The vibrational energy pattern in acetylene.: V.: 13C2H2

A total of 134 vibrational levels with assigned rotational structure have been gathered in the ground electronic state of (C2H2)-C-13. Most of these measurements are updated or new compared to the previously published data. Altogether, they cover the range up to 23 670 cm(-1). 118 out of the 119 levels observed below 13 000 cm(-1) have been simultaneously fitted using the so-called cluster model, already used to deal with the vibrational energy levels in other isotopomers of acetylene [El Idrissi , J. Chem. Phys. 110, 2074 (1999), and references therein]. Twenty-nine vibrational constants have been determined, including the off-diagonal parameters K-3/245, K-1/244, K-1/255, K-11/33, K-14/35, and r(45), with a rms of the fit equal to 0.52 cm(-1). The same three constants of the motion as in (C2H2)-C-12 emerged, N-s=v(1)+v(2)+v(3), N-r=5v(1)+3v(2)+5v(3)+v(4)+v(5) and k=l(4)+l(5). The energies of the levels above 13 000 cm(-1) calculated with the obtained parameters compare reasonably well with the experimental values. For all levels the predicted rotational constants compare satisfactorily with the experimental results. (C) 1999 American Institute of Physics. [S0021-9606(99)00326-8].