Clinton T. Mills’s research while affiliated with University of Canterbury and other places

The Onsager heat of transport Q* has been determined by measuring the effect of a temperature gradient at the interface on the apparent vapor pressure of the liquid. Results for n-heptanol extend to pressures that are low enough for the separation between the liquid and the warmer surface above it to be less than one mean free path. At low pressure, the dependence of ΔP on ΔT is found to be linear, in contrast to the curves obtained when the separation is greater than a mean free path. As with aniline, the heat of transport is negative and its magnitude approaches the latent heat of vaporization at low pressures. The results are discussed in relation to three anomalous effects that have been predicted or observed during steady-state evaporation and also in relation to the problem of determining rates of air−sea exchange for atmospheric gases.

We report the condensation of aniline vapour upon a surface which is significantly warmer than the liquid from which the vapour originated, and show that this apparently paradoxical behaviour is predictable on the basis of our recent measurements of the Onsager heat of transport at the aniline liquid–vapour interface. In the previous experiments, which for experimental reasons were restricted to positive temperature gradients, we measured the increase in vapour pressure produced by the applied temperature gradient. The present results imply that a negative temperature gradient at the surface produces a similar decrease in the vapour pressure.

Recent measurements of the Onsager heat of transport at the aniline liquid–vapour interfaced revealed phenomena which are not considered by the standard gas-kinetic treatments of evaporation and condensation. Here we show that these experiments support the existence of the inverted temperature profiles that have been predicted by theoretical treatments of the two-surface problem.

The heat of transport for passage of matter through a gas–liquid interface has been determined for the aniline li-quid–vapour system, by measuring stationary-state pressure differences produced by known temperature differences over a distance of 2 mm on the vapour side of the interface. For the range of pressures used, 2 mm is between 6 and 34 mean free paths. Coupling of the heat and matter fluxes is significant over the whole of this range. At the higher pressures the heat of transport is more than 20% of the heat of condensation; at the lower pressures it is more than 50%. Ó 2002 Elsevier Science B.V. All rights reserved.

The measured quantum yield of CO2 is 1.2% for acid strengths in the range 80–100 wt.% under conditions in which the yield varies linearly with the average laser power and is independent of the CO flow. The yield of SO2 is highly variable and may be either positive or negative. These observations lead us to discard our previously postulated mechanism in favour of one involving the production of atomic oxygen in the primary photolysis step. The highly variable and negative yields of SO2 are accounted for by postulating the formation of varying amounts of peroxysulfuric acid in the irradiated droplets.