Determination by the mass spectrometric Knudsen cell method and discussion of the dissociation energies of the molecules Se2(g), SSe(g) and SeTe(g)

The dissociation energies of the molecules Se2(g), SSe(g) and SeTe(g), D°0(Se2)= 78.1 ± 2.0, D°0(SSe)= 87.8 ± 1.6 and D°0(SeTe)= 70.1 ± 1.2 kcal mol–1 are determined by the mass spectrometric Knudsen cell method. For Se2, the result confirms the higher of two spectroscopically possible values, D°0(Se2)= 78.65 ± 0.06 kcal mol–1, which has not been favoured hitherto on spectroscopic grounds. The spectroscopic observations are, therefore, critically examined to show that they allow this value.