Knowledge Bank

High resolution data ($1\circ K$) reveal a rich fine structure of the vibronic bands of naphthalene (about 1% guest in durene host). The data will be discussed in terms of resonance pairs (``dimers'') of the guest: The guest-guest resonant transfer of excitation energy when two guest molecules happen to occupy adjacent host sites. This system is ideally suited for the study of excitation exchange interactions of the kind responsible for exciton states in neat crystals as well as energy transfer in the gas phase. An interacting molecular pair in this system has both fixed position and orientation. It gives rise to a faithful pairwise interaction term directly measurable, in contradistinction to the sum of pairwise(and manywise) terms related to Davydov splittings and other neat crystal data.