title: Rotational study of the NH3-CO complex: millimeter-wave measurements and ab initio calculations.
abstract: The rotational spectrum of the van der Waals complex NH3-CO has been measured with the intracavity OROTRON jet spectrometer in the frequency range of 112-139 GHz. Newly observed and assigned transitions belong to the K = 0-0, K = 1-1, K = 1-0, and K = 2-1 subbands correlating with the rotationless (jk)NH3 = 00 ground state of free ortho-NH3 and the K = 0-1 and K = 2-1 subbands correlating with the (jk)NH3 = 11 ground state of free para-NH3. The (approximate) quantum number K is the projection of the total angular momentum J on the intermolecular axis. Some of these transitions are continuations to higher J values of transition series observed previously [C. Xia et al., Mol. Phys. 99, 643 (2001)], the other transitions constitute newly detected subbands. The new data were analyzed together with the known millimeter-wave and microwave transitions in order to determine the molecular parameters of the ortho-NH3-CO and para-NH3-CO complexes. Accompanying ab initio calculations of the intermolecular potential energy surface (PES) of NH3-CO has been carried out at the explicitly correlated coupled cluster level of theory with single, double, and perturbative triple excitations and an augmented correlation-consistent triple zeta basis set. The global minimum of the five-dimensional PES corresponds to an approximately T-shaped structure with the N atom closest to the CO subunit and binding energy De = 359.21 cm(-1). The bound rovibrational levels of the NH3-CO complex were calculated for total angular momentum J = 0-6 on this intermolecular potential surface and compared with the experimental results. The calculated dissociation energies D0 are 210.43 and 218.66 cm(-1) for ortho-NH3-CO and para-NH3-CO, respectively.
authors: I. Physikalisches Institut, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany.
authors: L A
authors: LA
authors: Surin
authors: I. Physikalisches Institut, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany.
authors: A
authors: A
authors: Potapov
authors: Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 142190 Troitsk, Moscow, Russia.
authors: A A
authors: AA
authors: Dolgov
authors: Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 142190 Troitsk, Moscow, Russia.
authors: I V
authors: IV
authors: Tarabukin
authors: Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya Str. 5, 142190 Troitsk, Moscow, Russia.
authors: V A
authors: VA
authors: Panfilov
authors: I. Physikalisches Institut, University of Cologne, Zülpicher Str. 77, 50937 Cologne, Germany.
authors: S
authors: S
authors: Schlemmer
authors: Department of Optics and Spectroscopy, Tomsk State University, 36 Lenin av., 634050 Tomsk, Russia.
authors: Y N
authors: YN
authors: Kalugina
authors: Université de Grenoble Alpes, IPAG, F-38000 Grenoble, France.
authors: A
authors: A
authors: Faure
authors: Theoretical Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors: A
authors: A
authors: van der Avoird