Infra-Red and Raman Spectra of Polyatomic Molecules X. C2D2, C2DH, and C2H2

The infra-red spectra of acetylene and its deuterium isotopes have been studied on a prism spectrometer from 450 to 4000 cm—1. All but two of thirty observed bands have been assigned as fundamentals, first and second overtones, and one-one combination or difference bands. Most of the bands of these types which are infra-red active according to the selection rules are either observed or occur in a region where they may be masked by the presence of super-imposed bands.