Photoemission spectra with synchrotron

The measurements by Murgai et al. (1982) were performed with synchrotron radiation using a photon energy of 120 eV. This leads to a considerable surface sensitivity of the measurements with an information depth of only a few atomic layers. In the present systems this photon energy has also the particular advantage that it is close to the Cooper minimum for the Pd 4d emission. This means that in the photoemission spectrum there is an almost total dominance of the Eu 4f states in the valence band energy region. 

An average valence of v = 2.83 is derived for nearly stoichiometric TmSe from the lattice constant and v = 2.62 from the effective magnetic moment, Kobler et al. [16]. The value v = 2.62 is also deduced from the X-ray Lm absorption spectrum by Bianconi etal. [5, 17, 18], and v = 2.6 0.08 from bremsstrahlung isochromat spectroscopy (BIS) by Oh, Allen [19]. A value of v = 2.62 0.15 is obtained for the same crystal (Tm osSe, a = 5.715 A) by resonant-photoemission spectroscopy with use of synchrotron radiation in the soft X-ray region (70 to 200 eV) and constant-final-state technique (CFS), Oh et al. [41]. The valence v = 2.77 is obtained from the lattice constant and 2.46 or 2.58 from magnetic data between 77 and 300 K or 400 and 800 K, respectively, Holtzberg et al. [20]. These values are nearly confirmed for TmSe with a = 5.713 A... 

Another example of the interaction of water with a relatively simple metal oxide surface is provided by the water vapor/a-Al203(0001) system (Figure 7.9(a)). Oxygen Is synchrotron radiation photoemission results indicate that significant dissociative chemisorption of water molecules does not occur below 1 torr p(H20) [149]. However, following exposure of the alumina (0001) surface to water vapor above this threshold p(H20) , a low kinetic energy feature in the Is spectrum grows quickly,... 

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