Homogeneous and Light-Induced Nucleation of Sulfur Vapor Diffusion Cloud Chamber Investigations of Constant Rate Supersaturation

Interesting results were obtained in the initial investigation of the nucleation behavior of supersaturated sulfur vapor up to temperatures above the λ transition. This is a second-order phase transition in liquid sulfur characterized by a change in molecular structure from closed sulfur rings to open radical chains within a narrow temperature range. Although the temperature dependence of the constant rate supersaturation is not correctly represented, it is surprising again how well classical nucleation theory describes experimental results even for such a complex substance. For homogeneous nucleation, there are indications that the λ transition influences the nucleation behavior as a consequence of the changing thermophysical properties density and surface tension of the liquid sulfur. Photoinduced nucleation shows a striking effect directly correlated with the transition. Below the λ temperature, the vapor is extremely sensitive to irradiation with light in the range 260−360 nm that decreases the cons...