Measurement of theKa= 1 (vco= 1)stretching mode in Ar—CO using a Herriott multipass cell

Rovibrational structure of the Xe-CO complex based on a new three-dimensional ab initio potential

The first three-dimensional interaction potential energy surface of the Xe-CO complex is developed using the single and double excitation coupled cluster theory with noniterative treatment of triple excitations. Mixed basis sets, aug-cc-pVQZ for the C and O atoms and aug-cc-pVQZ-PP for the Xe atom, including an additional (3s3p2d2f1g) set of midbond functions are used. The calculated single point energies at five fixed r(co) values are fitted to an analytic two-dimensional potential model, and further the five model potentials are used to construct the three-dimensional potential energy surface by interpolating along (r-r(e)). Dynamical calculations with the vibrationally averaged potentials are performed to determine the energy levels and the frequencies of various rovibrational transitions. Our results agree well with the experiment. For example, the IR transitions of 508 lines are precisely reproduced with only a total rms error of 0.105 cm(-1).

The potential energy surface of the Ar-CO complex obtained using high-resolution data

A potential energy surface is retrieved for the Ar-CO complex by carrying out a global analysis of its high-resolution spectroscopic data. The data set consists of already published microwave and infrared data and of new microwave transitions which are presented in the paper. The theoretical approach used to reproduce the spectrum is based on a model Hamiltonian which accounts simultaneously for the two large amplitude van der Waals modes and for the overall rotation of the complex. Only the vCO = 0 state is considered. The root-mean-square deviation of the analysis is 18 MHz for the microwave data and 1.4 x 10(-3) cm(-1) for the infrared energy difference data. Fifteen parameters corresponding to the potential energy function are determined in addition to two kinetic energy parameters and two distortion-type parameters. The potential energy surface derived is in good agreement with the one obtained by Shin, Shin, and Tao [J. Chem. Phys. 104, 183 (1996)].