Simultaneous intramolecular and intermolecular coupling of polar bond vibrations induced spectral splitting phenomenon

The positions of splitting bands resulting from simultaneous intramolecular (such as Fermi resonance) and intermolecular interactions were calculated by a variational method. Hamiltonian calculation model employed an antiparallel arrangement. Four nondegenerate energy solutions were obtained, which correspond exactly to the four peaks observed in polarized Raman spectroscopy and high resolution infrared spectroscopy: two in the VV component and two in the VH component. The intramolecular coupling constant W, unperturbed intensity ratios R, and unperturbed band difference X 0 for vinylene carbonate (VC) were calculated from the derived equations and the experimental data at infinite dilution concentration. Additionally, the intermolecular interaction constants V of VC in different polar solvents (VC/CH 3 CN, VC/CHCl 3 and VC/CH 3 OH binary mixtures) at varying concentrations were calculated. The curvature of V vs concentration was found to fit the Logan model very well.