/b802906g.
11. M. Hola, P. Mikuska, R. Hanzlikova, J. Kaiser, V. Kanicky. “Tungsten carbide precursors as an example
for influence of a binder on the particle formation in the nanosecond laser ablation of powdered
materials”. Talanta. 2010. 80(5): 1862-1867. doi:10.1016/j.talanta.2009.10.035.
12. M. Hola, Z. Salajkova, A. Hrdlicka, J. Ondracek, K. Novotny, D. Pavlinak, M. Vojtisek-Lom, L. Celko, P.
Porizka, V. Kanicky, D. Prochazka, J. Novotny, J. Kaiser. “The effect of nanoparticle presence on aerosol
formation during nanoparticle-enhanced laser ablation inductively coupled plasma mass
spectrometry”. Journal of Analytical Atomic Spectrometry. 2020. 35(12): 2893-2900.
doi:10.1039/d0ja00324g.
13. R.E. Russo, X.L. Mao, H.C. Liu, J. Gonzalez, S.S. Mao. “Laser ablation in analytical chemistry - a
review”. Talanta. 2002. 57(3): 425-451. doi:10.1016/s0039-9140(02)00053-x.
14. C.C. Garcia, H. Lindner, K. Niemax. “Laser ablation inductively coupled plasma mass spectrometrycurrent
shortcomings, practical suggestions for improving performance, and experiments to guide
future development”. Journal of Analytical Atomic Spectrometry. 2009. 24(1): 14-26.
doi:10.1039/b813124b.
15. E. Vanícková, M. Holá, K. Rapouch, D. Pavlinák, R. Kopecká, V. Kanicky. “LA-ICP-MS analysis of metal
layers on samples of cultural heritage”. Chemical Papers. 2019. 73(12): 2923-2936.
doi:10.1007/s11696-019-00745-6.
16. J. Pisonero, J. Koch, M. Wälle, W. Hartung, N.D. Spencer, D. Günther. “Capabilities of femtosecond
laser ablation inductively coupled plasma mass spectrometry for depth profiling of thin metal coatings”.
Analytical Chemistry. 2007. 79(6): 2325-2333. doi:10.1021/ac062027s.
17. M.L.Warburton, M.R. Reid, C.H. Stirling, G. Closs. “Validation of depth-profiling LA-ICP-MS in otolith
applications”. Canadian Journal of Fisheries and Aquatic Sciences. 2017. 74(4): 572-581.
doi:10.1139/cjfas-2016-0063.
18. L. Lobo, B. Fernández, R. Pereiro. “Depth profile analysis with glow discharge spectrometry”. Journal
of Analytical Atomic Spectrometry. 2017. 32(5): 920-930. doi:10.1039/c7ja00055c.
19. J. Kalvoda, T. Kumpan, M. Hola, O. Babek, V. Kanicky, R. Skoda. “Fine-scale LA-ICP-MS study of redox
oscillations and REEY cycling during the latest Devonian Hangenberg Crisis (Moravian Karst, Czech
Republic)”. Palaeogeography Palaeoclimatology Palaeoecology. 2018. 493: 30-43.
doi:10.1016/j.palaeo.2017.12.034.
20. S.F. Foley, D.E. Jacob, H.S.C. O'Neill. “Trace element variations in olivine phenocrysts from Ugandan
potassic rocks as clues to the chemical characteristics of parental magmas”. Contributions to
Mineralogy and Petrology. 2011. 162(1): 1-20. doi:10.1007/s00410-010-0579-y.
21. M. Danek, T. Bell, C.P. Laroque. “SOME CONSIDERATIONS IN THE RECONSTRUCTION OF LEAD LEVELS
USINGLASER ABLATION: LESSONS FROM THE DESIGN STAGE OF AN URBAN DENDROCHEMISTRY STUDY,
ST. JOHN'S, CANADA”. Geochronometria. 2015. 42(1): 217-231. doi:10.1515/geochr-2015-0024.
