A further simplification can be taken where for large energy gaps, the first term on the right-hand side of Equation 22 can be ignored; this is formally a generalised relation of the energy gap law in non-radiative decay . In addition, analysis of optical selection processes within the Condon approximation , which assumed any electronic coupling was independent of the initial vibronic state, assuming that the electronic coupling matrix element is independent of the initial vibronic state. While a shift of less than 2% was seen in the vibronic level of S 1 benzene due to the derived non-Condon correction term , it is apparent that an internal conversion decay probability is strongly dependent on the amount of excess vibrational energy, since higher normal modes may be allowed to participate in the transition.