Aggregation induced spectral splitting and Fermi resonance of Ethylene Carbonate in binary mixture.

[Display omitted] • Four frequencies have been observed in the iso and aniso Raman spectra of EC. • Fermi constant W, NCE value V1 and V2 have been determined at different concentration. • Dimer structure and DFT calculations can reproduce the NCE and concentration effects. The vibration band of the ring stretching (ν 14), the fundamental ring breathing (ν 17) and the Fermi resonance band of carbonyl stretching mixing with the overtone of the ring breathing (ν 5 + 2ν 17) have been investigated in solid ethylene carbonate (EC) and EC/CH 3 CN and EC/CHCl 3 binary mixture. Dimer structure with aggregation-induced spectral splitting model (AIS) was applied to calculate the vibration spectra using the B3LYP-D3/6-311+G (d,p) procedure. The noncoincidence effect (NCE) and concentration induced frequency shifts of the ν 14 and ν 5 could be well explained by AIS model based on the dimer structure. Four bands were observed with two in the isotropic and two in the anisotropic Raman spectra and their NCE value decreased with the decrease of EC volume fraction in the binary mixture, and finally disappeared. NCE value and the Fermi resonance constants of EC at different concentrations were calculated from the experimental data. [ABSTRACT FROM AUTHOR]