Benzene 'dimers' formed by excitation transfer interaction (J), in weakly disordered aggregates, have been observed in atactic polystyrene films (200-2500 Angstrom thick) spin-coated on fused quartz, through presence of a doublet in the main vibronic M-band in the (1)A(1g) --> B-1(2u) optical singlet band. Only V-shaped 'dimers' were found with dihedral angle (alpha) varying from 90degrees to 107degrees with no apparent dependence on film thickness. A model for the 'dimer' consistent with observed J(g) yields the value of the transition moment and provides the 'dimer' geometry. (C) 2004 Elsevier B.V. All rights reserved.