Mass spectrometric investigation of the thermodynamic properties of the Si6 molecule

Partial pressures of Si(g) and Si6(g) over condensed silicon have been measured by Knudsen cell mass spectrometry. The atomization energy and enthalpy of formation of Si6(g) was evaluated for the reaction Si6 (g) = 6Si(g) with these partial pressures and with thermal functions derived from recent experimental and theoretical molecular parameters. The results, ΔaH0[Si6(g)] = 1981 ± 32 kJ mol−1 and ΔfH298.15[Si6(g)] = 733 ± 41 kJ mol−1 are compared with predictions from recent theoretical calculations.