VIBRATION-ROTATION SPECTRA OF C-13-CONTAINING ACETYLENE - THE STRETCHING FUNDAMENTALS

High-resolution vibration-rotation spectra of the stretching fundament als of (C2H2)-C-13 and (CCH2)-C-12-C-13 have been recorded at Doppler- or pressure-limited resolution in the 8-, 4-, and 3-mu m spectral reg ions. Both cold and hot bands involving stretching and stretching-bend ing combination levels have been analyzed. The complete treatment of t he weak quartic anharmonic resonance between the levels nu(3) and nu(2 ) + nu(4) + nu(5) (Sigma(u)(+))in (C2H2)-C-13 has been performed, yiel ding the effective anharmonic constant K-2345 and the unperturbed valu e of the nu(3) fundamental for this isotopomer. The analysis of the ba nds of the (CCH2)-C-12-C-13 isotopomer provides values for vibrational energies and rotational constants of the first excited states of all stretching vibrations, including the nu(2) = 1 level, not detected bef ore in IR spectra. (C) 1995 Academic Press, Inc.