POTENTIAL-ENERGY SURFACE FOR AND PURE ROTATIONAL SPECTRA OF ISOTOPOMERIC CL-2-AR VAN-DER-WAALS COMPLEXES

Pure rotational spectra have been calculated for the three isotopomers of the Cl-2-Ar van der Waals complex formed by Cl-2 in its ground ele ctronic state. The potential energy surface involved is a sum of pairw ise. Morse atom-atom interactions, which are merged asymptotically int o an anisotropic van der Waals form. The Morse atom-atom interactions have been refined by adjusting their parameters to obtain agreement wi th both excitation spectra and recent microwave transitions observed f or the Cl-35(2)-Ar van der Waals complex, whereas the anisotropic long -range part of the potential surface has been taken from ab initio res ults [Mol. Phys. 80, 533 (1993)]. The present model potential surface predicts a T-shaped structure for the complex, in agreement with exper iment. Excellent agreement has been found between the calculated and e xperimental microwave transition frequencies for the (ClCl)-Cl-35-Cl-3 7-Ar complex. Good agreement has also been found between the experimen tally determined bond energy, bond length, and average ''bond angle'' governing the overall geometry of the complex and the corresponding qu antities determined from dynamical calculations based upon the present potential surface. The new potential surface has also been utilized t o predict the microwave spectrum of the Cl-37(2)-Ar isotopomer. (C) 19 96 American Institute of Physics.