AVS 49th International Symposium
    Surface Science Thursday Sessions
       Session SS-ThM

Paper SS-ThM9
Ultraviolet Laser Interactions with Single Crystal Sodium Nitrate: Wavelength Dependence of Photodesorbed Products

Thursday, November 7, 2002, 11:00 am, Room C-108

Session: Electronic Structure and Stimulated Processes
Presenter: L. Cramer, Washington State University
Authors: L. Cramer, Washington State University
J.T. Dickinson, Washington State University
W.P. Hess, Pacific Northwest National Laboratory
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Sodium nitrate is a wide bandgap ionic material containing an oxyanion. Single crystals show a strong absorption band in the ultraviolet due to a @pi@ to @pi@* transition in the nitrate. Previous work has suggested that a number of neutral emission products are due to direct excitation of this band. In this study we compare the laser induced ion and neutral atom/molecule emissions from single crystal NaNO@sub 3@ at three wavelengths: at the band maximum (193 nm) and two minima on either side of the maximum (248 nm and 157 nm). Surprisingly, little correlation with the @pi@ to @pi@* absorption is observed, including molecular species derived from the nitrate. Our results are better explained by defect mediated processes attributed to anion vacancies. These results are corroborated by simultaneous laser induced photoelectron emission measurements that are very sensitive to low densities of electron trap defects at insulating surfaces.