Laser-induced breakdown spectroscopy (LIBS) data obtained from the elemental imaging of heterogenous samples were processed with various chemometric algorithms. The intention was to cluster obtained characteristic spectra and to provide additional information about the sample surface composition and distribution of individual matrices. However, there is a gray zone on the boundary of two matrices and the consequent clustering of the spectra obtained on this boundary is ambiguous. This paper focuses on the transition between two well-defined matrices in a simplified case for a better transparency in data visualization. Steel and aluminum samples that are represented by characteristic spectra with significantly distinct structures (e.g., different number of spectral lines). Using a carefully designed experiment, several Fe:Al ratios were ablated and analyzed by principal component analysis (PCA), self-organizing maps (SOM), and standard data metrics. This paper shows the strategy for the discrimination of unrecognized spectra and possibilities in their clustering.
MiziolekA.W.PalleschiV.SchechterI.. Laser Induced Breakdown Spectroscopy: Fundamentals and Applications. Cambridge, UK: Cambridge University Press, 2006.
3.
RehseS.J.SalimniaH.MiziolekA.W.. “Laser-Induced Breakdown Spectroscopy (LIBS): An Overview of Recent Progress and Future Potential for Biomedical Applications”. J. Med. Eng. 2012. 36: 77–89. doi: 10.3109/03091902.2011.645946.
4.
HarmonR.S.RussoR.E.HarkR.R.. “Applications of Laser-Induced Breakdown Spectroscopy for Geochemical and Environmental Analysis: A Comprehensive Review”. Spectrochim. Acta, Part B. 2013. 87: 11–26. doi: 10.1016/J.Sab.2013.05.017.
5.
NollR.Fricke-BegemannC.BrunkM.ConnemannS., et al. “Laser-Induced Breakdown Spectroscopy Expands into Industrial Applications”. Spectrochim. Acta, Part B. 2014. 93: 41–51. doi: 10.1016/J.Sab.2014.02.001.
6.
GuoJ.LuY.ChengK.SongJ., et al. “Development of a Compact Underwater Laser-Induced Breakdown Spectroscopy (LIBS) System and Preliminary Results in Sea Trials”. Appl. Opt. 2017. 56(29): 8196–8200. doi: 10.1364/OE.22.003895.
7.
MauriceS.CleggS. M.WiensR. C.GasnaultO., et al. “ChemCam Activities and Discoveries During the Nominal Mission of the Mars Science Laboratory in Gale Crater, Mars”. J. Anal. At. Spectrom. 2016. 31(4): 863–889. doi: 10.1039/C5ja00417a.
8.
WiensR. C.MauriceS.BarracloughB.SaccoccioM., et al. “The ChemCam Instrument Suite on the Mars Science Laboratory (MSL) Rover: Body Unit and Combined System Tests”. Space Sci. Rev. 2012. 170(1–4): 167–227. doi: 10.1007/S11214-012-9902-4.
9.
JolivetL.LeprinceM.MoncayoS.SorbierL., et al. “Review of the Recent Advances and Applications of LIBS-Based Imaging”. Spectrochim. Acta, Part B. 2019. 151: 41–53. 10.1016/J.Sab.2018.11.008.
10.
PořízkaP.KlusJ.KépešE.ProchazkaD., et al. “On the Utilization of Principal Component Analysis in Laser-Induced Breakdown Spectroscopy Data Analysis, a Review”. Spectrochim. Acta, Part B. 2018. 148: 65–82. doi: 10.1016/J.Sab.2018.05.030.
11.
El HaddadJ.CanioniL.BousquetB.. “Good practices in LIBS analysis: Review and advices”. Spectrochim. Acta, Part B. 2014. 101: 171–182. doi: 10.1016/J.Sab.2014.08.039.
VrábelJ.KépešE.DuponchelL.Motto-RosV., et al. “Classification of challenging Laser-Induced Breakdown Spectroscopy soil sample data - EMSLIBS contest”. Spectrochim. Acta, Part B. 2020. 169: 105872. doi: 10.1016/J.Sab.2020.105872.
14.
CuiX.WangQ.ZhaoY.QiaoX., et al. “Laser-Induced Breakdown Spectroscopy (LIBS) for Classification of Wood Species Integrated with Artificial Neural Network (ANN)”. Appl. Phys. B. 2019. 125: 56. doi: 10.1007/S00340-019-7166-3.
15.
BetteH.NollR.. “High Speed Laser-Induced Breakdown Spectrometry for Scanning Microanalysis”. J. Phys. D: Appl. Phys. 2004. 37(8): 1281–1288. doi: 10.1088/0022-3727/37/8/018.
16.
MenutD.FichetP.LacourJ.-L.RivoallanA., et al. “Micro-Laser-Induced Breakdown Spectroscopy Technique: A Powerful Method for Performing Quantitative Surface Mapping on Conductive and Nonconductive Samples”. Appl. Opt. 2003. 42(30): 6063–6071. doi: 10.1364/AO.42.006063.
17.
LucenaP.VadilloJ.M.LasernaJ.J.. “Mapping of Platinum Group Metals in Automotive Exhaust Three-Way Catalysts Using Laser-Induced Breakdown Spectrometry”. Anal. Chem. 1999. 71(19): 4385–4391. doi: 10.1021/Ac9902998.
18.
RomeroD.LasernaJ.J.. “Multielemental Chemical Imaging Using Laser-Induced Breakdown Spectrometry”. Anal. Chem. 1997. 69(15): 2871–2876. doi: 10.1021/ac970311.
19.
