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Phases and Phase Transitions in the First Few Layers of Methane, Argon and Krypton Adsorbed on Graphite

Goodstein, David and Day, P. and LaMadrid, M. and Lysek, M. (1992) Phases and Phase Transitions in the First Few Layers of Methane, Argon and Krypton Adsorbed on Graphite. In: Evolution of Surface and Thin Film Microstructure. MRS Proceedings. No.280. Materials Research Society , Pittsburgh, MA, pp. 319-326. ISBN 9781107409590. https://resolver.caltech.edu/CaltechAUTHORS:20151217-082051420

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Abstract

The equilibrium phase diagrams of monolayers of many substances adsorbed on graphite have long been studied as examples of 2-dimensional (2D) matter. One typically observes 2D gas and liquid phases, and solid phases that may be commensurate or incommensurate with the substrate lattice. Many experimental techniques have been used, but thermodynamic measurements are generally the most useful for tracing out phase boundaries. Recent advances in technique have made it possible to use thermodynamic measurements to study the phase diagrams of the second and higher layers, up to the fifth or sixth. These advances include ultra high resolution scanning calorimetry, and a detailed understanding of the role of capillary condensation in corners and pores of the graphite foam substrate. We find a rich array of phases and phase transitions in multilayer methane, argon and krypton. The second and third layers typically have distinct 2D gas, liquid and solid phases evidenced by 2D triple points and critical points. We observe phase transitions between solid phases that are commensurate and incommensurate with the layer below. We also observe melting of the first layer at higher temperatures, even when one to five additional layers are adsorbed on top of it. In argon and krypton, but not in methane, a strange new phenomenon is observed at temperatures above the gas-liquid critical point of the nth layer for n> 3. Below that temperature, nthlayer gas coexists with a condensed nth layer. At some temperature above it, a new coexistence region is observed in which a partial nth layer coexists with a partial n + 1st layer. This behavior is thought to be evidence for a theoretically predicted phase transition of the bulk interface, called the preroughening transition.


Item Type:Book Section
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1557/PROC-280-319DOIArticle
Additional Information:© 1992 Cambridge University Press. This work was supported by DOE grant# DE-FG03-85ER45192.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG03-85ER45192
Series Name:MRS Proceedings
Issue or Number:280
DOI:10.1557/PROC-280-319
Record Number:CaltechAUTHORS:20151217-082051420
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20151217-082051420
Official Citation: David Goodstein, P. Day, M. LaMadrid and M. Lysek (1992). Phases and Phase Transitions in the First Few Layers of Methane, Argon and Krypton Adsorbed on Graphite. MRS Proceedings, 280, 319 doi:10.1557/PROC-280-319.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63023
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:17 Dec 2015 18:11
Last Modified:10 Nov 2021 23:10

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