SOLID-STATE EFFECTS ON NONRADIATIVE DECAY OF 4D(9)4F(1) STATES IN BARIUM HALIDES

The nonradiative decay of 4d(9)4f1 states in barium halides was investigated by using resonant-photoemission spectroscopy. Constant-final-state spectra with the final state at N4,5-O2,3O2,3 Auger electron peak and constant-initial-state (CIS) spectra with the initial state at Ba 5p levels were enhanced in the Ba 4d excitation-energy region, indicating Auger and direct recombination decay processes, respectively. The probability of the direct recombination decay was estimated from the CIS and the absorption spectra. At the excitation energy of the 4d(9)4f1 (3D) state, the intensity ratio Of 5p1/2 to 5p3/2 photoelectrons showed the anomalous increase due to the different branching ratio in the direct recombination process. It was noticed that the decay probability through the direct recombination process and the degree of the anomalous branching ratio increase in the order of BaF2, BaCl2, and BaBr2. This result indicates that the nonradiative decay of the 4d(9)4f1 states in the barium halides is affected by crystalline environments.