A mass spectrometric study of heteronuclear diatomic alkali metal molecules. Dissociation energies and ionization potentials of NaLi, KLi, and NaK.

Abstract

The gaseous molecules NaLi, KLi, and NaK were studied by equilibrium and electron impact techniques. The dissociation energies of these molecules were determined from the second and the third law enthalpies of various equilibria, and the following values were obtained: D00(NaLi) =20.7±1.5 kcal/mole, D00 KLi) =18.7±1.0 kcal/mole, and D00(NaK) =14.6±1.0 kcal/mole. Electron impact measurements yield values of 4.94±0.10, 4.69±0.10, and 4.57±0.20 eV for the ionization potentials of NaLi, KLi, and NaK molecules, respectively. The results are compared with spectroscopic data and recent theoretical calculations. The relation of these results to the bonding in heteronuclear diatomic alkali metal molecules is discussed.