A plasma sputtering decoration route to producing thickness-tunable ZnO/TiO2 core/shell nanorod arrays

We report a radio frequency magnetron sputtering method for producing TiO2 shell coatings directly on the surface of ZnO nanorod arrays. ZnO nanorod arrays were firstly fabricated on transparent conducting oxide substrates by a hydrothermal route, and subsequently decorated with TiO2 by a plasma sputtering deposition process. The core/shell nanorods have single-crystal ZnO cores and anatase TiO2 shells. The shells are homogeneously coated onto the whole ZnO nanorods without thickness change. This approach enables us to tailor the thickness of the TiO2 shell for desired photovoltaic applications on a one-nanometer scale. The function of the TiO2 shell as a blocking layer for increasing charge separation and suppression of the surface recombination was tested in dye-sensitized solar cells. The enhanced photocurrent and open-circuit voltage gave rise to increased photovoltaic efficiency and decreased dark current, indicating successful functioning of the TiO2 shell.

Solvent-vapor treatment induced performance enhancement of poly(3-hexylthiophene): methanofullerene bulk-heterojunction photovoltaic cells

The authors report enhanced poly(3-hexylthiophene) (P3HT):methanofullerene (PCBM) bulk-heterojunction photovoltaic cells via 1,2-dichlorobenzene (DCB) vapor treatment and thermal annealing. DCB vapor treatment can induce P3HT self-organizing into ordered structure leading to enhanced absorption and high hole mobility. Further annealing the device at a high temperature, PCBM molecules begin to diffuse into aggregates and together with the ordered P3HT phase form bicontinuous pathways in the entire layer for efficient charge separation and transport. Compared to the control device that is merely annealed, optical absorption, short-circuit current, and power conversion efficiency are increased for the DCB vapor-treated cell.

Surface photovoltage spectra and photoelectrochemical properties of semiconductor-sensitized nanostructured TiO2 electrodes

Three kinds of TiO2 nanostructured thin films and their CdS-sensitized films, consisting of different sizes of TiO2 nanoparticles prepared with different methods, have been investigated. The surface photovoltage spectra (SPS) measurements indicate that the density of surface states on TiO2 is likely dependent upon the details of prepared methods. TiO2 particles prepared from basic sol have more surface states than that prepared from acidic sol. When the TiO2 thin films prepared using the TiO2 sols were sensitized by CdS particles, the SPS responses relative to the surface states on TiO2 from 350 to 800 nm were decreased. The photoelectrochemical properties of nanostructured TiO2 electrodes suggest that the fewer the surface states and the smaller the particle sizes of TiO2, the larger the photocurrent response. For CdS sensitized TiO2 thin film electrode, it is shown that the semiconductor sensitization is an efficient way to decrease the influence of surface states on the charge separation, and can improve the intensity of photocurrent response. (C) 2001 Elsevier Science B.V. All rights reserved.

A study of ion kinetic energy spectrometry of o(-), m(-), and p(-) diol benzene doubly charged ions and singly charged ions in gas phase

With Mass Analyzed Ion Kinetic Energy Spectrometry (MIKES), Collisional Induced Dissociation(CID), and Electron Capture Induced Decomposition(ECID) technigues, the doubly charged ions and singly charged ions from o(-), m(-), and p(-) diol benzene in the EI source have been studied. In terms of the values of the kinetic energy releases(T) of the charge separation reactions of the doubly charged ions and the estimated intercharge distances(R) of the exploding doubly charged ions the transition structures were proposed. Some structural information about the transition states was also obtained. It is of interest that the MIKES/CID spectra of singly charged ions [C6H6O2](+) from the three isomers are of significant differences.

UNIMOLECULAR DISSOCIATION REACTIONS OF DOUBLY-CHARGED IONS [C12H12N2O](2+) AND [C12H12N2S](2+) IN GAS-PHASE

The unimolecular dissociation reactions of doubly charged ions were reported, which resulted from a tandem mass spectrometer and a reversed geometry double focusing mass spectrometer by electron impact, Mass analyzed ion kinetic energy spectrometry (MIKES) was used to obtain the kinetic energy releases in charge separation reactions of doubly charged ions, The intercharge distances between the two charges at transition states can be calculated from the kinetic energy releases, Transition structures of unimolecular dissociation reactions were infered from MIKES and MS/MS.

A Study on the Unimolecular Decomposition of the Doubly Charged Ions Produced from 4 Chloro-toluene Isomers

The unimolecular charge separations and neutral loss decompositions of the doubly charged ions [C7H7Cl](2+), [C7H6Cl](2+) and [C7H5Cl](2+) produced in the ion source by 70 eV electron impact from 3 chloro-toluenes and benzyl chloride isomers were studied

A STUDY OF ION KINETIC-ENERGY SPECTROMETRY OF ORTHO-DICHLORO, META-DICHLORO AND PARA-DICHLORO BENZENE DOUBLY CHARGED IONS [C6H4CL2]2+ AND [C6H3CL]2+ IN GAS-PHASE

The unimolecular Charge separation reactions of the doubly charged ions [C6H4Cl2]2+, [C6H3Cl]2+ produced in the ion source by electron impact from o-, m-, and p-dichloro benzene have been studied using mass analysed ion kinetic energy spectrometry. The values of kinetic energy releases (T) can be calculated from the energy dispersion of product ions. As T essentially reflects the release of coulombic energy, which can be used to calculate the approximate distances R between the two charges immediately before decomposition of the ions. From these data, some structural information about transiton states could be provided. The ECID and CID processes of above doubly charged ions, have also been studied. We found that the CID reactions of (C6H4Cl2)2+ could be used to distinguish three dichloro benzene isomers.

