Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) with Standard Reference Line for the Analysis of...

Area of Science:

• Analytical Chemistry
• Materials Science
• Spectroscopy

Background:

• Laser-induced breakdown spectroscopy (LIBS) is a powerful technique for elemental analysis.
• Self-absorption of spectral lines, particularly for major elements like Iron (Fe), complicates accurate plasma characterization and trace element quantification in LIBS.
• Constructing Boltzmann plots for all species is challenging due to sparse spectral lines of trace elements and self-absorption effects.

Purpose of the Study:

• To develop and validate a novel standard reference line method for calibration-free laser-induced breakdown spectroscopy (CF-LIBS).
• To accurately determine plasma temperature and electron density in CF-LIBS analysis of stainless steel.
• To effectively mitigate the adverse effects of spectral self-absorption on trace element analysis.

Main Methods:

• Utilized calibration-free laser-induced breakdown spectroscopy (CF-LIBS) on a certified stainless steel sample.
• Proposed a standard reference line method assuming local thermodynamic equilibrium to determine plasma parameters.
• Employed Stark broadening of Fe(I) 381.584 nm and Saha-Boltzmann plots of Fe for electron density and plasma temperature calculation.
• Implemented a pre-selection procedure to eliminate self-absorbed spectral lines before trace element concentration determination.

Main Results:

• Successfully calculated electron density and plasma temperature using Fe spectral lines, accounting for self-absorption.
• Determined trace element concentrations by selecting a single spectral line per element.
• Demonstrated effective avoidance of self-absorption's adverse effects on elemental analysis.
• Compared results obtained using standard reference lines with and without self-absorption.

Conclusions:

• The proposed standard reference line method enhances the accuracy of CF-LIBS analysis, especially for complex matrices like stainless steel.
• This method provides a reliable approach for accurate plasma diagnostics and trace element quantification in the presence of self-absorption.
• The technique offers a significant improvement for elemental analysis in materials science and industrial applications.