22. M. Sanborn, K. Telmer. “The spatial resolution of LA-ICP-MS line scans across heterogeneous
materials such as fish otoliths and zoned minerals”. Journal of Analytical Atomic Spectrometry. 2003.
18(10): 1231-1237. doi:10.1039/b302513f.
23. K. Proksova, K. Novotny, J. Kaiser, M. Galiova, T. Vaculovic, V. Kanicky. “Study of elemental
distribution in urinary stones by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LAICP-MS)”.
Journal of Biochemical Technology. 2010. 2(5): S106-S107.
24. A.G. Coedo, T. Dorado, I. Padilla, J.C. Fariñas. “Study of heterogeneities in steels and determination
of soluble and total aluminium and titanium concentration by laser ablation inductively coupled plasma
mass spectrometry”. Talanta. 2007. 71(5): 2108-2120. doi:10.1016/j.talanta.2006.10.027.
25. A.V. Izmer, M.V. Zoriy, C. Pickhardt, W. Quadakkers, V. Shemet, L. Singheiser, J.S. Becker. “LA-ICP-MS
studies of cross section of NiCrAlY-based coatings on high-temperature alloys”. Journal of Analytical
Atomic Spectrometry. 2005. 20(9): 918-923. doi:10.1039/b505459c.
26. C. Vlachou-Mogire, B. Stern, J.G. McDonnell. “The application of LA-ICP-MS in the examination of
the thin plating layers found in late Roman coins”. Nuclear Instruments & Methods in Physics Research
Section B-Beam Interactions with Materials and Atoms. 2007. 265(2): 558-568.
doi:10.1016/j.nimb.2007.09.040.
27. J.T. van Elteren, V.S. Selih, M. Sala. “Insights into the selection of 2D LA-ICP-MS (multi)elemental
mapping conditions”. Journal of Analytical Atomic Spectrometry. 2019. 34(9): 1919-1931.
doi:10.1039/c9ja00166b.
28. P.A. Doble, R.G. de Vega, D.P. Bishop, D.J. Hare, D. Clases. “Laser Ablation-Inductively Coupled
Plasma-Mass Spectrometry Imaging in Biology”. Chemical Reviews. 2021. 121(19): 11769-11822.
doi:10.1021/acs.chemrev.0c01219.
29. P. Stepka, M. Kratochvilova, M. Kuchynka, M. Raudenska, H.H. Polanska, T. Vicar, T. Vaculovic, M.
Vaculovicova, M. Masarik. “Determination of Renal Distribution of Zinc, Copper, Iron, and Platinum in
Mouse Kidney Using LA-ICP-MS”. Biomed Research International. 2021. 2021: 6800294.
doi:10.1155/2021/6800294.
30. Q.H. Luo, H.Z. Wang. “Elemental Quantitative Distribution and Statistical Analysis on Cross Section
of Stainless Steel Sheet by Laser Ablation Inductively Coupled Plasma Mass Spectrometry”. Journal of
Iron and Steel Research International. 2015. 22(8): 730-737. doi:10.1016/s1006-706x(15)30064-9.
31. T. Warchilová, V. Dillingerová, R. Skoda, T. Simo, O. Matal, T. Vaculovic, V. Kanicky. “Corrosion of
nickel-based structural materials for nuclear reactors by molten fluoride salt: From bulk content of
corrosion products to elemental imaging of corrosion changes”. Spectrochimica Acta Part B-Atomic
Spectroscopy. 2018. 148: 113-117. doi:10.1016/j.sab.2018.06.010.
32. S. Wagner, C. Hummel, J. Santner, M. Puschenreiter, J. Irrgeher, W.W. Wenzel, S.M. Borisov, T.
Prohaska. “<i>In situ</i> spatiotemporal solute imaging of metal corrosion on the example of
magnesium”. Analytica Chimica Acta. 2022. 1212: 339910. doi:10.1016/j.aca.2022.339910.
33. J.T. van Elteren, S. Panighello, V.S. Selih, E.F. Orsega. “Optimization of 2D LA-ICP-MS Mapping of
Glass with Decorative Colored Features: Application to Analysis of a Polychrome Vessel Fragment from
the Iron Age”. Recent Advances in Laser Ablation Icp-Ms for Archaeology. 2016. 53-71.
doi:10.1007/978-3-662-49894-1_4.
