Dissociation Energies of Group IIIA Monofluoridesmdash;The Possibility of Potential Maxima in Their Excited Pgr; States

摘要

The dissociation energiesD0Prime; have been measured for GaF, InF, and TlF using highhyphen;temperature masshyphen;spectrometric techniques. These results, along with those from previous studies, yieldD0Prime;=180plusmn;3, 159plusmn;3, 138plusmn;3.5, 121plusmn;3.5, and 101plusmn;3.5 kcal/mole for BF, AlF, GaF, InF, and TlF, respectively. Comparison ofD0Prime; thus obtained with that derived from Birgemdash;Sponer extrapolation of theA1Pgr; state indicates that for all these molecules the spectroscopically derived dissociation energies are higher than the thermochemical values. It is suggested that the difference may be due to a potential maximum in theA1Pgr; states BF, AlF, GaF, and InF. A maximum is also suggested for thea3Pgr;1state of TlF. The appearance potentials of these monofluorides were measured and were found to be 11.5plusmn;0.4, 9.5plusmn;0.5, 10.6plusmn;0.4, 9.6plusmn;0.5, and 11.2plusmn;0.5 eV for BF+, AlF+, GaF+, InF+, and TlF+, respectively. The dissociation energies and the appearance potentials are briefly discussed in terms of the molecular states of the respective molecules.