The bending vibrations in ¹²C₂H₂: global vibration-rotation analysis: Global vibration-rotation analysis

A total of 3155 vibration-rotation line positions providing accurate information on all known vibration-rotation states up to 3000 cm-1 in 12C2H2 were gathered from the literature. An additional 966 lines were assigned on new spectra. The full data set was simultaneously fitted using an appropriate Hamiltonian, with 85 refined parameters. A dimensionless standard deviation equal to 0.86, accounting for 92% of the lines, was achieved. The vibrational transition dipole moment of the 5 = 1 4 = 1 band observed in the far-infrared was estimated to be |μ5←4| = 0.55 D with 20% accuracy, from absolute intensity measurements for a few Q-branch lines.