Web Release Date: September 20,
Laser Control of Desorption through Selective Surface Excitation
Pacific Northwest National Laboratory, P. O. Box 999, Richland, Washington 99352
Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
Received: May 6, 2005
In Final Form: June 27, 2005
This paper contains enhanced objects
available on the Internet at http://pubs.acs.org.
Abstract:
We review recent developments in controlling photoinduced desorption processes of alkali halides. We focus primarily on hyperthermal desorption of halogen atoms and show that the yield, electronic state, and velocity distributions of desorbed atoms can be selected using tunable laser excitation. We demonstrate that the observed control is due to preferential excitation of surface excitons. This approach takes advantage of energetic differences between surface and bulk exciton states and probes the surface exciton directly. We demonstrate that desorption of these materials leads to controlled modification of their surface geometric and electronic structures. We then extend the exciton mechanism of desorption, developed for alkali halides, to metal oxide surfaces, in particular magnesium oxide. In addition, these results demonstrate that laser desorption can serve as a solid-state source of halogen and oxygen atoms, in well-defined electronic and velocity states, for studying chemical processes in the gas phase and at surfaces.
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