PHOTOIONIZATION SPECTROSCOPY OF Ga-RARE GAS COMPLEXES

New electronic states, F 2Δ3/2, G 2Δ5/2, H 2Π1/2, and I 2Π3/2, are investigated for the complexes GaAr, GaKr, and GaXe with resonant two-photon photoionization spectroscopy. These excited states correlate to the 2D←2P (4d←4p) atomic transition of gallium. Vibronic structure in these spectra are used to obtain vibrational constants, and extrapolated progressions are used to determine dissociation energies. The upper 2Δ states are more than twice as strongly bound as the corresponding 2Π states. Excited state values of dissociation energies are used in energetic cycles to determine ground-state dissociation energies for GaAr, GaKr, and GaXe. In all three cases, the values obtained are significantly lower than previous estimates. The ground state of GaAr is extremely weakly bound, with D0″=20±20 cm−1, while the corresponding value for GaKr is only 35±20 cm−1. The B 2Σ+ excited states of the Ga–RG complexes are confirmed to have substantial barriers in their long-range potentials.