HEAT-CAPACITY OF MULTILAYER METHANE ON GRAPHITE - PHASE-TRANSITIONS IN THE 1ST 4 LAYERS

被引:18
作者
LYSEK, MJ
LAMADRID, MA
DAY, PK
GOODSTEIN, DL
机构
[1] Condensed Matter Physics 114-36, California Institute of Technology, Pasadena
来源
PHYSICAL REVIEW B | 1993年 / 47卷 / 12期
关键词
D O I
10.1103/PhysRevB.47.7389
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
We present high-resolution heat-capacity data for methane adsorbed on graphite for nominal coverages of 0.87 to 7 layers, from T = 70 to 120 K. For films thicker than 1.1 layers, we find capillary condensate coexisting with the film. We have performed heat-capacity scans on films formed by both adsorption and desorption. By comparing the locations of the phase transitions in the chemical potential mu vs T plane, we find that there is no significant interaction between the film and the capillary condensate. The heat-capacity signals from the films map out an unexpectedly rich set of phenomena for the second, third, and fourth layers, including a two-dimensional triple point and a liquid-gas coexistence region for each layer. The fourth-layer critical temperature we find is lower than previous values found by vapor-pressure isotherms.
引用
收藏
页码:7389 / 7400
页数:12
相关论文
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