RomeroD.LasernaJ.J.. “A Microanalytical Study of Aluminium Diffusion in Photovoltaic Cells Using Imaging-Mode Laser-Induced Breakdown Spectrometry”. Spectrochim. Acta, Part B. 2000. 55(8): 1241–1248. doi: 10.1016/S0584-8547(00)00204-4.
20.
LimbeckA.BrunnbauerL.LohningerH.PořízkaP., et al. “Methodology and Applications of Elemental Mapping by Laser Induced Breakdown Spectroscopy”. Anal. Chim. Acta. 2021. 1147: 72–98. doi: 10.1016/J.Aca.2020.12.054.
21.
Motto-RosV.MoncayoS.TrichardF.PelasciniF.. “Investigation of Signal Extraction in the Frame of Laser Induced Breakdown Spectroscopy Imaging”. Spectrochim. Acta, Part B. 2019. 155: 127–133. doi: 10.1016/J.Sab.2019.04.004.
22.
BasselL.Motto-RosV.TrichardF.PelasciniF., et al. “Laser-Induced Breakdown Spectroscopy for Elemental Characterization of Calcitic Alterations on Cave Walls”. Environ. Sci. Pollut. Res. 2017. 24(3): 2197–2204. doi: 10.1007/S11356-016-7468-5.
23.
SytaO.WagnerB.BulskaE.ZielińskaD., et al. “Elemental Imaging of Heterogeneous Inorganic Archaeological Samples by Means of Simultaneous Laser Induced Breakdown Spectroscopy and Laser Ablation Inductively Coupled Plasma Mass Spectrometry Measurements”. Talanta. 2018. 179: 784–791. doi: 10.1016/J.Talanta.2017.12.011.
24.
MoncayoS.TrichardF.BusserB.Sabatier-VincentM., et al. “Multi-Elemental Imaging of Paraffin-Embedded Human Samples by Laser-Induced Breakdown Spectroscopy”. Spectrochim. Acta, Part B. 2017. 133: 40–44. doi: 10.1016/J.Sab.2017.04.013.
25.
BusserB.MoncayoS.CollJ.-L.SanceyL., et al. “Elemental Imaging Using Laser-Induced Breakdown Spectroscopy: A New and Promising Approach for Biological and Medical Applications”. Coord. Chem. Rev. 2018. 358: 70–79. doi: 10.1016/J.Ccr.2017.12.006.
26.
RomppanenS.HäkkänenH.KekkonenJ.NissinenJ., et al. “Time‐gated Raman and laser‐induced breakdown spectroscopy in mapping of eudialyte and catapleiite”. J. Raman Spectrosc. 2020. 51(9): 1462–1469. doi: 10.1002/Jrs.5622.
27.
KlusJ.MikysekP.ProchazkaD.PořízkaP., et al. “Multivariate Approach to the Chemical Mapping of Uranium in Sandstone-Hosted Uranium Ores Analyzed Using Double Pulse Laser-Induced Breakdown Spectroscopy”. Spectrochim. Acta, Part B. 2016. 123: 143–149. doi: 10.1016/J.Sab.2016.08.014.
28.
WangX.Motto-RosV.PanczerG.de LignyD., et al. “Mapping of Rare Earth Elements in Nuclear Waste Glass-Ceramic Using Micro Laser-Induced Breakdown Spectroscopy”. Spectrochim. Acta, Part B. 2013. 87: 139–146. doi: 10.1016/J.Sab.2013.05.022.
29.
BetteH.NollR.. “High Speed Laser-Induced Breakdown Spectrometry for Scanning Microanalysis”. J. Phys. D: Appl. Phys. 2004. 37(8): 1281–1288. doi: 10.1088/0022-3727/37/8/018.
30.
MoncayoS.DuponchelL.MousavipakN.PanczerG., et al. “Exploration of Megapixel Hyperspectral LIBS Images Using Principal Component Analysis”. J. Anal. At. Spectrom. 2018. 33(2): 210–220. doi: 10.1039/C7JA00398F.
31.
RomppanenS.HäkkänenH.KaskiS.. “Singular Value Decomposition Approach to the Yttrium Occurrence in Mineral Maps of Rare Earth Element Ores Using Laser-Induced Breakdown Spectroscopy”. Spectrochim. Acta, Part B. 2017. 134: 69–74. doi: 10.1016/J.Sab.2017.06.002.
32.
KlusJ.PořízkaP.ProchazkaD.MikysekP., et al. “Application of Self-Organizing Maps to the Study of U-Zr-Ti-Nb Distribution in Sandstone-Hosted Uranium Ores”. Spectrochim. Acta, Part B. 2017. 131: 66–73. doi: 10.1016/J.Sab.2017.03.008.
33.
NardecchiaA.FabreC.CauzidJ.PelasciniF.. et al. “Detection of Minor Compounds in Complex Mineral Samples from Millions of Spectra: A New Data Analysis Strategy in LIBS Imaging”. Anal. Chim. Acta. 2020. 1114: 66–73. doi: 10.1016/J.Aca.2020.04.005.
34.
KohonenT.. “The Self-Organizing Map”. Proc. IEEE. 1990. 78(9): 1464–1480. doi: 10.1109/5.58325.
35.
ProchazkaD.MazuraM.SamekO.RebrošováK., et al. “Combination of Laser-Induced Breakdown Spectroscopy and Raman Spectroscopy for Multivariate Classification of Bacteria”. Spectrochim. Acta, Part B. 2018. 139: 6–12. doi: 10.1016/J.Sab.2017.11.004.
