Improved rovibrational constants for the v7 = 1 state of ethylene-cis-1,2-d2 (cis-C2H2D2) by high-resolution synchrotron FTIR spectroscopy

T. L. Tan, L. L. Ng, M G Gabona, G. Aruchunan, Andy Wong, Dominique R T Appadoo, Don McNaughton

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Using the far-infrared beamline of the Australian Synchrotron, the spectrum of the ν7 band of ethylene-cis-1,2-d2 (cis-C2H2D2) was recorded in the 640–990 cm−1 region at an unapodized resolution of 0.00096 cm−1. A rovibrational analysis of a total of 2823 infrared transitions of the ν7 band was carried out using an asymmetric rotor fitting program based on the Watson's A-reduced Hamiltonian in the Ir representation to derive up to four sextic constants with a rms deviation of 0.00035 cm−1. From the fitting of 2634 ground state combination differences (GSCDs) of cis-C2H2D2 which were derived from the infrared transitions of the ν7 band of this work, and ν10 and ν12 bands of previous studies, together with 22 microwave frequencies, accurate ground state constants of cis-C2H2D2 up to four sextic terms were obtained. The rotational constants (A, B, and C) of the v7 = 1 state of cis-C2H2D2 were found to agree within 0.5% with the calculated values using B3LYP/cc-pVTZ and MP2/cc-pVTZ levels of theory. From this work, the band center of ν7 at 842.209489(20) cm−1 and the rovibrational constants of the v7 = 1 state of cis-C2H2D2 were determined with better accuracy than previously reported.

Original languageEnglish
Pages (from-to)23-27
Number of pages5
JournalJournal of Molecular Spectroscopy
Publication statusPublished - 1 Jan 2017


  • cis-CHD ν band
  • Ethylene-cis-1,2-d
  • FTIR spectroscopy
  • High-resolution infrared
  • Rovibrational constants
  • Synchrotron infrared

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