Thermodynamic and kinetic supercooling of liquid in a wedge pore
Artikel i vetenskaplig tidskrift, 2008

Cyclohexane allowed to capillary condense from vapor in an annular wedge pore of mica in a surface force apparatus (SFA) remains liquid down to at least 14 K below the bulk melting-point T(m). This is an example of supercooling of a liquid due to confinement, like melting-point depression in porous media. In the wedge pore, however, the supercooled liquid is in equilibrium with vapor, and the amount of liquid (and thereby the radius of curvature r of the liquid-vapor interface) depends on the surface tension gamma(LV) of the liquid, not the interfacial tension between the solid and liquid. At coexistence r is inversely proportional to the temperature depression Delta T below T(m), in accordance with a recently proposed model [P. Barber, T. Asakawa, and H. K. Christenson, J. Phys. Chem. C 111, 2141 (2007)]. We have now extended this model to include effects due to the temperature dependence of both the surface tension and the enthalpy of melting. The predictions of the improved model have been quantitatively verified in experiments using both a Mark IV SFA and an extended surface force apparatus (eSFA). The three-layer interferometer formed by the two opposing, backsilvered mica surfaces in a SFA was analyzed by conventional means (Mark IV) and by fast spectral correlation of up to 40 fringes (eSFA). We discuss the absence of freezing in the outermost region of the wedge pore down to 14 K below T(m) and attribute it to nonequilibrium (kinetic) supercooling, whereas the inner region of the condensate is thermodynamically supercooled.

surface forces apparatus

temperature

cut mica sheets

porous solids

solvation forces

capillary condensation

vapor-pressure

freezing-point

confinement

kelvin equation

Författare

D. Nowak

University of Leeds

M. Heuberger

Eidgenössische Technische Hochschule Zürich (ETH)

Forschungsinstitution fur Materialwissenschaften Und Technologie Eth-Bereichs

Michael Zäch

Chalmers, Teknisk fysik, Kemisk fysik

H. K. Christenson

University of Leeds

Journal of Chemical Physics

0021-9606 (ISSN) 1089-7690 (eISSN)

Vol. 129 15 154509 (article no.)-

Ämneskategorier

Den kondenserade materiens fysik

DOI

10.1063/1.2996293