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A search for the prewetting lineThis paper describes efforts to locate the prewetting line in a binary liquid system (isopropanol-perfluoromethylcyclohexane) at the vapor-liquid interface. Tight upper bounds were placed on the temperature separation (0.2 K) between the prewetting line and the line of bulk liquid phase separation. The prewetting line in systems at equilibrium was not detected. Experimental signatures indicative of the prewetting line occurred only in nonequilibrium situations. Several theories predict that the adsorption of one of the components (the fluorocarbon, in this case) at the liquid-vapor interface should increase abruptly, at a temperature sightly above the temperature at which the mixture separates into two liquid phases. A regular solution calculation indicates that this prewetting line should have been easily detectable with the instruments used in this experiment. Significant features of the experiment are: (1) low-gradient thermostatting, (2) in situ stirring, (3) precision ellipsometry from the vapor-liquid interface, (4) high resolution differential index of refraction measurements using a novel cell design, and (5) computer control.
Document ID
19860049534
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Schmidt, J. W.
(National Bureau of Standards Gaithersburg, MD, United States)
Moldover, M. R.
(NBS, Thermophysics Div., Gaithersburg MD, United States)
Date Acquired
August 12, 2013
Publication Date
April 15, 1986
Publication Information
Publication: Journal of Chemical Physics
Volume: 84
ISSN: 0021-9606
Subject Category
Inorganic And Physical Chemistry
Accession Number
86A34272
Funding Number(s)
CONTRACT_GRANT: NASA ORDER H-27954-B
Distribution Limits
Public
Copyright
Other

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