De-excitation Rates of Excited Electronic States in Solids

The importance of the vibrational state in spontaneous radiative and nonradiative electronic transitions is discussed. It is argued that in most cases vibrational excitation enhances these transition probabilities, and numerical results are presented for a range of parameters for a simple model of radiationless transitions. Special attention is given to the case of very slow vibrational energy transfer to the environment, particularly from complex excited molecules.