Statistical thermodynamics of the fluid-solid interface

Journal Article · Thu Jun 13 04:00:00 EDT 1996 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/jp9603288· OSTI ID:374476

Diestler, D J ^[1]

---

1. Univ. of Nebraska, Lincoln, NE (United States)

Although the fluid-fluid interface has been fully described within the framework of classical statistical thermodynamics, a similarly complete treatment of the fluid-solid interface is lacking. Fluid-solid interfacial tension {gamma}{sub f}, which cannot be directly measured, is here defined operationally by a gedanken experiment (analogous to the classic experiment measuring fluid-fluid interfacial tension) in which the fluid is allowed to spread uniformly over the solid surface while the local intensive properties of the two phases are kept fixed. A general statistical-mechanical expression for {gamma}{sub f} is derived, which for the first time accounts for dynamic coupling between molecular motions in the solid and fluid phases. In the limit of decoupling (the molecules in the solid become fixed; the effective temperature of the solid approaches T = 0 K) this expression reduces to a previous formula for the interfacial tension based on a rigid solid (T = 0 K). A new contribution to the interfacial tension in the rigid-solid limit, due to the reaction of the fluid to the `stretching` of the solid, is found. By means of thermodynamic perturbation theory an explicit expression for {gamma}{sub f} is derived from a simple model - a dilute vapor in contact with an Einstein solid - and used to demonstrate the substantial influence on interfacial tension of thermal coupling between the phases. 18 refs., 2 figs.

• DOE Contract Number: FG02-85ER60310
• OSTI ID: 374476
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 24 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
99 GENERAL AND MISCELLANEOUS
COUPLING
FLUIDS
INTERFACES
MATHEMATICAL MODELS
PHYSICAL CHEMISTRY
SOLIDS
STATISTICAL MECHANICS
STATISTICS
SURFACE TENSION
THERMODYNAMICS
VAPORS