Rotationally resolved infrared spectrum of the Li+-D-2 cation complex

摘要

The infrared spectrum of mass selected Li+-D-2 cations is recorded in the D-D stretch region (2860-2950 cm(-1)) in a tandem mass spectrometer by monitoring Li+ photofragments. The D-D stretch vibration of Li+-D-2 is shifted by -79 cm(-1) from that of the free D-2 molecule indicating that the vibrational excitation of the D-2 subunit strengthens the effective Li+center dot D-2 intermolecular interaction. Around 100 rovibrational transitions, belonging to parallel K-a=0-0, 1-1, and 2-2 subbands, are fitted to a Watson A-reduced Hamiltonian to yield effective molecular parameters. The infrared spectrum shows that the complex consists of a Li+ ion attached to a slightly perturbed D-2 molecule with a T-shaped equilibrium configuration and a 2.035 A vibrationally averaged intermolecular separation. Comparisons are made between the spectroscopic data and data obtained from rovibrational calculations using a recent three dimensional Li+-D-2 potential energy surface [R. Martinazzo, G. Tantardini, E. Bodo, and F. Gianturco, J. Chem. Phys. 119, 11241 (2003)]. (c) 2006 American Institute of Physics.