Pure rotational spectrum of, and potential-energy surface for, the Ar–N₂Van der Waals complex

Abstract

Pure rotational spectra of three isotopomers of the Van der Waals complex Ar-N, 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-I4N, and Ar-"N, indicate equivalence of the nitrogen nuclei, and thus confirm C,, 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-N, 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.

N2–Kr interaction: A multiproperty analysis

“…19 It has also been established recently 25 that the positions of the centers of gravity of the experimentally observed MW hyperfine transitions provide a sensitive probe of R m (␥). Thus, since a calculation of the centers of gravity of the MW lines associated with the N 2 -Kr complex based upon the original Rotzoll potential surface already gives considerably better agreement with the MW data than do calculations based upon the other model surfaces mentioned above, it was decided to modify the Rotzoll potential surface to bring the calculated temperature dependence of the interaction second virial coefficient and the MW spectrum of the van der Waals complex into agreement with experiment.…”

“…25. At the fitting stage the only JЉ→JЈ MW transitions utilized were those corresponding to (JЉ,JЈ)ϭ(1,2) and ͑2,3͒ for each of the ⌺ e (0), ⌸ f (1), ⌸ e (1) sequences of pure rotational lines for the 14 N 2 -86 Kr van der Waals complex.…”

“…Measurements of the first four properties, together with the total differential and integral scattering cross-section measurements, have often been employed to establish a reasonably refined isotropic component of the interaction potential surface, together with first estimates of the anisotropy of the well position and well depth. The microwave spectrum of the van der Waals complex can then be used to fine tune the position of the minimum, 25 while rotational state-to-state differential cross sections ͑if available͒, the external field effects on the transport phenomena and nuclear magnetic relaxation times can be utilized to fine tune the anisotropy on the repulsive wall and at the potential minimum. The infrared spectrum of the van der Waals complex and the collision broadening and shifting of the spectroscopic lines can then be used to check the overall potential.…”

Interaction of N2 with Kr: Potential energy surface and bound states

“…In the past several decades, a lot of attention was attracted on the interaction of rare gases with the N 2 molecule in experimental [1][2][3][4][5][6] and theoretical [7][8][9][10][11] studies. For example, high-resolution microwave spectra of the ground state 20 Ne-14 N 2 , 20 Ne-15 N 2 , 22 Ne-14 N 2 , and 22 Ne-15 N 2 Van der Waals complexes, involving rotational levels up to J = 4, were reported by Jäger et al [1] in 1998.…”

“…The first IR spectrum of the Ar-N 2 complex was observed by Henderson and Ewing [2] in 1974. The microwave spectrum of the complex was recorded by Jäger and Gerry [3] in 1992, and refined by Jäger et al [4] in 1994. In the frequency ranged from 3.5 to 24 GHz, it showed two equivalent nitrogen nuclei, and therefore a T-shape structure for the complex.…”