Picosecond relaxation processes in excited state quinoxaline

Excited state absorption spectra of quinoxaline in benzene, isooctane, and cis-1,3-pentadiene at 7 and 130 ps after excitation are reported. Picosecond absorption kinetics at 422 and 533 nm are also reported. In the nonaromatic solvents, bands at ∼425 nm (Sn←S1 and Tn←T1) and ∼ 530 nm (mostly Sn←S1) are observed in the transient spectra. Decay of the ∼530-nm band gives k−1isc?23 ps in the nonaromatic solvents. In benzene solvent, the excited state spectra are more complex, the decay kinetics are longer, and quinoxaline–benzene exciplex formation is suggested.