AVS 46th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS-WeP

Paper SS-WeP8
Lateral Compression of a Xe Film Physisorbed on the Surface of a Silver Single Crystal

Wednesday, October 27, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: S. Igarashi, Gakushuin University, Japan
Authors: S. Igarashi, Gakushuin University, Japan
A. Tosaka, Gakushuin University, Japan
T. Hirayama, Gakushuin University, Japan
I. Arakawa, Gakushuin University, Japan
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The layering transition of a physisorption system on a metal single crystal has been investigated by means of an ellipsometry and an eXtremely-low-current LEED (XLEED). Our XLEED system is operated at the primary electron current of about 1 pA or less, which minimizes the effect of desorption, defect formation, and charging.@footnote 1@ We observed the surface structure of Xe/Ag(111) by XLEED while monitoring the layer growth by the ellipsometry from a submonolayer film to a thick one. An equilibrium between the Xe film and coexisting three-dimensional Xe gas has been maintained throughout the experiment. From a monolayer film to a sufficiently thick film, the Xe overlayer has clear hexagonal structure whose directions of the unit vectors are coincident with those of the substrate. The Xe-Xe spacing in the monolayer film on Ag(111) is known to be a few per cent larger than that of bulk. Our interest is how the Xe-Xe spacing varies in the process of layer growth. We have made a systematic observation of the change of the Xe-Xe spacing in one and two monolayer films at pressures between 10@super -7@ and 10@super -2@ Pa and at temperatures between 50 and 100 K. In the case of isothermal growth at 78.4 K, for example, the Xe-Xe spacing of the monolayer film is 4.53 Å at immediately after the first layer condensation at 1x10@super -5@ Pa and decreases gradually to 4.5 Å with increasing a surrounding pressure up to 1x10@super -3@ Pa. Then the spacing decreases rapidly and reaches almost that of bulk, 4.39 Å, just before the second layer condensation at the pressure of 4x10@super -2@ Pa. @FootnoteText@ @footnote 1@ S. Igarashi, Y. Abe, Y. Irie, T. Hirayama and I. Arakawa, J. Vac. Sci. Technol. A 16, 974 (1998).