Abstract
The gas evaporation method, which is a typical smoke experiment, has a history of almost half century. Nevertheless, there has been almost no report concerning nucleation in a smoke in view of crystal growth. Here, we observed a nucleation process of thermally evaporated manganese vapor in an argon gas using a Mach-Zehnder type interferometer and showed that nanoparticles homogeneously condense only in very highly supersaturated environments. Condensation occurred at 660-785 K well below the equilibrium temperature and the degree of supersaturation was as high as ~5×104. Based on the condensation temperature and size of the condensed particles, which were measured by transmission electron microscopy, we determined the surface free energy and sticking coefficient for nucleation of Mn at 1106 ± 50 K to be 1.57 ± 0.35 J/m2 and 〖0.42〗_(-0.21)^(+0.42), respectively, by means of a semi-phenomenological (SP) nucleation theory. The large errors in these two parameters will be decreased by microgravity experiments.
