ISSN:
1089-7690
Quelle:
AIP Digital Archive
Thema:
Physik
,
Chemie und Pharmazie
Notizen:
We investigate the effects of the geometrical structure (phase and porosity) of multilayer benzene films on the desorption of O− induced by 2–20 eV electron impact on varying quantities of absorbed O2. Differences in the yield of O− from O2 doped amorphous and crystalline benzene films are attributed to the ability of O2 to diffuse into the amorphous solid via pores and defects formed during its deposition at 20 K. In contrast, diffusion into crystalline benzene is limited and deposited O2 molecules remain at the surface of the film. Thermal desorption measurements support this analysis. The data are also compared with results of similar experiments for O2 on water. While it is apparent that some of the variation in O− yield observed from ice films is similarly related to morphology, a substantial suppression of the O− yield is likely to result from energy loss by electrons prior to dissociation. Quenching of intermediate O2− states by water ice may also contribute to this suppression in the range 5–12 eV. © 2001 American Institute of Physics.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.1394733
