An ultraviolet spectrometer based on attenuated total reflection (ATR) has been developed and tested for liquid water (light and heavy water) in the wavelength range from 140 to 300 nm, which includes the far ultraviolet (FUV) region. One of the principal limitations of FUV transmission spectra is the strong absorption of the solvent itself. High absorptivity of the n --> sigma(*) transition in water molecule has thus far prevented meaningful spectral measurements of aqueous solutions in the wavelength region under 170 nm. Our technique uses the evanescent wave created through total reflection when light is passed through an internal reflection element (IRE) in contact with the sample. Since the evanescent field is used as an optical path length, the method allows spectral measurements favorably comparable with that of transmittance method with a shorter path length than the wavelength of FUV light. In this study, we have designed an original miniature IRE probe made of sapphire that allows detection of the whole n --> sigma(*) transition absorption band of water down to 140 nm. The obtained ATR-FUV spectra closely match calculations based on the Fresnel formula. It is also confirmed that this spectrometer is equally effective for spectral measurements of nonaqueous solvents with significant absorptivities in the FUV region. 相似文献
Although high carrier mobility organic field‐effect transistors (OFETs) are required for high‐speed device applications, improving the carrier mobility alone does not lead to high‐speed operation. Because the cut‐off frequency is determined predominantly by the total resistance and parasitic capacitance of a transistor, it is necessary to miniaturize OFETs while reducing these factors. Depositing a dopant layer only at the metal/semiconductor interface is an effective technique to reduce the contact resistance. However, fine‐patterning techniques for a dopant layer are still challenging especially for a top‐contact solution‐processed OFET geometry because organic semiconductors are vulnerable to chemical damage by solvents. In this work, high‐resolution, damage‐free patterning of a dopant layer is developed to fabricate short‐channel OFETs with a dopant interlayer inserted at the contacts. The fabricated OFETs exhibit high mobility exceeding 10 cm2 V?1 s?1 together with a reasonably low contact resistance, allowing for high frequency operation at 38 MHz. In addition, a diode‐connected OFET shows a rectifying capability of up to 78 MHz at an applied voltage of 5 V. This shows that an OFET can respond to the very high frequency band, which is beneficial for long‐distance wireless communication. 相似文献
Niobium oxide films were prepared over a quartz plate by withdrawing it from a solution of niobium penta-isopropoxide (NIP) dissolved in sec-propyl alcohol. The films calcined at 673 K were well controlled in the film thickness either by NIP concentration in the solution or by the withdrawing rate of the quartz plate from the solution. BET surface area of the calcined films was as huge as around 400 m2g−1 and was not reduced by cyclic adsorption/desorption of water vapor. A rapid decrease and increase in the electrical resistivity of the calcined films was well associated with the cyclic adsorption/desorption of water vapor. The decrease in the electrical resistivity of the films by water vapor adsorption was more than 10 times sensitive than the decrease caused by the adsorption of ethanol, hydrocarbons, carbon monoxide and carbon dioxide. These results suggest an application of the niobium oxide films as an element of a humidity sensor.
The calcined films were proved by SEM observation to consist of tiny particles possessing a lotofmicropores sized less than 20 A. The decrease in the electrical resistivity of the films, or the increase in the electrical conductivity, was attributed to the water vapor adsorbed in these micropores. In order to identify the charge carriers during water vapor adsorption on the films, changes in the impedance and the phase shift caused by water vapor adsorption were measured using an LCR meter in AC frequency range of 10 Hz to 100 kHz. From a complex impedance plotting, single semicircule was obtained for water vapor adsorption onto the films, suggesting single adsorbed species as a charge carrier. Assuming an equivalent electric circuit for the films adsorbing water vapor, a constant capacitance was calculated under various partial pressures of water vapor, probably suggesting that the charge carriers will be H3O+ on the films. 相似文献
Abstract— We have developed highly resolved spatio‐temporal optical emission spectroscopy to investigate the discharge characteristics of coplanar type ac plasma‐display panels (AC‐PDPs). Spatio‐temporal emission profiles were measured for relevant lines of atomic He, Ne, Xe, and ionic Xe in He‐Xe and Ne‐Xe systems with various Xe concentrations and total gas pressures. The surface‐discharge behavior in coplanar PDPs has been clarified. 相似文献
A combination of chemical vapour deposition (CVD) and high-pressure (HP) techniques has achieved the fabrication of the zincblende form of boron nitride (z-BN)-based ceramic composites. The CVD technique provides amorphous B-N-X (X = aluminium, silicon or titanium). The HP technique renders the amorphous samples crystalline and decomposition into z-BN plus the respective nitride (-Si3N4 for instance) occurs. Compacts of the composites are obtained byin situ sintering under high pressure. The compacts exhibit peculiar microstructures composed of z-BN nano-crystals homogeneously dispersed in the nitride matrices. 相似文献
The aim of the present study is to propose a totally new technique for the utilization of far-ultraviolet (UV) spectroscopy in polymer thin film analysis. Far-UV spectra in the 120-300 nm region have been measured in situ for six kinds of commercial polymer wrap films by use of a novel type of far-UV spectrometer that does not need vacuum evaporation. These films can be straightforwardly classified into three groups, polyethylene (PE) films, polyvinyl chloride (PVC) films, and polyvinylidene chloride (PVDC) films, by using the raw spectra. The differences in the wavelength of the absorption band due to the sigma-sigma* transition of the C-C bond have been used for the classification of the six kinds of films. Using this method, it was easy to distinguish the three kinds of PE films and to separate the two kinds of PVDC films. Compared with other spectroscopic methods, the advantages of this technique include nondestructive analysis, easy spectral measurement, high sensitivity, and simple spectral analysis. The present study has demonstrated that far-UV spectroscopy is a very promising technique for polymer film analysis. 相似文献
The decomposition of benzene in air was carried out using a nonthermal plasma discharge reactor packed with ferroelectric materials. It was found that ferroelectric materials of 1-2 mm in diameter with a relative dielectric constant of ϵr>1100 decomposed benzene with greatest energy efficiency. Benzene at low concentrations (below 50 ppm) was completely decomposed to CO and CO2 with no formation of other hydrocarbons. The ratio of CO to CO2 produced from benzene was minimized under an atmosphere containing more than 5% O2相似文献
We implemented 72-Mb direct Rambus DRAM with new memory architecture suitable for multibank. There are two novel schemes: flexible mapping redundancy (FMR) technique and additional refresh scheme. This paper shows that multibank reduces redundancy area efficiency. But with the FMR technique, this 16-bank DRAM realizes the same area efficiency as a single-bank DRAM. In other words, FMR reduces chip area by 13%. This paper also describes that additional refresh scheme reduces data retention power to 1/4. Its area efficiency is about four times better than that of the conventional redundancy approach 相似文献