High-resolution study of the influence of gas adsorption on LEED fine structures
- 1 April 1983
- journal article
- Published by American Vacuum Society in Journal of Vacuum Science & Technology A
- Vol. 1 (2) , 1174-1177
- https://doi.org/10.1116/1.571891
Abstract
Fine structures in LEED I–V curves at low energy (≲20 eV) result from the interference between a wave directly diffracted from the crystal and a wave temporarily trapped in a preemergent beam between the substrate and its surface potential barrier. High-resolution study of these singularities is of great interest since a detailed analysis of their line shape leads to the characterization of the surface barrier of metals. Using a high-resolution electron spectrometer, the intensity of the (00) beam from W(110) in the [10] azimuth is measured revealing a LEED fine structure related to the (2̄0) beam threshold. The effect on this feature of hydrogen and oxygen chemisorption is examined. An enhancement of the singularities and a modification of their line shape is observed with increasing hydrogen coverage while oxygen slightly alters the fine structure up to a coverage of half a monolayer. An analysis based on the four-beam approximation shows that these behaviors reflect a change in the bulk scattering properties caused by the adlayer rather than an important change of the surface barrier. The possibility of relating this kind of observation to the structure of the adlayer is discussed.Keywords
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