IR spectra of CH2I2 in Ar and N2 cryomatrices: Evidence of unusual band splitting in N2 matrix

Abstract

Matrix isolation IR spectra of in matrix are analysed using IR spectra obtained in the Ar matrix, quantum chemical calculations, and molecular point group symmetry to determine the origin of the unusual splitting observed in the antisymmetric stretching (), rocking (), wagging (), and antisymmetric stretching () modes of only in matrix and not in Ar matrix. The , , , and vibrational modes belong to either or irreducible representations under point group symmetry. IR spectra in matrix is reported for the first time. IR spectra recorded in Ar matrix are consistent with previous reports. Electronic structure calculations have been performed to obtain simulated IR spectra of with and point group symmetries, conformers, [-], and [-]. IR spectra obtained in Ar and matrices originate from , , and splitting of IR peaks in matrix. Splitting of the IR peaks of in solid state is described by Davydov splitting or factor group splitting. The observed splitting of IR peaks in matrix is due to the lowering of symmetry of from to one of its sub groups due to the perturbation of the rigid matrix that possess quadrupole moment.