Pure rotational spectrum of, and potential-energy surface for, the Ar–N2 Van der Waals complex

Pure rotational spectra of three isotopomers of the Van der Waals complex Ar–N2 have been investigated in the frequency range 3.5–20 GHz, using a pulsed molecular beam cavity microwave Fourier-transform spectrometer. Rotational constants and quartic and sextic centrifugal distortion constants have been obtained, along with N hyperfine constants. The spectra of Ar–14N2 and Ar–15N2 indicate equivalence of the nitrogen nuclei, and thus confirm C2v symmetry for the complexes. The measured transition frequencies and the derived constants have been used to test the best available literature potential-energy surfaces for the Ar–N2 interaction. For this purpose rotational transition frequencies and expectation values of other properties were calculated and compared with the corresponding values from the microwave experiments. A refined version of one of the surfaces has been generated by inclusion of the microwave results.