Collision induced processes at the gas-surface interface

The collision of energetic gas phase particles with adsorbed species can induce a variety of processes. Events of this kind can play an important role in the mechanisms governing heterogeneous catalysis at high pressures and elevated temperatures. Two collision induced processes (CIP) are described in this article. The first process discussed is collision induced desorption (CID). The CID of N₂ from Ru(001) is considered at both low and high coverage ranges. The interpretation of the experimental data using molecular dynamics (MD) simulations leads to the introduction of a new desorption mechanism involving surface corrugation and adsorbate frustrated rotational motion. The second process is collision induced migration (CIM), an event that has never been considered before neither experimentally nor theoretically. It is demonstrated, using MD simulations, that following energetic CIM, very long distances of more than 100Å can be covered by the adsorbates at low coverages. At high coverages, on the otherhand, these displacements become considerably shorter due to surface collisions with neighbors.