Benzene, absorption spectrum rotational constants

D. A. Ramsay and co-workers has provided many constants for one of the excited singlet states CAJ of glyoxal, and the rotational structure within many of the vibrational levels of this state can be described with exceedingly high precision. Benzene, the subject of the present discussion, is another example where a fairly detailed description of numerous stationary aspects of both the ground and upper electronic states are now available. As a result of Callomon, Dunn, and Mills beautiful analysis of rotational band contours in the ultraviolet absorption spectrum, much is known about even the Coriolis constants for vibronic levels in the excited singlet state. Numerous other examples could be cited in which the geometries and many upper state constants in polyatomics are well known. 

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