Stereodynamic Effects of CO Molecules Scattered from a Graphite Surface

The scattering of CO molecules from a graphite surface has been characterized by
exploiting molecular dynamics simulations, based on a chemical state-to-state semiclassical collisional
method, and adopting a new reactive potential energy surface that considers the proper treatment of
long-range noncovalent interactions promoting the physisorption. Carbon monoxide molecules impinge
the surface in well-defined initial rotovibrational states and with the collision energy varying from
subthermal up to hyperthermal values. The simulations predict that scattering events occur through
both single- and multi-bounces and the initial vibrational state is preserved. In the multibounces
instance, molecules tend to be trapped in the physisorption well, especially for collision energies lower
than the thermal one. For medium-high collision energies, the scattering occurs mainly via a singlebounce
mechanism. The heteronuclear character of the molecule brings out a new intriguing
stereodynamic effect, in addition to those highlighted for homonuclear molecules: due to the
anisotropic physisorption attraction, the molecule C-end bends toward the surface while approaching
this latter. This effect produces evident propensities in the final rotational distributions of the CO
scattered molecules.