THE NU-3 FUNDAMENTAL IN C2H2

Absolute line positions and intensities are provided for the ν3 fundamental in C2H2 with an accuracy estimated to respectively 6 × 10-4 cm-1 and 0.05 cm-2 atm-1. Unperturbed values are derived for the energy and intensity parameters by treating the Fermi-type resonance and k-doubling effects involved through the interaction with the ν2 + ν4 + ν5 level. The complete set of k-components is included in the procedure. Fitting procedures are carried our on the line energies, the line intensities, and both sets of information simultaneously. The main results are, for the deperturbed values: E(ν3) = 3288.58075(13) cm-1, E(ν2 + ν4 + ν5) = 3296.79650(9)cm-1, k2345 = 25.86749(13) cm-1, and the transition moments Rv(ν3) = ±0.08907(3) D and Rv(ν2 + ν4 + ν5) = ∓2.63(3) × 10-3 D. with the errors (1σ) quoted on the last digits. The mixing between the various levels is quantitatively discussed. © 1993 Academic Press, Inc.