Knowledge Bank

The polarized specular reflection spectra of chloranil single crystals have been obtained for the a, b and c axes from 400 nm to 220 nm. Two intense transitions are observed near 32kK and 45kK and are assigned as long axis $\pi \ast \leftarrow \pi$ transitions. The pure crystal spectrum appears to be a case of electronic intermediate coupling in the case of the low energy band and of weak coupling in the case of the higher energy band. The crystal data are compared to calculated splittings.