Modified procedure of quantitative analysis by AES

Abstract

AbstractMuch controversy in the literature is associated with the definitons of terms describing electron transport in solids, i.e. the inelastic mean free path, the attenuation length, the escape depth, etc. This may cause some confusion in determining the corresponding correcting factors for calculations of quantitative AES. There are indications that the proper parameter for the correcting procedure is the inelastic mean free path (IMFP). None the less, difficulties may be encountered in estimating the values of the IMFP for studied samples, particularly for binary or multicomponent systems.A novel procedure of quantitative analysis is proposed in which knowledge of the IMFP is no longer necessary. Actually, the correction procedure normally used requires the ratio of the IMFP for the sample and the standard. One can take advantage of the fact that the IMFP is related to the absolute elastic peak intensity. In that case, determination of the ratio of elastic peak intensities for the sample and the standard makes possible calculation of the ratio of the IMFP. Inasmuch as the measurements of the absolute elastic peak intensities offer considerable experimental difficulties, the determination of the ratio of intensities is relatively easy to perform. Thus, recording the ratio of elastic peak intensities, in addition to the ratio of Auger electron intensities, provides complete information for the correction procedure of quantitative analysis. Such a procedure has two important advantages: the ratio of the IMFP is determined for the studied samples instead of taking these values from the literature, and the actual concentration dependence of the IMFP is accounted for. The calibration plots facilitate recalculation of the ratio of elastic peak intensities to the ratio of the IMFP. Somewhat lengthy calculations are necessary to determine such a plot; however, they are made only once for a given alloy. Application of the proposed method of quantitative analysis is illustrated by using the AuPd alloys.