Ab initio study of excited electronic states and vibronic spectra of phenyl radical

Geometries, vibrational frequencies, excitation energies, and vibronic spectra of seven excited states of C6H5 have been studied by multireference ab initio calculations. For the 12B1,12B2,22B2, and 22B1 states the most intense vibronic peaks are calculated at 17952, 37744, 43380, and 43251 cm−1, respectively, and for 12A2, 22A1, and 32A1 upper estimates for adiabatic excitation energies are 22176, 30988, and 42543 cm−1. We have assigned the 530–440 nm band in the absorption spectra to 12B1 with possible contribution from 12A2, the 265–230 nm band to 12B2 and 32A1, and intense peaks starting from ∼212 nm to 22B1 and 22B2.