34. A. Gundlach-Graham, M. Burger, S. Allner, G. Schwarz, H.A.O. Wang, L. Gyr, D. Grolimund, B.
Hattendorf, D. Günther. “High-Speed, High-Resolution, Multielemental Laser Ablation-Inductively
Coupled Plasma-Time-of-Flight Mass Spectrometry Imaging: Part I. Instrumentation and TwoDimensional
Imaging of Geological Samples”. Analytical Chemistry. 2015. 87(16): 8250-8258.
doi:10.1021/acs.analchem.5b01196.
35. D. Chew, K. Drost, J.H. Marsh, J.A.Petrus. “LA-ICP-MS imaging in the geosciences and its applications
to geochronology”. Chemical Geology. 2021. 559: 119917. doi:10.1016/j.chemgeo.2020.119917.
36. M. Ohata, D. Tabersky, R. Glaus, J. Koch, B. Hattendorf, D. Gunther. “Comparison of 795 nm and 265
nm femtosecond and 193 nm nanosecond laser ablation inductively coupled plasma mass
spectrometry for the quantitative multi-element analysis of glass materials”. Journal of Analytical
Atomic Spectrometry. 2014. 29(8): 1345-1353. doi:10.1039/c4ja00030g.
37. H.R. Kuhn, D. Gunther. “Elemental fractionation studies in laser ablation inductively coupled plasma
mass spectrometry on laser-induced brass aerosols”. Analytical Chemistry. 2003. 75(4): 747-753.
doi:10.1021/ac0259919.
38. D. Bäuerle. Laser processing and chemistry. 2011.
39. R.E. Russo, X.L. Mao, J.J. Gonzalez, V. Zorba, J. Yoo. “Laser Ablation in Analytical Chemistry”.
Analytical Chemistry. 2013. 85(13): 6162-6177. doi:10.1021/ac4005327.
40. K.H. Leitz, B. Redlingshofer, Y. Reg, A. Otto, M. Schmidt. “Metal Ablation with Short and Ultrashort
Laser Pulses”. Lasers in Manufacturing 2011: Proceedings of the Sixth International Wlt Conference on
Lasers in Manufacturing, Vol 12, Pt B. 2011. 12: 230-238. doi:10.1016/j.phpro.2011.03.128.
41. P.M. Outridge, W. Doherty, D.C. Gregoire. “Ablative and transport fractionation of trace elements
during laser sampling of glass and copper”. Spectrochimica Acta Part B-Atomic Spectroscopy. 1997.
52(14): 2093-2102. doi:10.1016/s0584-8547(97)00112-2.
42. M. Hola, V. Otruba, V. Kanicky. “Influence of binders on infrared laser ablation of powdered tungsten
carbide pressed pellets in comparison with sintered tungsten carbide hardmetals studied by inductively
coupled plasma atomic emission spectrometry”. Spectrochimica Acta Part B-Atomic Spectroscopy.
2006. 61(5): 515-524. doi:10.1016/j.sab.2006.03.007.
43. D. Marla, U.V. Bhandarkar, S.S. Joshi. “A model of laser ablation with temperature-dependent
material properties, vaporization, phase explosion and plasma shielding”. Applied Physics a-Materials
Science & Processing. 2014. 116(1): 273-285. doi:10.1007/s00339-013-8118-0.
44. B.J. Fryer, S.E. Jackson, H.P. Longerich. “DESIGN, OPERATION AND ROLE OF THE LASER-ABLATION
MICROPROBE COUPLED WITH AN INDUCTIVELY-COUPLED PLASMA - MASS-SPECTROMETER (LAM-ICPMS)
IN THE EARTH-SCIENCES”. Canadian Mineralogist. 1995. 33: 303-312.
45. M. Guillong, I. Horn, D. Gunther. “A comparison of 266 nm, 213 nm and 193 nm produced from a
single solid state Nd : YAG laser for laser ablation ICP-MS”. Journal of Analytical Atomic Spectrometry.
