Microwave Spectra of the Ar-ND3 van der Waals Complex and Its Partially Protonated Isotopomers.
Jennifer van Wijngaarden and Wolfgang Jäger
Rotational spectra of the Ar-ND3 van der Waals complex were measured in the frequency range between 4 and 19 GHz using a pulsed jet cavity Fourier transform microwave spectrometer. The isotopomers studied included those of ND3, NHD2 and NH2D. a tunnelling splitting due to the inversion of the ammonia subunit within the ground state of the complex was observed for all three isotopomers. Nuclear quadrupole hyperfine structure arising from the 14N nucleus was resolved and the corresponding nuclear quadrupole coupling constants were determined. a smaller nuclear quadrupole splitting arising from D was observed but not resolved. The ground state spectroscopic constants were compared with experimental and theoretical data previously reported for Ar-NH3. Additional transitions for Ar-ND3 were observed and assigned to the two inversion tunnelling states of an excited internal rotor state. a fit of the spectroscopic constants for these two states suggested the presence of a Coriolis perturbation along the lines of that observed in the microwave spectrum of Ar-NH3.