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Structure of Kcn Monolayer Films Vapor-Deposited onto Cleaved KBr(001) by Helium Atom Diffraction

Published online by Cambridge University Press:  15 February 2011

S. A. Safron
Affiliation:
Department of Chemistry and MARTECH, Florida State University, Tallahassee, FL 32306-3006, safron@chem.fsu.edu
J. R. Baker
Affiliation:
current address, National Research Laboratory, Risø, Denmark, jeff.baker@risoe.dk
J. A. Lit
Affiliation:
Department of Physics and MARTECH, Florida State University, Tallahassee, FL 32306-3016, jaime@scri.fsu.edu, elshan@surf0.martech.fsu.edu, tom@surf0.martech.fsu.edu, skofronick@phy.fsu.edu.
E. A. Akhadov
Affiliation:
Department of Physics and MARTECH, Florida State University, Tallahassee, FL 32306-3016, jaime@scri.fsu.edu, elshan@surf0.martech.fsu.edu, tom@surf0.martech.fsu.edu, skofronick@phy.fsu.edu.
T. W. Trelenberg
Affiliation:
Department of Physics and MARTECH, Florida State University, Tallahassee, FL 32306-3016, jaime@scri.fsu.edu, elshan@surf0.martech.fsu.edu, tom@surf0.martech.fsu.edu, skofronick@phy.fsu.edu.
J. G. Skofronick
Affiliation:
Department of Physics and MARTECH, Florida State University, Tallahassee, FL 32306-3016, jaime@scri.fsu.edu, elshan@surf0.martech.fsu.edu, tom@surf0.martech.fsu.edu, skofronick@phy.fsu.edu.
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Abstract

Angular distribution measurements of the helium atom scattering intensity from monolayer films of KCN/KBr(001) for several azimuths over a temperature range of approximately 40–200 K reveal that above ˜95 K the KCN monolayer forms a (1×1) overlayer structure with respect to the KBr substrate. (The lattice spacing of bulk KCN in the rocksalt-structure phase differs from that of KBr by only ˜ 1%.) Below this temperature the overlayer appears to be (2×1), and “missing” diffraction spots in the <110> high symmetry direction suggest the existence of a glide plane. The inferred structure for this low temperature phase consists of K+ ions fixed in their rocksaltstructure positions relative to the substrate and the CN ions oriented so that their dipoles are aligned antiferroelectrically within the new unit cell.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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