Recent advances in the development of microplasma devices fabricated in a variety of materials systems (Si, ceramic multilayers, and metal/polymer structures) and configurations are reviewed. Arrays of microplasma emitters, having inverted pyramidal Si electrodes or produced in ceramic multilayer sandwiches with integrated ballasting for each pixel, have been demonstrated and arrays as large as 30×30 pixels are described. A new class of photodetectors, hybrid semiconductor/microplasma devices, is shown to exhibit photoresponsivities in the visible and near-infrared that are more than an order of magnitude larger than those typical of semiconductor avalanche photodiodes. Microdischarge devices having refractory or piezoelectric dielectric films such as Al 2 O 3 or BN have extended lifetimes (∼86% of initial radiant output after 100 h with an Al 2 O 3 dielectric) and controllable electrical characteristics. A segmented, linear array of microdischarges, fabricated in a ceramic multilayer structure and having an active length of ∼1 cm and a clear aperture of 80 × 360 µm 2 , exhibits evidence of gain on the 460.3 nm transition of Xe + , making it the first example of a microdischarge-driven optical amplifier.

No abstract

The emission spectra of XeBr, XeCl, XeF, and KrF at high pressure are reported and discussed. The spectra were obtained by observing spontaneous emission from electron beam excited mixtures of argon containing lesser amounts of xenon with the halogens or krypton with fluorine. The emitting state in these species is best described as an ionic species Xe+X− or Kr+F−. The wavelengths of these emission bands are in good agreement with a theoretical model in which the ionic binding energy of the noble gas halide ion pair is roughly equal to that of the nearest alkali halide. Our high pressure spectra imply that the lowest potential energy curve for XeF is bound.

No abstract

The primary dissociation step for alkali halide diatomics in argon has been studied in order to determine whether collisional dissociation produces ions, atoms, or a mixture of both types of products. The method is based on time-resolved absorption spectroscopy of shock-heated vapors. Results show that the cesium halides, and the rubidium and potassium halides, with the exception of the two iodides, dissociate essentially completely to ions; that the lithium salts and NaI and NaBr dissociate essentially completely to atoms; and that the other alkali halides (KI, RbI, NaCl, and probably NaF) dissociate to mixtures of atoms and ions, at least under some conditions. The branching ratio of atom pairs/ion pairs is interpreted in terms of the effective width of the adiabatic dissociation channel, compared with the spacing of the vibrational levels of the diabatic bound state.