A new millimeter-wave observation of the weakly bound CO-N2 complex

New millimeter-wave transitions of the CO-N-2 van der Waals complex have been observed using the intracavity OROTRON jet spectrometer in the frequency range of 103-159 GHz. For the less abundant form, CO-paraN(2), a total of 37 rotational transitions were assigned to three K = 0-0, 0-1, 2-1 subbands connecting the (j(co), j(N2))= (1,1) and (j(co), j(N2)) = (0,1) internal rotor states. The upper K = 0 and K = 2 "stacks" of rotational levels were probed for the first time here by millimeter-wave spectroscopy following a recent infrared study by Rezaei et al. (2013). The observation of new subbands fixes with higher precision not only these upper K = 0 and K = 2 but also lower K= 1(f) levels, not linked with other stacks in earlier rotational studies. For the more abundant form, CO-orthoN(2), five new P-branch rotational transitions of the K = 0-0 "CO bending" subband are reported, thus extending previous measurements. Nuclear quadrupole hyperfine structure due to the presence of two equivalent N-14 nuclei was partly resolved and analyzed to give additional information about the angular orientation of the N-2 molecule in the complex. (C) 2014 Elsevier Inc. All rights reserved.