Dielectric barrier discharges are used to generate ultraviolet radiation in rare gases and rare gas-halide mixtures. The characteristics of the emission spectra of the excimers formed, from 126 to above 308 nm are found to be useful for thin film and surface processing. The underlying radiation generation mechanisms are described and the influence of gas mixture, concentration and total pressure on the UV emitted discussed. Conversion efficiencies (from input electrical to output optical energy) as high as 15% can be achieved under optimum conditions. These low cost, high power excimer systems can provide an interesting and potentially very useful alternative to conventional UV lamps for industrial large-scale low temperature processes.