2003. 18(10): 1224-1230. doi:10.1039/b305434a.
46. O.V. Borisov, X.L. Mao, R.E. Russo. “Effects of crater development on fractionation and signal
intensity during laser ablation inductively coupled plasma mass spectrometry”. Spectrochimica Acta
Part B-Atomic Spectroscopy. 2000. 55(11): 1693-1704. doi:10.1016/s0584-8547(00)00272-x.
47. R. Glaus, R. Kaegi, F. Krumeich, D. Gunther. “Phenomenological studies on structure and elemental
composition of nanosecond and femtosecond laser-generated aerosols with implications on laser
ablation inductively coupled plasma mass spectrometry”. Spectrochimica Acta Part B-Atomic
Spectroscopy. 2010. 65(9-10): 812-822. doi:10.1016/j.sab.2010.07.005.
48. R. Jaworski, E. Hoffmann, H. Stephanowitz. “Collection and separation of particles by size from laser
ablated material”. International Journal of Mass Spectrometry. 2002. 219(2): 373-379.
doi:10.1016/s1387-3806(02)00768-6.
49. H.R. Kuhn, J. Koch, R. Hargenroder, K. Niemax, M. Kalberer, D. Gunther. “Evaluation of different
techniques for particle size distribution measurements on laser-generated aerosols”. Journal of
Analytical Atomic Spectrometry. 2005. 20(9): 894-900. doi:10.1039/b504563k.
50. E.C. Hathorne, R.H. James, P. Savage, O. Alard. “Physical and chemical characteristics of particles
produced by laser ablation of biogenic calcium carbonate”. Journal of Analytical Atomic Spectrometry.
2008. 23(2): 240-243. doi:10.1039/b706727e.
51. J. Kosler, M. Wiedenbeck, R. Wirth, J. Hovorka, P. Sylvester, J. Mikova. “Chemical and phase
composition of particles produced by laser ablation of silicate glass and zircon - implications for
elemental fractionation during ICP-MS analysis”. Journal of Analytical Atomic Spectrometry. 2005.
20(5): 402-409. doi:10.1039/b41629b.
52. G. Alloncle, N.Gilon, C.Legens, C.P.Lienemann, B. Rebours, L.Sorbier, S. Morin, R. Revel. “Following
the evolution of morphology, composition and crystallography of alumina based catalysts after laser
ablation: Implications for analysis by LA-ICP-AES”. Applied Surface Science. 2009. 255(22): 8978-8985.
doi:10.1016/j.apsusc.2009.05.160.
53. D. Fliegel, M. Klementova, J. Kosler. “Phase and Composition Changes of Titanite during Laser
Ablation Inductively Coupled Plasma Mass Spectrometry Analysis”. Analytical Chemistry. 2010. 82(10):
4272-4277. doi:10.1021/ac902284y.
54. E.O. Knutson, Whitby, K.T. “Aerosol classification by electric mobility: apparatus, theory, and
applications”. 1975. 6: 443-451.
55. A. Wiedensohler, A. Wiesner, K. Weinhold, W. Birmili, M. Hermann, M. Merkel, T. Muller, S. Pfeifer,
A. Schmidt, T. Tuch, F. Velarde, P. Quincey, S. Seeger, A. Nowak. “Mobility particle size spectrometers:
Calibration procedures and measurement uncertainties”. Aerosol Science and Technology. 2018. 52(2):
146-164. doi:10.1080/02786826.2017.1387229.
56. H. Tammet, A. Mirme, E. Tamm. “Electrical aerosol spectrometer of Tartu University”. Atmospheric
Research. 2002. 62(3-4): 315-324. doi:10.1016/s0169-8095(02)00017-0.
57. W.W. Szymanski, A. Nagy, A. Czitrovszky. “Optical particle spectrometry-Problems and prospects”.
Journal of Quantitative Spectroscopy & Radiative Transfer. 2009. 110(11): 918-929.
doi:10.1016/j.jqsrt.2009.02.024.
