AVS 46th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS2-WeA

Paper SS2-WeA10
Reactive Scattering Dynamics of Fast Atoms with Hydrocarbon Surfaces: Initial and Steady-State Reactions

Wednesday, October 27, 1999, 5:00 pm, Room 607

Session: Gas-Surface Dynamics
Presenter: T.K. Minton, Montana State University
Authors: T.K. Minton, Montana State University
J. Zhang, Montana State University
D.J. Garton, Montana State University
J.W. Seale, Montana State University
Correspondent: Click to Email
The interactions of energetic atoms with hydrocarbon surfaces are largely responsible for the degradation of polymeric materials in space and for the outcome of polymer etch processes. Molecular beam-surface scattering experiments show that non-equilibrium processes dominate both the initial and steady-state interactions when a hydrocarbon surface is bombarded with a beam containing fast oxygen atoms. Direct inelastic scattering is the most probable non-reactive interaction. The most likely initial interaction is gas-phase-like H-atom abstraction to form OH. Once formed, the OH may undergo further collisions and reactions with the surface, some of which produce H@sub 2@O. The initial reactive and non-reactive events may be described with a simple kinematic picture that allows us to determine the effective surface mass encountered by an incident O atom, as well as the fraction of the atom-surface collision energy (in the center-of-mass frame) that is converted into internal energy in the surface and in the recoiling gaseous species. During steady-state oxidation, CO and CO@sub 2@ are produced. Formation of these molecules is believed to account for the erosion, or mass loss, of a polymer under O-atom attack. The rate of CO and CO@sub 2@ production from the surface is significantly enhanced when high-energy (>9 eV) Ar atoms collide with a surface that is undergoing continuous oxidation. This observation suggests that collisional processes may be important in material etching.