Polarized Raman spectra IX. Low Frequency Vibrations in Crystallne Trans‐Stilbene

Abstract

Raman spectrum of powdered crystalline trans-stilbene is recorded by a laser Raman spectrometer. The intensity of a low frequency skeIeton bending vibration at 220 cm-'iS observed to be very weak. Its Raman intensity, after corrected for the photocathode response and for the v4 scattering factor, agrees within 10% of the theoretically caIcuIafed value. It is therefore proved that the intensity of a Raman active vibration is proportional to the square of its vibrational frequency, if only one excited state is involved in the scattering process, Lattice vibrations in trans-stilbene crystal are also reported.