Search for evidence of commensurate argon-on-graphite films near monolayer completion

Journal Article · Mon Sep 01 04:00:00 EDT 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.56.6462· OSTI ID:542616

Johnson, D E ^[1]; Phillips, J M ^[2]; Larese, J Z ^[1]

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1. Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)
2. Department of Physics, University of Missouri-Kansas City, Kansas City, Missouri 64110 (United States)

The structural properties of argon films adsorbed on graphite at 85 K were investigated as a function of coverage using neutron diffraction. This study was prompted by the recent high-resolution heat-capacity measurements of Day {ital et al.} which uncovered a series of anomalies near monolayer melting. These features were attributed to the formation of a registered, {radical}(3){times}{radical}(3) R30{degree} phase. The diffraction study presented here shows that this commensurate phase does not exist in the portion of the phase diagram suggested by the thermodynamic study. On the contrary, a compressed solid phase with a lattice constant close to that of the close-packed plane of the bulk solid forms. Evidence of second-layer population in the diffraction study suggests that these heat-capacity anomalies might be direct evidence of layer promotion. {copyright} {ital 1997} {ital The American Physical Society}

• Research Organization: Brookhaven National Laboratory
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 542616
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 11 Vol. 56; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
ADSORPTION
ARGON
GRAPHITE
NEUTRON DIFFRACTION
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
SPECIFIC HEAT
SURFACES
TEMPERATURE RANGE 0065-0273 K