It 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 undergo

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.