HIGH RESOLUTION SUB-DOPPLER EXPERIMENTS ON BENZENE

I t is shown that sub-Doppler spectroscopy enables one to resolve individual rotational states in the S ̂ manifold of polyatomic molecules. This i s an essential to the understanding of the primary photophysics within the molecule. Spectra of benzene are found to under-go substantial changes as the vibrational energy i s raised within S ̂. Due to the increased density of vibrational states, Coriolis coupling, which is already seen at low energies, can lead to effective IVR above 3000 cm""1 excess energy. This onset of IVR may be responsible for the onset of "Channel Three " in benzene and probably produces gross changes in the photophysical behavior of any polyatomic molecule