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Abstract:
A cylindrically-shaped Ge crystal with the orientations (001), (113), (111), (110) and all intermediates between them on its surface was used to study the adsorption of NO by Auger and photoelectron spectroscopy applying laboratory sources (He I, Mg Ka) and synchrotron radiation. A strong orientation dependence of the adsorbed amount is observed. Between 60 K and 130 K, coadsorption of NO and O with a maximum at (001) is observed. No or only very little atomic N is found. Upon warming up to above 200 K, NO desorbs and only atomic O remains. Exposure at 300 K, however, yields fully dissociative adsorption of both atomic N and O. The orientation dependence of this reaction indicates a strong influence of atomic steps. The atomic N is quite tightly bound and desorps thermally at higher temperatures than oxygen.