58. A. Berner, C. Lurzer, F. Pohl, O. Preining, P. Wagner. “SIZE DISTRIBUTION OF THE URBAN AEROSOL
IN VIENNA”. Science of the Total Environment. 1979. 13(3): 245-261. doi:10.1016/0048-
9697(79)90105-0.
59. D.W. Lee, M.D. Cheng. “Particle generation by ultraviolet-laser ablation during surface
decontamination”. Journal of the Air & Waste Management Association. 2006. 56(11): 1591-1598.
60. Z. Marton, L. Landstrom, M. Boman, P. Heszler. “A comparative study of size distribution of
nanoparticles generated by laser ablation of graphite and tungsten”. Materials Science & Engineering
C-Biomimetic and Supramolecular Systems. 2003. 23(1-2): 225-228. doi:10.1016/s0928-
4931(02)00272-2.
61. B.P. Lee, Y.J. Li, R.C. Flagan, C. Lo, C.K. Chan. “Sizing Characterization of the Fast-Mobility Particle
Sizer (FMPS) Against SMPS and HR-ToF-AMS”. Aerosol Science and Technology. 2013. 47(9): 1030-1037.
doi:10.1080/02786826.2013.810809.
62. C. Paton, J.D. Woodhead, J.C. Hellstrom, J.M. Hergt, A. Greig, R. Maas. “Improved laser ablation UPb
zircon geochronology through robust downhole fractionation correction”. Geochemistry Geophysics
Geosystems. 2010. 11: Q0aa06. doi:10.1029/2009gc002618.
63. X. Lin, W. Guo, L.L. Jin, S.H. Hu. “Review: Elemental Analysis of Individual Fluid Inclusions by Laser
Ablation-ICP-MS”. Atomic Spectroscopy. 2020. 41(1): 1-10. doi:10.46770/as.2020.01.001.
64. C. Paton, J. Hellstrom, B. Paul, J. Woodhead, J. Hergt. “Iolite: Freeware for the visualisation and
processing of mass spectrometric data”. Journal of Analytical Atomic Spectrometry. 2011. 26(12): 2508-
2518. doi:10.1039/c1ja10172b.
65. V. Faltusova, T. Vaculovic, M. Hola, V. Kanicky. “Ilaps - python software for data reduction and
imaging with LA-ICP-MS”. Journal of Analytical Atomic Spectrometry. 2022. 37(4): 733-740.
doi:10.1039/d1ja00383f.
66. O. Branson, J.S. Fehrenbacher, L. Vetter, A.Y. Sadekov, S.M. Eggins, H.J. Spero. “<i>LAtools</i>: A
data analysis package for the reproducible reduction of LA-ICPMS data”. Chemical Geology. 2019. 504:
83-95. doi:10.1016/j.chemgeo.2018.10.029.
67. J.C. Wright, M.J. Wirth. “PRINCIPLES OF LASERS”. Analytical Chemistry. 1980. 52(9): 1087-1095.
doi:10.1021/ac50059a004.
68. D. Figg, M.S. Kahr. “Elemental fractionation of glass using laser ablation inductively coupled plasma
mass spectrometry”. Applied Spectroscopy. 1997. 51(8): 1185-1192. doi:10.1366/0003702971941728.
69. T.E. Jeffries, W.T. Perkins, N.J.G. Pearce. “COMPARISONS OF INFRARED AND ULTRAVIOLET-LASER
PROBE MICROANALYSIS INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY IN MINERAL
ANALYSIS”. Analyst. 1995. 120(5): 1365-1371. doi:10.1039/an9952001365.
70. C.Y. Liu, X.L. Mao, J. Gonzalez, R.E. Russo. “Study of particle size infkuence on laser ablation
inductively coupled plasma mass spectrometry using an in-line cascade impactor”. Journal of Analytical
Atomic Spectrometry. 2005. 20(3): 200-203. doi:10.1039/b414422h.
