The relative alloy sensitivity factor of the Pt-Cu system

Abstract

The variation of the relative alloy sensitivity factor P PtCu used in the quantitative AES analysis of Pt-Cu alloys as a function of the atomic concentration of Pt was measured for in situ scraped sample surfaces. Through different Auger line combinations, i.e. Cu(105)-Pt(237), Cu(920)-Pt(237), and Cu(920)-Pt(1967), three sets of P PtCu were obtained. It was found that the as-measured P PtCu changes with composition in a complex manner. However, after background slope correction in the low energy range and noise correction in the high energy range, the variation of P PtCu of Cu(105)-Pt(237) and Cu(920)-Pt(237) become blurred while P PtCu of Cu(920)-Pt(1967) still decreases approximately 30% if the composition changes from 19 to 90 at% Pt. The variation of P PtCu of Cu(920)-Pt(1967) with composition is in agreement with that P PtCu should in principle not be constant with composition as it contains factors such as backscattering factor and escape depth, which are functions of composition. But the blurring of the variation of P PtCu of Cu(105)-Pt(237) and Cu(920)-Pt(237) with composition contradict this. If these variations also exist, the present results show that they may be too small to be detected with the present method. Though the change of P PtCu itself does not have a serious effect on the quantitative AES analysis, in view of the difficulty in accurate determination of the background slope and the noise corrections, the calibration curve method is suggested for accurate AES analysis, especially in dilute alloys.