Pulsed CO2 laser-induced gas plasma spectroscopy based on single beam splitting for trace metal analysis on a material surface

摘要

Laser-induced gas plasma spectroscopy based on pulsed CO2 laser beam splitting has been applied to the problem of trace film analysis on the silicon surface. In this study, 2.1J of laser energy (70% of the laser beam) was focused at a 10-degree incidence on a metal mesh attached to a sample surface containing trace metal elements in order to produce a gas plasma. The remaining part of the laser beam (approximately 30% or 0.9J) was employed to vaporize a film which had been deposited on the material by focusing the laser beam 3cm under the surface. In this scheme, the vaporized metal film moves into the gas plasma region, in which the dissociation and excitation takes place. Our measurements show that the detection of Cr on the silicon surface can be made with high sensitivity. The limit of detection of Cr in the silicon material was approximately 7.5x10(12)atom/cm(2).