Mass Spectrometric Studies at High Temperatures. III. Dissociation Energies of the Alkaline Earth Monofluorides

By heating the difluorides of magnesium, strontium, and barium under reducing conditions, one obtains significant amounts of the respective monofluorides. Mass spectrometric studies of equilibria involving these monofluorides have yielded the dissociation energies (D°298) 4.62±0.1 eV, 5.43±0.1 eV, and 5.83±0.1 eV for gaseous MgF, SrF, and BaF, respectively. These results support an ionic model for these molecules and are considerably higher than those previously accepted.