Strong and Isotope Selective Effects of the ΔK= ±3 Interaction in the Ground State and in the ν5Infrared Bands of Four Isotopomers of FClO3

✍ Scribed by F. Meguellati; G. Graner; K. Burczyk; H. Bürger; G. Pawelke; P. Pracna

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 360 KB
• Volume: 184
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1997.7339

✦ Synopsis

The infrared spectra of monoisotopic samples of the 35/37 Cl and 16/18 O isotopomers of FClO 3 have been recorded in the region of the n 5 fundamental with a resolution of ca. 3 1 10 03 cm 01 . Several thousand lines have been assigned in each species and ground state molecular parameters have been determined or improved through the use of ground state combination differences. It was shown that an agreement between the ground state parameters of the four isotopomers requires a DK Å {3 interaction with an off-diagonal e term introduced. The main perturbation in the £ 5 Å 1 state is due to a DK Å {3 interaction which has very strong effects because levels differing by 3 units in K can be unusually close. For F 35 Cl 18 O 3 and F 37 Cl 18 O 3 , the effects are largest for kl Å 023 and 026 and give rise to ''perturbation-allowed transitions.'' For F 35 Cl 16 O 3 and F 37 Cl 16 O 3 , the kl Å 05 and 08 levels are closest and no perturbation-allowed transition could be assigned. Two different interaction terms, called e and d, can be defined for such interactions in a degenerate vibrational state. For the first time, they have been both determined significantly and simultaneously for all four isotopomers. They adopt values almost independent of 35 Cl/ 37 Cl substitution and consistent in the 16 O/ 18 O substitution, in spite of very different resonance effects. The axial rotational constants A 0 have also been determined with high accuracy.