The overtone dynamics of acetylene above 10 000 cm−1

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Abstract
The 10 000–13 000 cm−1 C–H stretching spectra of normal acetylene have been measured with a high resolution Fourier transform spectrometer and a long path gas cell. Over 400 rovibrational lines were assigned and analyzed yielding band origins and rotational constants. Comparison of calculated and observed rotational constants and intensities confirmed the vibrational assignments made in this region. A vibrational analysis of all observed C2H2 transitions above 10 000 cm−1 was made based on the normal mode constants derived earlier. Some reassignments were made, many unassigned bands were assigned, and several new Fermi resonances were analyzed. When combined with our previous results below 10 000 cm−1, the standard deviation of our analysis for 64 unconstrained states up to 24 000 cm−1 is 9.35 cm−1. Local and global rotational perturbations were noted in our spectra, and the possible identity of the interacting states is discussed. The implication of our results for theories of vibrational energy level structure, intramolecular vibrational relaxation, the C2H2 potential surface, the structure of its phase space, and stimulated emission pumping results on acetylene are discussed.