71. S.D. Zhang, M.H. He, Z.B. Yin, E.Y. Zhu, W. Hang, B.L. Huang. “Elemental fractionation and matrix
effects in laser sampling based spectrometry”. Journal of Analytical Atomic Spectrometry. 2016. 31(2):
358-382. doi:10.1039/c5ja00273g.
72. P.K. Diwakar, S.S. Harilal, N.L. LaHaye, A. Hassanein, P. Kulkarni. “The influence of laser pulse
duration and energy on ICP-MS signal intensity, elemental fractionation, and particle size distribution
in NIR fs-LA-ICP-MS”. Journal of Analytical Atomic Spectrometry. 2013. 28(9): 1420-1429.
doi:10.1039/c3ja50088h.
73. C. Liu, X.L. Mao, S.S. Mao, X. Zeng, R. Greif, R.E.Russo. “Nanosecond and ferntosecond laser ablation
of brass: Particulate and ICPMS measurements”. Analytical Chemistry. 2004. 76(2): 379-383.
doi:10.1021/ac035040a.
74. R. Hergenroder. “A model of non-congruent laser ablation as a source of fractionation effects in LAICP-MS”.
Journal of Analytical Atomic Spectrometry. 2006. 21(5): 505-516. doi:10.1039/b600698a.
75. R. Hergenroder. “Hydrodynamic sputtering as a possible source for fractionation in LA-ICP-MS”.
Journal of Analytical Atomic Spectrometry. 2006. 21(5): 517-524. doi:10.1039/b600705h.
76. H.R. Kuhn, D. Gunther. “Laser ablation-ICP-MS: particle size dependent elemental composition
studies on filter-collected and online measured aerosols from glass”. Journal of Analytical Atomic
Spectrometry. 2004. 19(9): 1158-1164. doi:10.1039/b404729j.
77. Q.Z. Bian, C.C. Garcia, J. Koch, K. Niemax. “Non-matrix matched calibration of major and minor
concentrations of Zn and Cu in brass, aluminium and silicate glass using NIR femtosecond laser ablation
inductively coupled plasma mass spectrometry”. Journal of Analytical Atomic Spectrometry. 2006.
21(2): 187-191. doi:10.1039/b513690c.
78. H.R. Kuhn, M. Guillong, D. Gunther. “Size-related vaporisation and ionisation of laser-induced glass
particles in the inductively coupled plasma”. Analytical and Bioanalytical Chemistry. 2004. 378(4): 1069-
1074. doi:10.1007/s00216-003-2346-7.
79. X.L. Mao, W.T. Chan, M. Caetano, M.A. Shannon, R.E. Russo. “Preferential vaporization and plasma
shielding during nano-second laser ablation”. Applied Surface Science. 1996. 96-8: 126-130.
doi:10.1016/0169-4332(95)00420-3.
80. T. Ohkubo, M. Kuwata, B. Luk'yanchuk, T. Yabe. “Numerical analysis of nanocluster formation within
ns-laser ablation plume”. Applied Physics a-Materials Science & Processing. 2003. 77(2): 271-275.
doi:10.1007/s00339-003-2135-3.
81. H.R. Kuhn, D. Gunther. “The agglomeration state of nanosecond laser-generated aerosol particles
entering the ICP”. Analytical and Bioanalytical Chemistry. 2005. 383(3): 434-441. doi:10.1007/s00216-
005-0021-x.
82. S.W. Zeng, D. Baillargeat, H.P. Ho, K.T. Yong. “Nanomaterials enhanced surface plasmon resonance
for biological and chemical sensing applications”. Chemical Society Reviews. 2014. 43(10): 3426-3452.
doi:10.1039/c3cs60479a.
