レーザー発光分光分析における試料表面の汚れ

抄録

In laser microspectral analysis using cross-excitation by an auxiliary spark discharge, a stain produced around a crater was presumed to be due to deposit of carbon from the electrodes and oxidation of the sample surface heated by the spark plasma.The form and degree of the stain vary with the spark discharge condition.That is, the forms were coincident with those of spark plasma observed under various conditions, and in case a flat spark plasma was used, both amounts of carbon and oxygen were less than those produced when a spherical spark plasma was employed.
In order to prevent the sample surface from being stained, it was desirable to select the discharge condition so as to produce the flat spark plasma and moreover to increase the distance between the sample and the electrode points.In case it was desired to analyse the thin surface layer only, a good result was obtained by displacing the focus of the laser beam upward by several hundreds microns from the sample surface and by selecting the spark discharge condition to produce the flat spark plasma.