Melting in multilayer adsorbed films

Journal Article · Fri Sep 01 04:00:00 EDT 1989 · Physical Review (Section) B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.40.4938· OSTI ID:5524516

Pettersen, M S; Lysek, M J; Goodstein, D L ^[1]

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1. Condensed Matter Physics 114-36, California Institute of Technology, Pasadena, California 91125 (US)

We present both an improved model and new experimental data concerning the problem of melting in multilayer adsorbed films. The model treats in a mutually consistent manner all interfaces in a stratified film. This results in the prediction of substrate freezing, a phenomenon thermodynamically analogous to surface melting. We also compare the free energies of stratified films to those of homogeneous films. This leads to an orderly classification of multilayer phase diagrams in the vicinity of the bulk triple point. The results of the model are compared with the experimentally known systems. Of these, only methane/graphite exhibits melting from homogeneous solid to homogeneous liquid in multilayer films. The systems Ne/graphite and Ar/graphite, studied by Zhu and Dash, exhibit surface melting and substrate freezing instead. We observe experimentally, by means of pulsed nuclear magnetic resonance, that melting in methane adsorbed on graphite extends below the film thickness at which the latent heat of melting is known to vanish. The multilayer melting curve in this system is a first-order prewetting transition, extending from triple-point dewetting at bulk coexistence down to a critical point where the latent heat vanishes at about four layers, and apparently extending to thinner films as a higher-order, two-dimensional phase transition. It would therefore seem that methane/graphite is an ideal system in which to study the evolution of melting from two dimensions to three dimensions.

• OSTI ID: 5524516
• Journal Information: Physical Review (Section) B: Condensed Matter; (USA), Journal Name: Physical Review (Section) B: Condensed Matter; (USA) Vol. 40:7; ISSN 0163-1829; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
ADSORPTION
ALKANES
ARGON
CARBON
DIAGRAMS
ELEMENTAL MINERALS
ELEMENTS
ENERGY
FLUIDS
FREE ENERGY
GASES
GRAPHITE
HYDROCARBONS
MAGNETIC RESONANCE
MELTING
METHANE
MINERALS
NEON
NONMETALS
NUCLEAR MAGNETIC RESONANCE
ORGANIC COMPOUNDS
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RARE GASES
RESONANCE
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
THERMODYNAMIC PROPERTIES
TRIPLE POINT