Hydrogen inelastic energy loss

The most recent results for hydrogen chemisorbed on Raney nickel by Kelly et aj[ (30) are shown in Fig. 8. The inelastic neutron TOF spectra are taken at 77 K in the energy-loss mode with the background spectrum of the reduced Raney Ni sample after desorption of adsorbed species (Fig. 8(a)) subtracted. Figure 8(b) is the pectrum for a hydrogen monolayer. Features at -120 meV (960 cm-i)and -140 meV (1120 cm-1)are in excellent agreement with previous results of Renouprez et al (28,29). In addition, a peak at 78 meV (624 cm"1) is clearly resolved. 

Adsorbed hydrogen on metal surfaces is of particular interest from both theoretical and experimental points of view. Vibrational spectroscopy data on hydrogen adsorbed from the gas phase have been obtained from IR reflection-absorption experiments as well as from electron energy loss spectroscopy and inelastic neutron scattering techniques [39-41]. In UHV, absorption bands for the M-H bond have been reported in the mid- and far-infrared regions [41, 42],... 

The model system comprising the reaction sequence from initial 0-atom attack to steady-state erosion of a hydrocarbon surface can serve as a benchmark for fundamental atom-surface interactions at hyperthermal collision energies and for etching mechanisms of materials. Within this model system, there is still much to learn. It is likely that when a hyperthermal oxygen atom strikes a saturated hydrocarbon surface, it will either abstract a hydrogen atom or it will scatter inelastically. The subsequent reaction sequence becomes murky. Very little is known about the mechanisms of oxidation, surface roughening, or material loss. In fact, even the sticking... 

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