Resonance vibrational energy transfer in liquids in the repulsive potential region

It was found that the resonance vibrational energy transfer caused by the short−range repulsive part of the intermolecular (perturbing) potential may play an important role as mechanism to produce broadening of vibrational band contours of molecules in the liquid state. The value of the full bandwidth at the half peak height (Δν1/2) for the ν4 (C−H deformation) fundamental of neat chloroform (8.2 cm−1) was reduced to 6.2 cm−1 at infinite dilution with deuterochloroform. This difference in Δν1/2 can be reproduced by either the above repulsive mechanism or by resonance energy transfer caused by the long−range transition dipole−transition dipole interactions. Physical aspects of these mechanisms are discussed and compared with those of NMR relaxation. The significance of the repulsive resonance transfer process with respect to transition state theory is indicated.