DISSOCIATION ENERGY AND IONIZATION POTENTIAL OF SILICON MONOXIDE

The dissociation energy of SiO(g) has been determined mass spectrometrically by studying the isomolecular equilibrium Ge(g)+SiO(g) = GeO(g)+Si(g). Third-law calculations lead to ΔH298=26.6± 2 kcal/mole for the reaction, which yields D°0(SiO) = 182.8±3 kcal/mole, or 7.93±0.13 eV. The ionization potentials of SiO and GeO were measured and found to be 11.6±0.2 and 11.5±0.5 eV, respectively. Both of these ionization potentials are higher than previously published values. These data yield D°0(SiO+) = 4.5±0.2 eV, in accord with the results of recent ion-neutral reaction studies. The relation of D°0(SiO) to the bonding in SiO is discussed briefly.