摘要:
Spectra of pure rotational transitions of the very weakly bound He-CO2 van der Waals complex were investigated using a pulsed molecular beam Fourier Transform microwave spectrometer. The complex exhibits very large amplitude internal vibrational motions and the rotational transitions were, as a consequence, difficult to locate and to assign. Eight isotopomers, namely He-CO2, He-(CO2)-C-13, He-(OCO)-O-18, He-(OCO)-C-13-O-18, He-(OCO)-O-18-O-18, He-(OCO)-O-18-C-13-O-18, He-(OCO)-O-17, and He-(OCO)-C-13-O-17, Were studied in order to establish the assignments. The hyperfine structures due to the quadrupolar O-17 nucleus were resolved and analyzed in the two O-17 containing isotopomers. The observed nuclear quadrupole hyperfine structures not only provide further confirmation for the assignment but also give new information about the angular anisotropy of the He-CO2 interaction potential. (C) 2001 Elsevier Science B.V. All rights reserved.