title: From adsorption to condensation: the role of adsorbed molecular clusters.
abstract: The adsorption of heptane vapour on a smooth silicon substrate with a lower temperature than the vapour is examined analytically and experimentally. An expression for the amount adsorbed under steady state conditions is derived from the molecular cluster model of the adsorbate that is similar to the one used to derive the equilibrium Zeta adsorption isotherm. The amount adsorbed in each of a series of steady experiments is measured using a UV-vis interferometer, and gives strong support to the amount predicted to be adsorbed. The cluster distribution is used to predict the subcooling temperature required for the adsorbed vapour to make a disorder-order phase transition to become an adsorbed liquid, and the subcooling temperature is found to be 2.7 ± 0.4 K. The continuum approach for predicting the thickness of the adsorbed liquid film originally developed by Nusselt is compared with that measured and is found to over-predict the thickness by three-orders of magnitude.
authors.affiliation: Thermodynamics and Kinetics Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, CanadaM5S 3G8. charles.ward@utotonto.ca.
authors.forename: Sima
authors.initials: S
authors.lastname: Yaghoubian
authors.affiliation: Thermodynamics and Kinetics Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, CanadaM5S 3G8. charles.ward@utotonto.ca.
authors.forename: Seyed Hadi
authors.initials: SH
authors.lastname: Zandavi
authors.affiliation: Thermodynamics and Kinetics Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, CanadaM5S 3G8. charles.ward@utotonto.ca.
authors.forename: C A
authors.initials: CA
authors.lastname: Ward