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.
Acknowledgements
G.D.L. and L.F. acknowledge the financial support of the Università di Bologna and the Ministero dell’Istruzione dell’Università e della Ricerca (PRIN ‘Spettroscopia molecolare per la Ricerca Atmosferica e Astrochimica: Esperimento, Teoria ed Applicazioni’). D.B.P. and R.Z.M. acknowledge the financial support of the Ministry of Science and Innovation through research grant FIS2009-08069.