No abstract

No abstract

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Using metal and metal oxide surfaces as examples, three aspects of quantitative X-ray photoelectron spectoscopy are discussed, namely, the effects of surface contamination and structure, dilution effects in mixtures, and the influences of stoichiometry on photoelectron intensity ratios. The intensity attenuating effect of carbon was determined for several types of surfaces, and, in all cases, a quasi-linear relationship was found between the intensities of carbon and those of the specimen matrix. The slope of the line is dependent upon the surface structure of the matrix as well as well as the kinetic energy of the matrix photoelectron. Excess oxygen in an oxide matrix has little effect on the metal and oxide line intensities, but heavy metal impurities incorporated into the surface strongly attenuate the matrix lines. The metal line intensities from copper-nickel and iron-nickel alloys were determined as a function of composition. The intensity of each component varied linearly with the atomic fraction indicating that the electron scattering cross section is not significantly different in these metals or their alloys. Quantitative measurement of these surfaces is practical only when the more deeply probing M(3p) electon lines are used. Oxygen/metal photoelectron intensity ratios are a reproducible property of a particular oxide. Their ratios, however, are altered not only by changes in stoichiometry, but to some extent by changes in structure. Quantitative analysis of an oxide surface is thus reliable only for specimens where the oxide structure is identical to the standard throughout the compositional range of interest.