6 Abbreviations
APS Aerodynamic Particle Sizer
BSE Back-Scattered Electrons
CPC Condensation Particle Counter
CPS Counts Per Second
Dm Mobility diameter (measured by Differential Mobility Analyser)
DMA Differential Mobility Analyser
EEPS Engine Exhaust Particle Sizer
EDS Energy Dispersive X-ray Spectroscopy
EDX Energy Dispersive X-ray Spectroscopy
EPMA Electron Probe Micro Analysis
FI Fractionation Index
FMPS Fast Mobility Particle Sizer
ICP Inductively Coupled Plasma
ICP-MS Inductively Coupled Plasma Mass Spectrometry
LA Laser Ablation
LA-Q-ICP-MS LaserAblationwith Quadrupole InductivelyCoupledPlasma Mass Spectrometry
LA-ICP-MS Laser Ablation with Inductively Coupled Plasma Mass Spectrometry
LOD Limit of Detection
Nd:YAG Neodymium-doped Yttrium Aluminium Garnet; Nd:Y3Al5O12
NE-LA Nanoparticle-Enhanced Laser Ablation
NP Nanoparticle
OPC Optical Particle Counter
OPS Optical Particle Sizer
PIXE Particle-induced X-ray Emission
PNC Particle Number Concentration
PSD Particle Size Distribution
SD Standard Deviation
SEM Scanning Electron Microscopy
SMPS Scanning Mobility Particle Sizer
SRM Standard Reference Material
TEM Transmission Electron Microscopy
7 Attachment
The appendix contains a set of papers commentingon this habilitationthesis in the order listed
in Chapter 1.2.
Paper 1…………………………………………………………………….………….…...…..52
Paper 2……………………………………………..………………………………....…...…..68
Paper 3………………………………………………………………………………..…...…..78
Paper 4……………………………………………………………………………….…....…..90
Paper 5……………………………………………………………………………….…....…..99
Paper 6……………………………………………………………………………….…...….107
Paper 7…………………………………………………………………………….....…...….117
Paper 8…………………………………………………………………………...…..…...….127
Paper 9…………………………………………………………………………………....….140
Paper 10..………………………………………………………….………...……….…...….151
Paper 11…………………………………………………………………………………..….161
Paper 12………………………………………………………………………………......….168
Trace element signatures of uraninite controlled by fluid-rock interactions: A
case study from the Eastern Moldanubicum (Bohemian Massif)
Wertich, V.*, Kubeš, M., Leichmann, J., Holá, M., Haifler, J., Mozola, J., Hršelová, P., Jaroš, M.
Journal of Geochemical Exploration. 2022, 243, 107111. DOI 10.1016/j.gexplo.2022.107111
Contribution:
LA-ICP-MS design of experiments and measurements, data evaluation, participation in
manuscript writing.
Possibilities of LA-ICP-MS technique for the spatial elemental analysis of the
recent fish scales: Line scan vs. depth profiling
Holá, M., Kalvoda, J.*, Nováková, H., Škoda, R., Kanický
Applied Surface Science. 2011, 257(6), 1932-1940. DOI 10.1016/j.apsusc.2010.09.029
Contribution:
LA-ICP-MS design of experiments and measurements, data evaluation, participation in
manuscript writing.
Dual imaging of uranium ore by Laser Ablation Inductively Coupled Plasma
Mass Spectrometry and Laser Induced Breakdown Spectroscopy
Holá, M., Novotný, K.*, Dobeš, J., Krempl, I., Wertich, V., Mozola, J., Kubeš, M., Faltusová, V.,
Leichmann, J., Kanický
Spectrochimica Acta Part B. 2021, 186, 106312. DOI 10.1016/j.sab.2021.106312
Contribution:
LA-ICP-MS design of experiments and measurements, data evaluation, graphic processing,
manuscript writing.
Quantitative analysis of Fe-based samples using ultraviolet nanosecond and
femtosecond laser ablation-ICP-MS
Možná, V., Pisonero, J.*, Holá, M., Kanický, V., Günther, D.
Journal of Analytical Atomic Spectrometry. 2006, 21(11), 1194–1201. DOI 10.1039/b606988f
Contribution:
Student supervision, consultation (the work was developed at ETH Zurich).
Feasibility of Nanoparticle-Enhanced Laser Ablation Inductively Coupled
Plasma Mass Spectrometry
Holá, M., Salajková,Z., Hrdlička,A., Pořízka,P., Novotný,K., Čelko, L., Šperka,P., Prochazka,D.,
Novotný, J., Modlitbová, P., Kanický, Kaiser, J.
