High Resolution Sub-Doppler Experiments on Benzene
It is shown that sub-Doppler spectroscopy enables one to resolve\nindividual rotational states in the S^ manifold of polyatomic molecules.\nThis i s an essential to the understanding of the primary\nphotophysics within the molecule. Spectra of benzene are found to undergo\nsubstantial changes as the vibrational energy i s raised within S^.\nDue to the increased density of vibrational states, Coriolis coupling,\nwhich is already seen at low energies, can lead to effective IVR above\n3000 cm""1 excess energy. This onset of IVR may be responsible for the\nonset of "Channel Three" in benzene and probably produces gross changes\nin the photophysical behavior of any polyatomic molecule.