Raman spectral analysis of the intermolecular hydrogen bond in bromoform

The maximum of the perpendicular polarized component of the Raman spectrum of the C−H mode in liquid bromoform shifts by 1.5 cm−1 toward higher frequencies from the maximum of the parallel polarized component. A high-frequency shift of this band is noted in solution with nitromethane and nitrobenzene, and the shape of the band becomes more complex. The result is attributed to superposition of the associate lines in the mixture (the high-frequency component) and the monomer line. There are indications that the 537 cm−1 band of bromoform in a mixture with the same solvents and with pyridine has a doublet character. When CHBr3 is dissolved in a neutral solvent such as heptane, both bands exhibit normal behavior, the widths of the lines decreasing presumably because of an increase in the vibrational relaxation time.