COLL 264 |
| Staffan Westerberg, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720 and G. A Somorjai, Department of Chemistry and Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720. |
| Vibrational frequencies for NH and NH2 have been identified on the clean and pre-oxidized Fe(111). Ammonia molecules have been found to dissociate at room temperature on both clean and pre-oxidized Fe(111) under high pressure of ammonia (20 - 600 Torr). Introduction of 0.5 Torr of oxygen does not change the vibrational frequencies of NH and NH2. However, the spectral features were reversed due to a change of phase between the resonant and the non-resonant second order non-linear susceptibility. Heating the surface in presence of high pressure ammonia reduced the oxygen coverage and another relative phase change restored the spectral features. A large SFG non-resonant signal was observed on the clean Fe(111). Adsorption of gases N2, H2, O2 and NH3 on Fe(111) caused a distinct change in signal intensity. The change in SFG non-resonant signal could be used to follow surface reactions. |
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Vibrational Analyses of Dry and Wet Surfaces
6:00 PM-8:00 PM, Monday, March 29, 2004 Disneyland -- North Exhibit Hall, Poster
Division of Colloid and Surface Chemistry |