The initially bright 1 ππ* state of the 7H tautomer can decay directly to the ground state via puckering of the 5-membered subunit or by fluorescence, on the order of 25 ns. (ii) Alternatively, 7H 2,6-dAP can undergo intersystem crossing (ISC) to T 2 ( 3 ππ*). The relative yields do not appear to depend on excitation wavelength, based on the relative amplitudes of the decay traces (Fig. ).