Based on the achievement of synthesis of ZnO nanowires in mass production, ZnO nanowires gas sensors were fabricated with microelectromechanical system technology and ethanol-sensing characteristics were investigated. The sensor exhibited high sensitivity and fast response to ethanol gas at a work temperature of 300 °C. Our results demonstrate the potential application of ZnO nanowires for fabricating highly sensitive gas sensors.

The mechanism of CO 2 dissociation during entry in the Mars atmosphere is experimentally investigated. A hydrogen-oxygen combustion-driven shock tube is used to simulate physical and chemical conditions in a CO 2-N 2 mixture. Two shock velocity/initial pressure conditions are studied: 7.09 0.05 km∕s at 100 Pa (called the low-pressure condition) and 5.68 0.07 km∕s at 300 Pa (called the high-pressure condition). The temperature behind the shock wave is obtained by analyzing the high-temporal-resolution and high-spatial-resolution experimental spectra of the CN violet (B 2 Σ → X 2 Σ , Δv 0) system. The CO number density is derived using a tunable diode laser absorption spectroscopy system based on CO absorption near 2.33 μm. Moreover, a numerical code is developed to reproduce the experimental results (temperatures and species densities). The kinetic code in this work is based on Park's two-temperature model. Comparisons between experiments and calculations are presented. Such a relatively simple two-temperature model fails to accurately describe the nonequilibrium temperature and CO number density but is suitable for equilibrium temperature predictions.

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This work describes a detailed investigation into the magnetic and structural properties of permalloy-tantalum multilayered thin films produced by vacuum evaporation. Their microstructure was investigated using high-resolution TEM and the magnetic properties were measured with vibrating-sample and vibrating-reed magnetometers. The results show a reduction in coercivity for the multilayer films which is independent of the number of layers but depends strongly on the magnetic layer thickness. The tantalum layer is shown to be continuous and microcrystalline down to 25-Å thickness, but the interface between the layers is irregular and may give rise to additional magnetostatic coupling as the tantalum layer thickness is reduced.

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Double layer thin films of permalloy (layer thickness 200-1300 A) with tantalum (50 A) as a nonmagnetic spacer have been prepared by e-beam evaporation. The effec.t of deposition parameters, especially the substrate temperature on the magnetic properties of these films has been examined. The coercivity(I&) of the double layer films was found to be very sensitive to the substrate temperature in the permalloy layer thickness range of 200-600 A. The coercivity of the films deposited at 40 "C is lower than at 300 "C and is almost independent of the Permalloy layer thickness. The XRD patterns and STM images of these two films exhibit large differences in permalloy grain size and grain orientation. However, the He of the single layer films deposited nnder the same conditions as the double layer films shows no significant change in this thickness region. The results indicate that the change of interface condition is primarily responsible for the Ifc variation in the coupled films deposited at different substrate temperatures and strongly suggest t.hat interface roughness plays a dominant role in the coupling between the permalloy layers.