Rotational excitation in D2–CO collisions

Abstract

In a crossed molecular beam experiment total differential cross sections and time of flight distibutions of the scattered particles have been measured for D2+CO at 87.2 meV collision energy. The energy loss spectra, which do not exhibit single rotational transitions, were transformed to the c.m. system so that not only positions but also amplitudes could be compared with calculations. The comparison shows that the spectra are dominated by two rotational rainbow peaks, one at large final rotational states j′ due to the CO excitation on the C side of the molecule and one with larger probability at small j′ due to the excitation on the O side of CO. The positions and the amplitudes of the former peak have been reproduced by the calculation using the ab initio potential [D. R. Flower, J. M. Launay, E. Kochanski, and J. Prissette, Chem. Phys. 37 355 (1979)]; however, the amplitudes of the latter peak are overestimated but can be corrected by a smaller slope of the anisotropy of the potential. The parameters of the fitted isotropic potential ε = 5.73 meV and Rm = 3.88 Å were found to deviate from the prediction. The calculations have been performed by treating D2 in the jz conserving coupled states approximation and CO in the infinite order sudden approximation.