Capacitance spectroscopic study of the Si/HF-electrolyte interface

Thep-Si/HF-electrolyte interface was characterized by capacitance–voltage (C–V) and current–voltage (I–V) studies. At low frequency, the measured capacitance exhibits two maxima: one in the weak accumulation regime (around 0.8 V [SCE]) and the other in the strong accumulation regime (around 2.6 V [SCE]), both of which disappear at high frequency. The disappearance of the two capacitance maxima is attributed to the slow response of interface traps to high frequencies. The flat-band potential, V_FB, is found to be frequency dependent. The surface state densities corresponding to the two capacitance maxima are estimated to be 3.2×10¹¹ cm^-2 and 2.4×10¹¹ cm^-2, respectively. The in situ I–V characteristics distinguish pore formation, transition and electropolishing regions. Porous Si synthesized at 50 mA cm^-2 gives a broad photoluminescence peak around 2.04 eV at 300 K. Received: 4 September 2000 / Accepted: 9 February 2001 / Published online: 26 April 2001     

Polyethers from 5,5′-methylene-bis (8-hydroxyquinoline)

Polyethers have been prepared by condensing the disodium salt of 5,5′-methylene-bis(8-hydroxyquinoline) (MBQ) with p-xylylene dichloride and dibromide, 4,4′-dichloromethyldiphenyl ether, 4,4′-dichloroacetyldiphenyl, 4,4′-dichloroacetyldiphenyl ether and methylene and ethylene dichlorides. All the polycondensations except those with the two aliphatic dihalides could be effected in dioxane and in DMF. The polycondensation of the disodium salt of MBQ with the two aliphatic dihalides could be effected in the absence of solvent in a sealed tube using Ullman catalysts. All the polyethers are insoluble in common organic solvents. I.R. spectra of the polyethers have been measured in KBr. The thermal and electrical properties of these polyethers have been studied.     

Atomic absorption spectrometric studies of the atomization of boron from a carbon rod atomizer

Boron (<20 μg ml^?1) in aqueous solutions gives no absorbance but addition of ascorbic acid, especially with titanium greatly enhances the signal, leading to a detection limit of 0.2 μg ml^?1 boron. The presence of uranium (<10 mg ml^?) only slightly decreases the boron signal.     

Chou-Yang model and predictions for high-energy pion-deuteron scattering

Using fits to the available data on the pion and deuteron electromagnetic form factors and the Chou-Yang model, the computed values of differential cross-sections for high-energy pion-deuteron elastic scattering agree reasonably well with the available experimental data. Whereas only a shoulder is expected to appear up to energies of several hundreds of GeV, a dip and a secondary maximum are predicted to be conspicuous only forP _lab≫400 GeV/C. The position of the dip starts at a much lower value, |t _d| ≅ 0.5–0.6 GeV², as compared to the corresponding position in thepp scattering. The positions of the first dip are plotted against total cross-section which can be verified by future high-energy experiments. Limitations of the model predictions for ultrahigh energies are pointed out.     

Comparative behavior of electrodes coated with thin films of structurally related electroactive polymers

General methods are described for the synthesis of electroactive polymers and the preparation of uniform, stable, polymer-coated electrodes. The electrochemical behaviour of thin films of eight different functionalized polystyrenes, differing in the identity and amount of attached electroactive species, and polyvinylferrocene is presented. A wide range of electrochemical properties can be observed by varying parameters such as film thickness, nature of the bound redox couple, extent of polymer functionalization and oxidation state. The deviations from ideal surface behavior are investigated in detail. These are shown to be consequences of cooperative electronic interactions, structural reorganization or uncompensated resistance within the film, depending upon the material. The film resistance varies greatly among the polymer films studied and is shown, in some cases, to be a sensitive function of the extent of oxidation and prior treatment of the film. This variable resistance is shown to be a consequence of slow ion transport through the film. The mechanism of electron transport in such materials is considered and a model of the metal/polymer/electrolyte interface is proposed.     

A NUT-like electrovac spacetime

A solution of the Einstein-Maxwell equations corresponding to source-free electromagnetic field is obtained. The solution is algebraically special. A particular case of the solution is considered which includes Brill’s solution. The details regarding the solution are also discussed.     

Hype and Reality in the Future Home

What will stay the same and what will change in homes of the future? This paper tracks and analyses various streams of thought, past and present, looking ahead to emerging technologies which extend and develop our thinking on what might be core to the future home.