ROTATIONAL SPECTRUM OF THE ISOTOPICALLY SUBSTITUTED VAN-DER-WAALS COMPLEX AR-CO2 INVESTIGATED WITH A MOLECULAR-BEAM FOURIER-TRANSFORM MICROWAVE SPECTROMETER

Pure rotational spectra of the isotopomers Ar-(OCO)-O-16-C-13-O-16,Ar- (OCO)-O-17-C-12-O-16 and Ar-(OOO)-O-18-O-12-O-16 of Ar-CO2 have been i nvestigated using a molecular beam Fourier-transform microwave spectro meter. The analyses of the experimental data yielded rotational and ce ntrifugal distortion constants. These data were included in a force fi eld analysis which has resulted in values for van der Waals stretching and bending force constants and harmonic vibration frequencies. In th e case of Ar-(OCO)-O-17-C-12-O-16, hyperfine structure of rotational t ransitions due to the quadrupolar O-17 nucleus was observed and the co rresponding nuclear quadrupole coupling constant could be determined. The obtained data are discussed in terms of structural and dynamical p arameters.