High resolution infrared and Raman spectroscopy of ν 2 and associated combination and hot bands of 13C12CD2

Abstract

Infrared and Raman spectra of dideuterated acetylene containing one 13C atom, 13C12CD2, have been recorded and analysed to obtain detailed information on the fundamental ν 2 band and associated combination and hot bands. Infrared spectra were recorded at 4 × 10−3 cm−1 resolution in the region 1150−2900 cm−1, which contains combination and hot bands from the ground and the bending v 4 = 1 and v 5 = 1 states. The Q-branches of the ν 2 fundamental and associated hot bands (ν 2 + ν 4 − ν 4, ν 2 + ν 5 − ν 5, ν 2 + 2ν 4 − 2ν 4, ν 2 + 2ν 5 − 2ν 5 and ν 2 + ν 4 + ν 5 − (ν 4 + ν 5)) were recorded using inverse Raman spectroscopy, with an instrumental resolution of about 3 × 10−3 cm−1. In addition, the observation of the 2ν 2 − ν 2 Raman band was carried out populating the v 2 = 1 state by stimulated Raman pumping. In total, 11 Raman and 9 infrared bands were analysed, involving all the l-vibrational components of the excited stretching−bending manifolds up to v t = v 4 + v 5 = 2. A simultaneous analysis of all infrared and Raman assigned transitions has been performed on the basis of a theoretical model which takes into account the rotation and vibration l-type resonances within each vibrational manifold and the Darling−Dennison anharmonic resonance between the ν 2 + 2ν 4 and ν 2 + 2ν 5 states. The parameters obtained reproduce the assigned transition wavenumbers with a standard deviation of the same order of magnitude as the experimental uncertainty.