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

Abstract

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 C_2v 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.