Decreasing the laser radiation absorption in the plasma plume and improving the sensitivity in quantitative laser microspectral analysis

• Published in: Spectrochimica acta. Part B: Atomic spectroscopy 1984, Vol.39 (9), p.1209-1219
• Main Authors: Dimitrov, G., Zheleva, Ts
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Spectrometric and optical methods
• ISSN: 0584-8547; 1873-3565
• DOI: 10.1016/0584-8547(84)80207-4

Results from investigations along two lines are presented: a study of the screening effect of the laser induced microplasma and the possibility of improving the limit of detection, the concentration sensitivity and reproducibility in laser microspectral analysis. Cross-sectional probing of the laser induced plasma plume is achieved with a deviated part of the laser beam, evaporating the substance. The absorbance of the plasma generated by different substances at different heights above the sample surface for a fixed laser energy has been studied as well. It has been established that laser energy absorption in the plasma plume decreases when the sample is inclined with respect to the laser radiation direction. This is due to the shorter path of the laser radiation in the plasma plume formed by the vertical take-off of the erosion products from the sample. A larger substance quantity is evaporated as a result of decreased absorption in the laser plume and the spectra obtained are more intense. The limits of detection for the elements are improved as well as the concentration sensitivity and reproducibility in laser microspectral analysis.