Homogeneous nucleation rate measurements in 1-pentanol vapor with helium as a buffer gas

Abstract

Nucleation is an integral part of vapor to condensed phase transitions. In most situations, the heterogeneous nucleation that occurs in presence of foreign nuclei, aerosol particles, ions, or surfaces is of the utmost importance. If nucleating sites are not present, condensation takes place by vapor deposition on its own embryos. This process is termed homogeneous nucleation. This chapter studies the rate of homogeneous nucleation in supersaturated vapors of n-pentanol experimentally using an upward static diffusion chamber. Helium was used as a buffer gas, holding the total pressure in the chamber at 25 kPa. A recently improved photographic technique was used to determine the nucleation rate as a function of supersaturation at 260 K temperature. This dependence was compared with prediction by classical theory of homogeneous nucleation. 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.