Nuclear wave-packet dynamics on nearly degenerate two adiabatic potential energy surfaces in the excited state of KIF centers

Nuclear wave-packet dynamics in the excited state of KI F centers is investigated by using time-resolved luminescence spectroscopy based on the up-conversion technique. The observed transient spectrum involves an oscillatory and a nonoscillatory component. The origins of these components are interrogated by comparing the results with a model calculation based on the resonant secondary radiation theory. The oscillatory part reflects the coupling of the 2s-like electron mainly to the totally symmetric local mode around the F center. The nonoscillatory part reflects the incoherent population of the vibrational levels in the 2p-like state, which couples to many bulk phonon modes with a broad density of state. The model calculation suggests that the transition probability to the 2p-like state is approximately 0.05.