Microwave spectra of the Xe-N_2 van der Waals complex: A comparison of experiment and theory

摘要

Rotational transitions for the Xe-N_2 complex were measured in the frequency region from 4 to 18 GHz using a pulsed-nozzle Fourier-transform microwave spectrometer.Twelve (four)a-type transitions were recorded for the ~(132)Xe-~(14)N_2 and ~(129)Xe-~(14)N_2 (~(131)Xe-~(15)N_2) isotopomers.Inaddition,the nuclear quadrupole hyperfine structures due to the presence of the ~(14)N (nuclear-spin quantum number I=1) and ~(131)Xe (I=3/2) nuclei were detected and analyzed.Two ab initio potential-energy surfaces were calculated at the coupled-cluster level of theory with single,double,and pertubatively included triple excitations.Dunning's augmented correlation-consistent polarized valence triple-zeta basis set was used for the nitrogen atoms.For the first surface,a well-tempered basis set with additional polarization functions was used for the Xe atom;for the second surface,a newly developed augmented correlation-consistent polarized valence quintuple-zeta basis set employing small-core relativistic pseudopotentials was used for the Xe atom.The basis sets weresupplemented with bond functions for the van der Waals ond.The counterpoise correction was applied to reduce the basis-set superposition error.The resulting two surfaces both have a single minimum at a T-shaped geometry,with well depths of 122.4 and 119.3cm~(-1),respectively.Bound-state energies supported by the potential-energy surface were determined.The quality of the ab initio potential-energy surfaces was evaluated by comparison of the experimental transition frequencies and rotational and centrifugal istortion constants with those derived from the bound-state energies.A scaled potential-energy surface was obtained which has excellent agreement with the experimental data.