SCATTERING OF SWIFT DIATOMIC MOLECULAR-IONS FROM PLANAR SURFACES AT GRAZING-INCIDENCE

Grazing-incidence scattering of Coulomb-exploding fragments of a diato mic molecule from a surface has been analysed by molecular-dynamics si mulation. The influence of a number of input parameters on the compute d emergence pattern has been studied. Trajectories are strongly affect ed by Coulomb explosion, and the dominating parameter is the initial o rientation of the impinging molecule. Other parameters analysed, in th e order of decreasing significance, include position-dependent electro nic stopping, electrostatic image,force, internuclear distance, surfac e potential, the distance at which Coulomb explosion sets in, and elec tronic or nuclear multiple scattering. Only two-dimensional trajectori es have been studied. Computed peak energies versus scattering angle a gree well with experimental results for 400 keV H-2+ on W surfaces, wh ile computed spectra are much narrower than found experimentally.