EMISSION-SPECTRA IN KI-TL AND RBI-TL PHOSPHORS WITH CSCL-TYPE STRUCTURE

KI: T1 crystal shows a drastic change in the emission and excitation spectra upon the phase transition from the NaCl phase to the CsCl phase under hydrostatic pressure. There appears two sets of the A-like emission and their corresponding excitation bands. It seems that in the CsCl phase, there exist two similar excited states with the A-like adiabatic-potential-energy surface having two kinds of minimum points, that is, in the CsCl phase the one corresponding to the A state in the NaCl phase and another new one like the A state. The measurement of the pressure effects is carried out at 1.5 K to avoid thermal quenching. © 1979 The American Physical Society.