HOMOGENEOUS NUCLEATION RATE MEASUREMENTS IN 1-PENTANOL VAPOR WITH HELIUM AS A BUFFER GAS

The rate of homogeneous nucleation in supersaturated vapors of n-penta nol was studied experimentally using an upward static diffusion chambe r. Helium was used as a buffer gas, holding the total pressure in the chamber at P-t = 25 kPa. A recently improved photographic technique wa s used to determine the nucleation rate as a function of supersaturati on at temperature T = 260 K. This dependence was compared with predict ions made by the classical theory of homogeneous nucleation. Furthermo re, the influence of gaseous ions on nucleation rate was studied, and a minimum voltage across the chamber, necessary to avoid nucleation on ions, was determined. The effect of the wall heating power on nucleat ion was found to be negligible in the range studied. (C) 1998 Elsevier Science B.V.