Nuclear quadrupole hyperfine structure in the microwave spectrum of Ar-N2O

Nuclear quadrupole hyperfine structure in the rotational spectrum of Ar-N2O has been resolved in the 7-18 GHz region using a Fourier transform microwave spectrometer. Analysis of the hyperfine lines enables not only the determination of the rotational and centrifugal distortion constants to greater precision than previous studies, but also provides values for the nuclear quadrupole coupling constants of each N-14 nucleus. The coupling constants for Ar-N2O, when compared to those for free N2O, show that the electric field gradient at the terminal nitrogen nucleus in the N2O subunit is not affected by the presence of Ar, whereas that at the central nitrogen nucleus is affected slightly. This result, in contrast to recent findings in HCCH-N2O, supports the usual practice of extracting geometrical information for a van der Waals molecule from the nuclear quadrupole coupling tensor(s) of the complex. (C) 1997 Academic Press.