Collisional excitation of H-2 by grains in C-type shocks

We have performed classical trajectory Monte Carlo calculations of the prob abilities of rovibrational excitation and dissociation of molecular hydroge n in collisions with a surface, modelled as MgO. The results show that, in C-type shock waves, states of high excitation energy are populated predomin antly in collisions with charged grains, rather than with much more abundan t neutral species. The intensities of rovibrational transitions of H-2 have been calculated for a series of models of C-type shocks, considered to be relevant to molecular outflow sources. We compare the column densities of e xcited states of H-2 and the intensities of representative rovibrational tr ansitions, calculated excluding and including collisions with grains.