Assignment of the triplet factor group states of benzene

The pure electronic 1Ag-3B1u transition of crystalline benzene has been measured by photoexcitation techniques. Polarization and Zeeman measurements on single crystals provide the following assignment of the factor group states (energies relative to the mean value): B3u-7.8 cm-1, Au-0.3 cm-1, B 1u+2.6 cm-1, B2u+5.5 cm-1. These results are in contradiction with the most recent calculations performed within the neutral exciton model. The relative intensity of the factor group states suggests that other crystal states do contribute to the transition. Copyright © 1977 American Institute of Physics.