Thermodynamic stability of Sn4, Sn5, Sn6, and Sn7 clusters by Knudsen cell mass spectrometry

The Knudsen cell mass spectrometric method has been employed to measure the partial pressures of Snn (n=1–7) under equilibrium conditions above liquid tin or a tin–gold alloy, contained in a graphite Knudsen cell. From the all-gas analyzed equilibria the following atomization enthalpies ΔaH0∘(Snn), and enthalpies of formation, ΔfH298.15∘(Snn), in kJ mol−1, have been obtained: Sn4, 750.2±14 and 450.6±14; Sn5, 990.2±22 and 512.3±22; Sn6, 1349.7±28 and 452.8±28; Sn7, 1644.2±37 and 460.0±37. The atomization energies are compared with available theoretical values.