Pulling the Levers of Photophysics: How Structure Controls the Rate of Energy Dissipation

Internal conversion: The energy difference between the Franck–Condon and equilibrium geometries and the vibrational frequency of one or a few modes determine the relative importance of adiabatic and nonadiabatic dynamics and thus the rate of electronic energy dissipation (see picture). In the cycloketones, variations in these quantities lead to a difference in the timescale for the S2→S1 transition.