Improvement of Analysis Precision of Laser Microprobe Analyser by Correcting Self-Absorption

Abstract

The slope of the calibration curve obtained in laser microprobe analysis (LMA) is usually small compared with that obtained in con ventional spectrochemical analysis, resulting in poor sensitivity and poor precision. The main cause for the small slope of the calibra tion curve has been referred to self-absorption of the spectral line. Efforts have therefore been made to reduce the effect of self-absorp tion by selecting the proper analytical condi tion 1). In this paper, a calculation procedure for correcting self-absorption is proposed and improvement of the slope of the calibration curve is reported. The experiment was carried out using a normal laser microprobe with auxiliary spark excitation. Figure 1 shows the arrangement of spark electrodes and the sample. Spectra of copper in aluminium samples were recorded on a photographic plate. Fig. 1. Schematic diagram showing the arrange ment of auxiliary spark electrodes and the sample.