Wayne Rabalais

Surface science; surface reactions and catalysis; ion beams; ion beam modification of surfaces; ion beam film deposition; ion scattering and recoiling spectrometry and imaging; x-ray photoelectron spectrometry; Auger electron spectrometry, low energy electron diffraction; secondary ion mass spectrometry.

Research is being carried out in two general areas:

(1) Development and use of time-of-flight scattering and recoiling spectrometry (TOF-SARS) and scattering and recoiling imaging spectrometry (SARIS) as real-space surface crystallographic techniques. Recent developments have led to a surface crystallography that is sensitive to all elements, including hydrogen. TOF techniques for the detection of atoms scattered and recoiled from surfaces in simple collision sequences, along with trajectory simulations, are used to measure surface atomic positions to an accuracy of < 0.1 Å. Such surface and adsorption site determinations have application in catalysis, thin film growth, and interfaces.

(2) Low energy (< 500 eV) reactive ion beams are being used for surface modification and film deposition. The mechanism of deposition and growth of artificially structured materials within the non-equilibrium environment of low energy ion beams is being investigated. Pulsed ion beams are used to control film stoichiometry and to grow structures on a nanometer scale. The subplantation nature of the growth mechanism allows for formation of unique materials, metastable solids, and low temperature epitaxy.

Current research projects include studies of hydrogen on surfaces, surface reconstruction and composition of metal oxides, ion-surface electron exchange probabilities, effects of semiconductor doping on scattered ion fractions, radiation enhanced diffusion (RED) in metal oxides, chemical effects in RED, isotopic structuring of thin films, and controling the optical, electrical, and mechanical properties of oxides through selective ion irradiation.