[Study on the quality of spectral line of laser microprobe emission spectral analysis]

In this paper, the quality improvement of Laser Microprobe Emission Spectral Analysis (LMESA) lines in argon atmosphere at reduced pressure was experimentally investigated. The experimental setup consists of a YGJ-II laser micro-spectral analyzer and a photo-electro detection system. The temporal behavior and the intensity distribution of Cu I 324.7 nm and Cu I 327.4 nm lines of the copper alloy standard samples were studied. The results show that LMESA spectrum strongly depends on the environment gas, its pressure and the auxiliary excitation parameters. When the diameter at the end of graphite auxiliary electrodes is 1.5 mm, the distance between the electrodes is 4 mm, the center of the electrodes is 3 mm above the sample surface, the voltage of the auxiliary excitation is 1,300 V and the argon pressure is 33.2 Kpa, the emission time of Cu I 324.7 nm and Cu I 327.4 nm is about 500 microseconds longer than that in the air. The emission intensity of Cu I 324.7 nm and Cu I 327.4 nm is about 4 times higher than that in the air at the same pressure and is about 2 times higher than that in the air at normal pressure. The full width at half maximum of the spectral lines is obviously narrowed.