Rovibrational spectra and molecular structure of SF6-CO van der Waals complex

The rovibrational spectra of SF6-CO van der Waals complex have been measured in the v3 region of SF6 and the CO fundamental region by direct absorption of quantum cascade laser in a pinhole supersonic jet expansion. The observed rovibrational transitions for SF6-CO complex are analysed using a standard symmetric top Hamiltonian, yielding precise molecular constants for the ground and excited vibrational states. The band origins of SF6-CO complex are determined to be 947.29232(98) and 946.84794(69) cm−1 for the perpendicular and parallel bands in the v3 region of SF6, and 2144.52605(116) cm−1 in the fundamental region of CO, respectively. The possible stable structures of the complex are searched at the MP2 and B3LYP-D3(BJ) level of theory. The differences of interaction energies of the three lowest-energy structures calculated at the CCSD(T)/aug-cc-pVTZ level of theory are less than 30 cm−1.