W. Lester S. Andrews of the University of Virginia is supported by the Experimental Physical Chemistry Program to continue his matrix-isolation Fourier Transform Infrared studies of reactive species. In previous work, laser ablation was used to generate hot atoms which subsequently reacted at or near the matrix to form the species of interest. In this award, the emphasis is on a) understanding the laser ablation process itself and b) pursuing new chemical applications. In the former case, e.g., the PI will investigate the source for the activation energy of the reaction in which laser ablated Fe reacts with O2 to form OFeO, a reaction that does not occur thermally. Is the activation energy due to excess kinetic energy, electronic excitation involving metastables or radiation from the laser plasma? Additions to the apparatus involving magnetic or electric fields will allow manipulation of charged species, which should lead to an understanding of some of the underlying mechanisms. Laser ablation experiments with beryllium and oxygen in a neon matrix will be carried out in an attempt to isolate the first neutral neon compound NeBeO. Finally, the isolation of reaction intermediates in semiconductor growth processes will be attempted. Given current interest in pulsed laser ablation to grow semiconductor thin films, reactions of GaAs, GaP and InSb with H2 will be emphasized. Density functional theoretical studies will be done in collaboration with Bauschlicher, although the emphasis in this proposal is on the experimental aspects. Pulsed-laser ablation is rapidly becoming an extremely important physical technique and is currently employed in such diverse areas as plasma physics, analytical chemistry and the growth of superconductors. Better understanding of the laser ablation process would help foster further applications of this technology.
