Atomization enthalpies and enthalpies of formation of the germanium clusters, Ge5, Ge6, Ge7, and Ge8 by Knudsen effusion mass spectrometry

Abstract

The high-temperature mass spectrometric method was employed to measure the equilibrium partial pressures of small germanium clusters above liquid germanium contained in a graphite Knudsen cell. These data were combined with new thermal functions, calculated from recent theoretical and spectroscopic molecular parameters, to evaluate the atomization enthalpies and enthalpies of formation of Ge5–Ge8. Mass spectrometric equilibrium data available in literature were also reevaluated. The following atomization enthalpies, ΔaH0o(Gen,g) and enthalpies of formation ΔfH298.15o(Gen,g), in kJ mol−1, have been obtained: Ge5, 1313±27 and 548±27, Ge6, 1649±33 and 583±33, Ge7, 2008±42 and 598±42, Ge8, 2359±60 and 618±60. The atomization energies are compared with available theoretical values.