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O: Oberflächenphysik

O 11: Poster (I)

O 11.68: Poster

Monday, March 23, 1998, 19:30–22:30, Bereich C

On the abstractive oxidation of Cesium — •Marcello Binetti and Eckart Hasselbrink — Fysisk Institut Odense Universitet Campusvej 55 DK-5230 Odense M DENMARK

In most cases dissociative adsorption of molecules ends with all fragments adsorbed on the surface and the excess energy dissipated in the heat bath of the solid (adiabatic reaction). Nevertheless, in the interaction between electronegative molecules and metal surfaces the existence of abstraction reactions has already been theorethically(1) and experimentally(2) demonstrated. In the case of alkali oxidation, such may be ascribed to non adiabatic reaction channels. For Cesium oxidation, the emission of neutral oxygen atoms that is supposed to accompany the measured negative ions’ one(3) has not yet, to the best of our knowledge, been demonstrated. The attempt to detect these neutral fragments with Resonantly Enhanced Multi Photon Ionization (REMPI) technique and to study the dependence of the O-/O ratio on the impinging molecule translational energy is reported 1)B. Kasemo et al., Surf.Sci. 89 (1979) 554. 2)Böttcher et al., Phys.Rev.Lett. 65 (1990) 2035. 3)Greberet al., Phys.Rev.Lett. 70 (1993) 1331.