Evidence for mixed clusters formed during sulfur hexafluoride expansions in an argon carrier gas

Nucleation of sulfur hexafluoride in an argon carrier gas has been studied in very small supersonic adiabatic nozzle expansions. Light scattering is used to detect the onset of condensation, and high-energy electron diffraction is used to ascertain cluster structure for a range of operating conditions where mixed clusters and/or binary nucleation can occur. For the limited range in SF6 mole fraction, χ0=0.01 to 0.03, both the thermodynamic and cluster diffraction data indicate that the SF6 nucleates homogeneously with Ar accruing onto the condensed SF6 after the Ar supersaturates.