Abstract
The low-temperature optical absorption spectrum of the 3A2g to 3T1ga absorption of CaO:Ni2+ is reported. Zeeman studies of the sharp lines within the band show that they arise because of the splitting of the vibronic levels of Ni2+ associated with a localized resonance mode of Gamma 4u symmetry, a phenomenon not observed for any other 3dn system. The splittings due to the quadratic term in the electron-vibration interaction and the relative intensity of the vibronic features are calculated and compared with experiment.
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