VIBRATION-ROTATION SPECTRA OF C-13 CONTAINING ACETYLENE - ANHARMONIC RESONANCES

High resolution vibration-rotation spectra of (C2H2)-C-13 were recorde d in a number of regions from 2000 to 5200 cm(-1) at Doppler or pressu re limited resolution. In these spectral ranges cold and hot bands inv olving the bending-stretching combination levels have been analyzed up to high J values. Anharmonic quartic resonances for the combination l evels nu(1) + m nu(4) + n nu(5), nu(2) + m nu(4) + (n + 2)nu(5) and nu (3) + (m - 1)nu(4) + (n + 1)nu(5) have been studied, and the l-type re sonances within each polyad have been explicitly taken into account in the analysis of the data. The least-squares refinement provides deper turbed values for band origins and rotational constants, obtained by f itting rotation lines only up to J approximate to 20 with root mean sq uare errors of approximate to 0.0003 cm(-1). The band origins allowed us to determine a number of the anharmonicity constants x(ij)(0).