High-resolution infrared analysis of the ν7 band of cis-ethylene-d2 (cis-C2H2D2)

The spectrum of the ν7 band of cis-ethylene-d2 (cis-C2H2D2) has been recorded with an unapodized resolution of 0.0063 cm−1 in the 740-950 cm−1 region using a Bruker IFS 125 HR Fourier transform infrared spectrometer. By fitting 2186 infrared transitions of ν7 with a standard deviation of 0.00060 cm−1 using a Watson's A-reduced Hamiltonian in the Ir representation, accurate rovibrational constants for ν7 = 1 state have been derived. The band center of ν7 has been found to be 842.20957 ± 0.00004 cm−1. In a simultaneous fit of 1331 infrared ground state combination differences from the present ν7 transitions, together with 22 microwave frequencies, ground state constants have been improved. The rms deviation of the ground state fit was 0.00027 cm−1.