Conditional data processing for single-shot spectral analysis by use of laser-induced breakdown spectroscopy

2003 ◽  
Vol 42 (30) ◽  
pp. 6022 ◽  
Author(s):  
Jorge E. Carranza ◽  
Kenjiro Iida ◽  
David W. Hahn
2019 ◽  
Vol 74 (1) ◽  
pp. 42-54 ◽  
Author(s):  
Daniel Diaz ◽  
Alejandro Molina ◽  
David W. Hahn

Laser-induced breakdown spectroscopy (LIBS) and principal component analysis (PCA) were applied to the classification of LIBS spectra from gold ores prepared as pressed pellets from pulverized bulk samples. For each sample, 5000 single-shot LIBS spectra were obtained. Although the gold concentrations in the samples were as high as 7.7 µg/g, Au emission lines were not observed in most single-shot LIBS spectra, rendering the application of the usual ensemble-averaging approach for spectral processing to be infeasible. Instead, a PCA approach was utilized to analyze the collection of single-shot LIBS spectra. Two spectral ranges of 21 nm and 0.15 nm wide were considered, and LIBS variables (i.e., wavelengths) reduced to no more than three principal components. Single-shot spectra containing Au emission lines (positive spectra) were discriminated by PCA from those without the spectral feature (negative spectra) in a spectral range of less than 1 nm wide around the Au(I) 267.59 nm emission line. Assuming a discrete gold distribution at very low concentration, LIBS sampling of gold particles seemed unlikely; therefore, positive spectra were considered as data outliers. Detection of data outliers was possible using two PCA statistical parameters, i.e., sample residual and Mahalanobis distance. Results from such a classification were compared with a standard database created with positive spectra identified with a filtering algorithm that rejected spectra with an Au intensity below the smallest detectable analytical LIBS signal (i.e., below the LIBS limit of detection). The PCA approach successfully identified 100% of the data outliers when compared with the standard database. False identifications in the multivariate approach were attributed to variations in shot-to-shot intensity and the presence of interfering emission lines.


2013 ◽  
Vol 60 (21) ◽  
pp. 1905-1909 ◽  
Author(s):  
W.F. Luo ◽  
X.X. Zhao ◽  
H.Y. Zhu ◽  
D.H. Xie ◽  
J. Liu ◽  
...  

2019 ◽  
Vol 34 (6) ◽  
pp. 1047-1082 ◽  
Author(s):  
Sahar Sheta ◽  
Muhammad Sher Afgan ◽  
Zongyu Hou ◽  
Shun-Chun Yao ◽  
Lei Zhang ◽  
...  

This review article forms a guideline for LIBS contribution in coal analysis, encompassing fundamental aspects, operation modes, data processing, and analytical results. LIBS applications related to coal utilization are also highlighted (fly ash analysis and combustion monitoring).


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