We consider the negative ion concentrations in hydrogen discharges caused by electron excitation and dissociative attachment processes. The principal formation and destruction processes are discussed for electron densities in the range 10/sup 8/ to 10/sup 13/ electrons cm/sup -3/. Expressions are developed for calculating the high energy portion of the electron energy distribution in the discharge; using these energy distributions the electron excitation rates are evaluated. At low densities, the vibrational distribution arises from singlet electronic excitations and triplet excitations through the /sup 3/..pi../sub u/ state, in equilibrium with wall de-excitation processes. At high densities singlet excitations predominate in equilibrium with atom-molecule de-excitation processes. Possibilities for negative ion generation in a two-chamber tandem system are discussed in which the vibrational excitation occurs in a high power, high electron temperature discharge, kT/sub e/ = 5 eV, and dissociative attachment occurs in a low temperature kT/sub e/ = 1 eV, plasma chamber.

Angle integrated and angle resolved ultraviolet photoelectron spectroscopy (UPS and ARPES) and high resolution electron energy loss spectroscopy (HREELS) have been performed on the low index single crystal surfaces of zinc oxide. Study of CO/ZnO shows that the mode of binding is dominated by 5sigma donation from the carbon end of the molecule to the unsaturated surface zinc ion with little ..pi.. backbonding to the CO2..pi..* orbital. This electronic structure is verified by a HREELS study. The geometry of CO binding is consistent with LEED studies where no symmetry changing reconstructions are observed to occur, and where the CO molecule forms an approximately linear Zn-C-O surface complex along the coordinatively unsaturated directions of the surface zinc ions. Implications of these studies to the mechanism of methanol synthesis is described. These UPS studies have also provided insight into the bonding interaction between small molecules such as NH/sub 3/ and CO/sub 2/ (as well as H/sub 2/O, C/sub 2/H/sub 4/, CH/sub 3/OH, H/sub 2/S and CH/sub 3/SH) and the ZnO single crystal surfaces.