Analytical Chemistry. 2018, 90(20), 11820–11826. DOI 10.1021/acs.analchem.8b01197
Contribution:
Design of experiments, LA-ICP-MS measurements, data evaluation, manuscript writing.
Influence of sample surface topography on laser ablation process
Salajková, Z.*, Holá, M., Prochazka, D., Ondráček, J., Pavliňák, D., Čelko, L., Gregar, F., Šperka,
P., Pořízka, P., Kanický, De Giacomo, A., Kaiser, J.
Talanta 222 (2021) 121512, DOI 10.1016/j.talanta.2020.121512
Contribution:
LA-ICP-MS design of experiments and measurements, data evaluation, manuscript writing.
Online monitoring of nanoparticles formed during nanosecond laser ablation
Nováková, H., Holá, M.*, Vojtíšek-Lom, M., Ondráček, J., Kanický, V.
Spectrochimica Acta Part B. 2016, 125, 52–60. DOI 10.1016/j.sab.2016.09.017
Contribution:
LA-ICP-MS and aerosol design ofexperiments and measurements,data evaluation,studyingof
ablation craters and the particle structure, manuscript writing, corresponding author.
The influence of material properties on highly time resolved particle formation
for nanosecond laser ablation
Holá, M.*, Ondráček, J., Nováková, H., Vojtíšek-Lom, M., Hadravová, R., Kanický, V.
Spectrochimica Acta Part B. 2018, 148, 193–204, DOI 10.1016/j.sab.2018.07.001
Contribution:
LA-ICP-MS and aerosol design ofexperiments and measurements,data evaluation,studyingof
ablation craters and the particle structure, manuscript writing, corresponding author.
Influence of physical properties and chemical composition of sample on
formation of aerosol particles generated by nanosecond laser ablation at
213 nm
Holá, M.*, Konečná, V., Mikuška, P., Kaiser, J., Kanický, V.
Spectrochimica Acta Part B. 2010, 65(1), 51–60. DOI 10.1016/j.sab.2009.11.003
Contribution:
LA-ICP-MS and aerosol design ofexperiments and measurements,data evaluation,studyingof
ablation craters and the particle structure, manuscript writing, corresponding author.
Study of aerosols generated by 213 nm laser ablation of cobalt-cemented hard
metals
Holá, M.*, Konečná, V., Mikuška, P., Kaiser, J.*, Páleníková, K., Průša, S., Hanzlíková, R.,
Kanický, V.
Journal of Analytical Atomic Spectrometry. 2008, 23(10), 1341–1349. DOI 10.1039/B802906G
Contribution:
LA-ICP-MS and aerosol design ofexperiments and measurements,data evaluation,studyingof
ablation craters and the particle structure, manuscript writing, corresponding author.
Tungsten carbide precursors as an example for influence of a binder on the
particle formation in the nanosecond laser ablation of powdered materials
Holá, M.*, Mikuška, P., Hanzlíková, R., Kaiser, J., Kanický, V.
Talanta. 2010, 80(5), 1862–1867. DOI 10.1016/j.talanta.2009.10.035
Contribution:
LA-ICP-MS design of experiments and measurements, data evaluation, studying of ablation
craters, trappingparticles on the filter and studyingthe particle structure,manuscript writing,
corresponding author.
The effect of nanoparticle presence on aerosol formation during nanoparticleenhanced
laser ablation inductively coupled plasma mass spectrometry
Holá, M., Salajková,Z., Hrdlička, A.*, M., Ondráček, J., Novotný, K., Pavliňák,D., Vojtíšek-Lom,
M., Čelko, L., Pořízka, P., Kanický, V., Prochazka, D., Novotný, J., Kaiser, J.
Journal of Analytical Atomic Spectrometry. 2020, 35(12), 2893-2900. DOI 10.1039/d0ja00324g
Contribution:
LA-ICP-MS design of experiments and measurements, data evaluation, studying of ablation
craters, trappingparticles on the filter and studyingthe particle structure,manuscript writing.