Cluster formation of a seed component in rare gas free jet expansions

Mass spectrometric measurements of dimer content in supersonic Ar molecular beams are in excellent agreement with previous measurements, and in very good agreement with the concentration of dimers predicted by Knuth’s sudden freeze analysis. Dimer concentrations in krypton and xenon expansions from a 0.0025 cm orifice also scale according to Knuth’s equation, but results of expansions of these gases through a 0.005 cm orifice do not scale with orifice dimension. Dimerization of XeF6 seeded into the rare gas carreers does not follow the hard sphere ternary collision rates. The XeF6 dimer concentration from the expansions apparently depends directly upon the degree of condensation of the carrier gas. Similarly, condensation of (XeF6)n, n≳2, also depends directly upon the extent of rare gas carrier condensation, and these experimental results are compatabile with a two body displacement reaction mechanism for the production of XeF6 oligomers.