An earlier model for calculating zero temperature radiative and non-radiative decay rates has been extended to include relaxation from higher vibrational levels of an excited electronic state which, including the Boltzmann distribution, leads to a model that allows investigation of temperature dependence. In this procedure the lineshapes are expressed by generalized intra-molecular distributions, which can be defined by various representations. For the case where there is more than one accepting mode, intramolecular distributions of higher order have been introduced, which for certain parameter symmetries (resulting, for example, from vibrational degeneracy) can be reduced to low dimensional intramolecular distributions. Some specific intramolecular distributions are calculated using parameters which represent different vibronic coupling cases. This leads to a discussion of several types of decay rates.