Vibrational excitation in H+--H2 collisions. Comparison between experiment and rotationally sudden impact parameter calculations

Differential cross section measurements are reported for vibrational excitation in H+--H2 collisions at E/sub c. m./=15.3 eV and 20 eV and for scattering angles including the rainbow region. The experimental results are compared with theory using an impact parameter approach. Rotational motion is treated in the sudden approximation, whereas the Schroedinger equation for vibrational excitation under the action of the time-dependent force is solved exactly using the Giese and Gentry fit potential surface. Very good agreement is found between theory and experiment indicating that the impact parameter approach is applicable for energies down to E/sub c. m./=15 eV and for angles up to theta/sub c. m./=20degree