Acetylene, 12C2H2: new CRDS data and global vibration-rotation analysis up to 8600 cm-1

Michel Herman (1)

1 Service de Chimie Quantique et Photophysique

The absorption spectrum of 12C2H2 has been recorded using cavity ring downringdown spectroscopy and analyzed in the ranges 60006356 cm and 66677015 cm. Fourteen new bands have been identified and additional J-lines were assigned in 10 already known bands. These new data, together with the published vibration-rotation absorption lines of 12C2H2 accessing vibrational states up to 8600 cm have been gathered in a database. The resulting set includes 12137 transitions involving 186 different k = l4 + l5 sub-states, with li the angular momentum quantum number associated to the i degenerate bending vibration. These lines have been fitted simultaneously to spectroscopic parameters through J-dependent Hamiltonian matrices exploiting the vibrational polyad or cluster block-diagonalization, in terms of the pseudo quantum numbers Nr = 5v1+3v2+5v3+v4+v5 and Ns = v1+v2+v3, also accounting for k and e/f parities and u/g symmetry. Modes 1 and 2 correspond to the symmetric CH and CC stretchings, mode 3 to the antisymmetric CH stretch, and modes 4 and 5 to the trans- and cis-degenerate bendings, respectively. The fit was successfully achieved, with a dimensionless standard deviation of 0.92, leading to the determination of 266 effective vibration-rotation parameters.

Mots clés: Physical Sciences

Michel Herman. Acetylene, 12C2H2: new CRDS data and global vibration-rotation analysis up to 8600 cm-1. Molecular Physics, 2008, 106 (21-23), pp.2581-2605. ⟨10.1080/00268970802620709⟩. ⟨hal-00513240⟩