THERMAL-DIFFUSION IN THE CRITICAL REGION OF BINARY-LIQUID SYSTEMS

We present results of interferometric measurements of the thermal diff usion factor in the critical regions of the liquid systems n-hexane nitrobenzene (upper consolute point) and water + triethylamine (lower consolute point). In the steady state there is an enrichment of the li ghter component (hexane) or of the heavier component (triethylamine) i n the hotter region in the first or second system, respectively. The a bsolute value of the thermal diffusion factor increases rapidly in the vicinity of a critical solution point and probably becomes infinite i n the critical state.