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Title: Synchrotron x-ray-diffraction study of the structure and growth of Xe films adsorbed on the Ag(111) surface

Abstract

Synchrotron x-ray scattering has been used to investigate the structure and growth of perhaps the simplest of all films: xenon physisorbed on the Ag(111) surface. High-resolution x-ray scans of the in-plane structure and lower-resolution scans (specular and nonspecular) of the out-of-plane order were performed. The Xe films were prepared under both quasiequilibrium and kinetic growth conditions, and have fewer structural defects than those investigated previously by others on graphite substrates. Under quasiequilibrium conditions, the bulk Xe-Xe spacing is reached at monolayer completion, and the monolayer and bilayer lattice constants at coexistence are inferred equal to within 0.005 {Angstrom}, consistent with theoretical calculations. The Xe/vacuum interface profile for a complete monolayer and bilayer grown at quasiequilibrium is found to be sharper than for kinetically grown films. At coverages above two layers, diffraction scans along the Xe(01l) rod for quasiequilibrated films are consistent with the presence of two domains having predominantly an {ital ABC} stacking sequence and rotated 60{degree} with respect to each other about the surface normal. Annealing of these films alters neither the population of the two domains nor the fraction of {ital ABA} stacking faults. The thickest film grown under quasiequilibrium conditions exceeds 220 {Angstrom} (resolution limited). Under kineticmore » growth conditions, x-ray intensity oscillations at the Xe anti-Bragg position of the specular rod are observed as a function of time, indicating nearly layer-by-layer growth. Up to four complete oscillations corresponding to a film of eight layers have been observed before the intensity is damped out; the number of oscillations is found to depend on the substrate temperature, the growth rate, and the quality of the Ag(111) substrate. The specular reflectivity from kinetically grown films at nominal coverages of three and four layers has been analyzed using a Gaussian model which gives a film thickness standard deviation of 0.5 and 1.0 layers, respectively. Diffraction scans along the Xe(01l) rod of these films indicate a larger fraction of {ital ABA} stacking faults than found for thicker films. These results demonstrate the difficulty of kinetically growing Xe films thicker than two layers which have an ideal slab geometry. {copyright} {ital 1999} {ital The American Physical Society}« less

Authors:
; ; ; ;  [1];  [2]
  1. Department of Physics and Astronomy, University of Missouri--Columbia, Columbia, Missouri 65211 (United States)
  2. School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)
Publication Date:
OSTI Identifier:
345434
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter
Additional Journal Information:
Journal Volume: 59; Journal Issue: 23; Other Information: PBD: Jun 1999
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; 66 PHYSICS; REFLECTIVITY; XENON; SILVER; ADSORPTION; X-RAY DIFFRACTION; SYNCHROTRON RADIATION; THIN FILMS; LATTICE PARAMETERS; ANNEALING; STRUCTURAL CHEMICAL ANALYSIS; STACKING FAULTS

Citation Formats

Dai, P, Wu, Z, Angot, T, Wang, S, Taub, H, and Ehrlich, S N. Synchrotron x-ray-diffraction study of the structure and growth of Xe films adsorbed on the Ag(111) surface. United States: N. p., 1999. Web. doi:10.1103/PhysRevB.59.15464.
Dai, P, Wu, Z, Angot, T, Wang, S, Taub, H, & Ehrlich, S N. Synchrotron x-ray-diffraction study of the structure and growth of Xe films adsorbed on the Ag(111) surface. United States. doi:10.1103/PhysRevB.59.15464.
Dai, P, Wu, Z, Angot, T, Wang, S, Taub, H, and Ehrlich, S N. Tue . "Synchrotron x-ray-diffraction study of the structure and growth of Xe films adsorbed on the Ag(111) surface". United States. doi:10.1103/PhysRevB.59.15464.
@article{osti_345434,
title = {Synchrotron x-ray-diffraction study of the structure and growth of Xe films adsorbed on the Ag(111) surface},
author = {Dai, P and Wu, Z and Angot, T and Wang, S and Taub, H and Ehrlich, S N},
abstractNote = {Synchrotron x-ray scattering has been used to investigate the structure and growth of perhaps the simplest of all films: xenon physisorbed on the Ag(111) surface. High-resolution x-ray scans of the in-plane structure and lower-resolution scans (specular and nonspecular) of the out-of-plane order were performed. The Xe films were prepared under both quasiequilibrium and kinetic growth conditions, and have fewer structural defects than those investigated previously by others on graphite substrates. Under quasiequilibrium conditions, the bulk Xe-Xe spacing is reached at monolayer completion, and the monolayer and bilayer lattice constants at coexistence are inferred equal to within 0.005 {Angstrom}, consistent with theoretical calculations. The Xe/vacuum interface profile for a complete monolayer and bilayer grown at quasiequilibrium is found to be sharper than for kinetically grown films. At coverages above two layers, diffraction scans along the Xe(01l) rod for quasiequilibrated films are consistent with the presence of two domains having predominantly an {ital ABC} stacking sequence and rotated 60{degree} with respect to each other about the surface normal. Annealing of these films alters neither the population of the two domains nor the fraction of {ital ABA} stacking faults. The thickest film grown under quasiequilibrium conditions exceeds 220 {Angstrom} (resolution limited). Under kinetic growth conditions, x-ray intensity oscillations at the Xe anti-Bragg position of the specular rod are observed as a function of time, indicating nearly layer-by-layer growth. Up to four complete oscillations corresponding to a film of eight layers have been observed before the intensity is damped out; the number of oscillations is found to depend on the substrate temperature, the growth rate, and the quality of the Ag(111) substrate. The specular reflectivity from kinetically grown films at nominal coverages of three and four layers has been analyzed using a Gaussian model which gives a film thickness standard deviation of 0.5 and 1.0 layers, respectively. Diffraction scans along the Xe(01l) rod of these films indicate a larger fraction of {ital ABA} stacking faults than found for thicker films. These results demonstrate the difficulty of kinetically growing Xe films thicker than two layers which have an ideal slab geometry. {copyright} {ital 1999} {ital The American Physical Society}},
doi = {10.1103/PhysRevB.59.15464},
journal = {Physical Review, B: Condensed Matter},
number = 23,
volume = 59,
place = {United States},
year = {1999},
month = {6}
}