Raman Lines of Simple Polyatomic Molecules

Abstract

IN the course of a study of the structure of simple polyatomic molecules, the Raman spectrum of hydrazine, N₂H₄, was obtained with the view of finding the Raman line or lines which correspond to the symmetrical vibration N-N in polyatomic molecules. We should expect to find a line in the neighbourhood of 1600 cm.⁻¹, but the hydrazine spectrum showed three lines of roughly equal intensity at 3196 cm.⁻¹, 3270 cm.⁻¹, and 3344 cm.⁻¹, along with a very doubtful line at 1720 cm.⁻¹. These three lines are obviously due to N-H vibrations, and it seems curious that the symmetrical vibration should be so weak (if present at all) in the spectrum of this molecule.