Simple method of depth profiling (stratifying) contamination layers, illustrated by studies on stainless steel

• Published in: Surface and interface analysis 1994-06, Vol.21 (6-7), p.336-341
• Main Authors: Seah, M. P., Qiu, J. H., Cumpson, P. J., Castle, J. E.
• Format: Article
• Language: English
• Subjects: Analysing. Testing. Standards; Analytical chemistry; Applied sciences; Chemistry; Exact sciences and technology; Measurement of surface state; Metals. Metallurgy; Nondestructive testing; Spectrometric and optical methods
• ISSN: 0142-2421; 1096-9918
• DOI: 10.1002/sia.740210603

Stainless‐steel artefacts are used as reference masses for the calibration of balances and instruments involving force. The surfaces of these masses react with the environment, leading to changes in the chemistry of the steel surface, accretion of surface contamination layers and a dynamic absorption of moisture in those contamination layers. In order to understand these layers, to stabilize or correct for the concomitant mass changes, it is important to define what chemical states are developing and their stratification at the surface. Four chemical states are identified in the oxygen XPS peak and four in the carbon peak. In the project a very large number of samples are studied and so a rapid, simple stratifying method has been developed requiring measurements at only two angles of emission. The method, which involves a simple ratio of the peak intensities either after separation of the states or by using the peak envelope, or just by ratioing the whole spectra at the two angles enables the stratification and other parameters to be readily determined for all eight peaks.