Activated barrier crossing dynamics in the non-radiative decay of NADH and NADPH

► NADH and NADPH have a high rate of non-radiative excited state decay. ► Conformational relaxation is shown to be a significant non-radiative pathway. ► The Kramers equation describes the barrier crossing dynamics of the relaxation. ► Conformational restriction upon enzyme binding will alter NAD(P)H lifetimes.