Benzene `dimersʹ in polystyrene films

Benzene `dimersʹ formed by excitation transfer interaction (J), in weakly disordered aggregates, have been observed in atactic polystyrene films (200–2500 Å thick) spin-coated on fused quartz, through presence of a doublet in the main vibronic M1-band in the 1A1g→1B2u optical singlet band. Only V-shaped `dimersʹ were found with dihedral angle (α) varying from 90° to 107° with no apparent dependence on film thickness. A model for the `dimerʹ consistent with observed J(α) yields the value of the transition moment and provides the `dimerʹ geometry.