The polarized charge-transfer spectrum of crystalline anthracene-TNB complex

Abstract

The intermolecular charge-transfer spectrum of the crystalline anthracene-TNB complex has been measured, using polarized light. The crystal spectrum differs from that of the solution to a much greater degree than is the case for ordinary aromatic systems. The transition is polarized along the intermolecular axis and is blue-shifted with respect to the solution. There is pronounced vibrational structure, including a prominent 250 cm^-1 interval. A Davydov splitting of approximately 200 cm^-1 is observed, and this is shown to be in reasonable agreement with the known crystal structure and with the symmetry assignment of the transition, which is A′ ← A′ for the complex in solution and A ← A in the crystal.