AVS 54th International Symposium | |
Surface Science | Tuesday Sessions |
Session SS2-TuA |
Session: | Excitations at Surfaces |
Presenter: | E.T. Jensen, University of Northern British Columbia, Canada |
Correspondent: | Click to Email |
We have studied the transfer of low-energy electrons through thin films of n-hexane (C6H12) on a Cu(110) substrate. The band structure of the thin n-hexane layers allows relatively long-lived image states to be formed at the hexane-vacuum interface.1,2 In our experiments, these image states are occupied by sub-vacuum level photoelectrons from the Cu(110) substrate that are generated by a near-UV laser, and tunnel through the n-hexane film into the image states. These image state electrons can couple to the unoccupied electron affinity levels of coadsorbed CH3X (X=Br, I). Dissociative electron attachment (DEA) of the CH3X is detected by the fission of the C-X bond, with the CH3 fragment escaping into the vacuum and subsequently detected by a quadrupole mass spectrometer. The intermediary role of the image states in this DEA process is determined from the coverage dependencies of the CH3 fragment yields and the distinctive translational energy distribution of the CH3- the image state electrons constitute a nearly monochromatic electron source for DEA of the CH3X.
1M.W. Cole, Phys. Rev. B 3 (1971) 4418.
2K. Nagesha and L. Sanche, Phys. Rev. Lett. 81 (1998) 5892.