Catalysis sampling depths

XPS is among the most frequently used techniques in catalysis. It yields information on the elemental composition, the oxidation state of the elements and in favorable cases on the dispersion of one phase over another. When working with flat layered samples, depth-selective information is obtained by varying the angle between sample surface and the analyzer. Several excellent books on XPS are available [5,8,17-20], In this section we first describe briefly the theory behind XPS, then the instrumentation, and finally we illustrate the type of information that XPS offers about catalysts and model systems. 

Strength (FLS) empirical approach are discussed in Section 3 as methods for determining the molecular structures of metal-oxide species from their Raman spectra. The state-of-the-art in Raman instrumentation as well as new instrumental developments are discussed in Section 4. Sampling techniques typically employed in Raman spectroscopy experiments, ambient as well as in situ, are reviewed in Section S. The application of Raman spectroscopy to problems in heterogeneous catalysis (bulk mixed-oxide catalysts, supported metal-oxide catalysts, zeolites, and chemisorption studies) is discussed in depth in Section 6 by selecting a few recent examples from the literature. The future potential of Raman spectroscopy in heterogeneous catalysis is discussed in the fmal section. 

---