| AVS 55th International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS-TuM |
| Session: | Dynamics at Surfaces |
| Presenter: | S.K. Kim, Seoul National University, South Korea |
| Authors: | S. Ryu, Seoul National University, South Korea H. Kwon, Seoul National University, South Korea J. Chang, Seoul National University, South Korea J. Park, Seoul National University, South Korea S.K. Kim, Seoul National University, South Korea |
| Correspondent: | Click to Email |
Solvation and transfer dynamics of photo-injected electrons in thin ice film of water or ammonia co-adsorbed with a CFC (chlorofluorocarbon) molecule such as CFCl3 on Ag(111) have been investigated by time-resolved two-photon photoemission spectroscopy. Water molecules were found to solvate the photo-injected electron within the first several hundreds of fs. The significant lifetime decrease upon adsorption of CFC on the ice film was attributed to dissociative electron transfer of the solvated electrons, based on the observed scission of C–Cl bonds. Furthermore, the photodissociation rate of CFC adsorbed directly on Ag(111) was observed to increase drastically owing to the transfer of the solvated electron when an ice film was overlaid. In the case of ammonia ice film, we found that the lifetime of the solvated electron was much shorter than in water ice. The solvated electron state was found to be located at 2.4 eV above the Fermi level with a binding energy of 0.7 eV at 1 ML of ammonia, and its peak intensity decreased drastically upon increasing the coverage. To shed more light on the excitation process, polarization dependence of the solvated electron peak was thoroughly investigated while modulating the coupling between ammonia and the substrate by use of n-octane as a spacer layer. The observed dynamics of solvation and transfer of electron and the ice layer-induced enhancement of the photoreaction demonstrate the active role of water or ammonia as an electron solvent, which should have far-reaching implications for many electron-driven chemical reactions, including, for example, the newly proposed dissociation mechanism of chlorofluorocarbons by quasi-free or loosely bound electrons on the polar stratospheric clouds.