The 2000 Å absorption system of the benzene single crystal in polarized light

Abstract

The 2000 Å absorption system in the benzene single crystal is investigated at liquid nitrogen temperature. The analysis of the polarized spectra recorded along b and c in (100) plates appears to be not in favour of the assignment of the π* └π system to an upper state of B 1u symmetry, and it is not in contrast with the hypothesis of a 1 E 2g upper state. The first band in the system, located at 46 565 cm-1, and totally polarized along c, is discussed in terms either of an out-of-plane false origin of the 1 E 2g └1 A 1g system, or of a new transition lying between the first two well known π-systems of benzene, possibly of π* └σ type.