A STUDY OF ION KINETIC ENERGY SPECTROMETRY OF FERROCENE DOUBLY CHARGED IONS IN GAS PHASE

The unimolecular charge separation reactions of the doubly charged ions FeC10H102+, FeC10H theta 2+, FeC10H82+ produced in the ion source by electron impact from ferrocene have been studied using Mass analyzed Ion Kinetic Energy Spectrometry (MIKES) technique. From the values of the kinetic energy releases (T), the intercharge distances (R) of the exploding doubly charged ions in their transition structures have been estimated and some structural informations about the transition states can be obtained. The collision induced reactions of the FeC10H102+ ion with Ar have been studied using MIKES, we postulate a new type of continuing reaction which may be "collisional charge separation induced dissociation".

Effect of implantation of nitrogen into SIMOX buried oxide on its fixed positive charge density

In order to obtain greater radiation hardness for SIMOX (separation by implanted oxygen) materials, nitrogen was implanted into SIMOX BOX (buried oxide). However, it has been found by the C-V technique employed in this work that there is an obvious increase of the fixed positive charge density in the nitrogen-implanted BOX with a 150 out thickness and 4 x 10(15) cm(-2) nitrogen implantation dose, compared with that unimplanted with nitrogen. On the other hand, for the BOX layers with a 375 nm thickness and implanted with 2 x 10(15) and 3 x 10(15) cm(-2) nitrogen doses respectively, the increase of the fixed positive charge density induced by implanted nitrogen has not been observed. The post-implantation annealing conditions are identical for all the nitrogen-implanted samples. The increase in fixed positive charge density in the nitrogen-implanted 150 nm BOX is ascribed to the accumulation of implanted nitrogen near the BOX/Si interface due to the post-implantation annealing process according to SIMS results. In addition, it has also been found that the fixed positive charge density in initial BOX is very small. This means SIMOX BOX has a much lower oxide charge density than thermal SiO2 which contains a lot of oxide charges in most cases.

PHOTOINDUCED CHANGES OF HYDROGEN-BONDING IN SEMIINSULATING IRON-DOPED INDIUM-PHOSPHIDE

After illumination with 1-1.3 eV photons during cooling-down, metastable PH modes are observed by IR absorption at 5 K in semi-insulating InP:Fe. They correlate with the photo-injection of holes, but not with a change of the charge state of the K-related centres present at equilibrium. They are explained by a change of the bonding of H, induced by hole trapping, from IR-inactive centres to PH-containing centres, stable only below 80 K. One metastable centre has well-defined geometrical parameters and the other one could be located in a region near from the interface with (Fe,P) precipitates.

Separation of potential and kinetic electron emission from Si and W induced by multiply charged neon and argon ions

T he total secondary electron emission yields, gamma(T), induced by impact of the fast ions Neq+ (q = 2-8) and Arq+ (q = 3-12) on Si and Neq+ (q = 2-8) on W targets have been measured. It was observed that for a given impact energy, gamma(T) increases with the charge of projectile ion. By plotting gamma(T) as a function of the total potential energy of the respective ion, true kinetic and potential electron yields have been obtained. Potential electron yield was proportional to the total potential energy of the projectile ion. However, decrease in potential electron yield with increasing kinetic energy of Neq+ impact on Si and W was observed. This decrease in potential electron yield with kinetic energy of the ion was more pronounced for the projectile ions having higher charge states. Moreover, kinetic electron yield to energy-loss ratio for various ion-target combinations was calculated and results were in good agreement with semi-empirical model for kinetic electron emission.

Pressurized capillary electrochromatography separation of peptides with strong cation exchange and hydrophilic interaction

A pressurized capillary electrochromatography (pCEC) instrument with solvent gradient capability has been used for the separation of a peptide mixture. Retention mechanism and selectivity of the peptides were studied by pCEC using a strong cation exchange (SCX) column. The effects of applied voltage, supplementary pressure, organic modifier concentration, ionic strength,, and pH value on pCEC separation were investigated. It was found that the retention mechanism of the peptides in this system is based on a mixed mode of hydrophilic interaction, strong cation exchange, and electrophoresis. Compared with the separation results obtained by reverse phase pCEC and capillary electrophoresis (CE), this mixed-mode pCEC is more powerful for the separation of hydrophilic peptides with similar charge-to-mass ratio.

Charge, orbital, and magnetic ordering in YBaFe2O5 from first-principles calculations

First principles calculations using the augmented plane wave plus local orbitals method, as implemented in the WIEN2k code, have been used to investigate the electronic and magnetic properties of YBaFe2O5, especially as regards the charge-orbital ordering. Although the total 3d charge disproportion is rather small, an orbital order parameter defined as the difference between t(2g) orbital occupations of Fe2+ and Fe3+ cations is large (0,73) and gives unambiguous evidence for charge and orbital ordering: Strong hybridization between O 2p and Fe e(g) states results in the nearly complete loss of the separation between the total charges at the Fe2+ and Fe3+ atoms.

Effect of dye concentration on the charge carrier transport in molecularly doped organic light-emitting diodes

The effect of the concentration of 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7, 7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) as dopant in tris(8-quinolinolato) aluminum (Alq(3)) on the charge carrier transport in Alq(3):DCJTB was investigated by measuring the steady current-voltage characteristics and the transient electroluminescence. The dopant concentration dependence of the current-voltage relationship clearly indicates the carrier trapping by the DCJTB molecule. The DCJTB concentration significantly affects the electron mobility in Alq(3):DCJTB. The mobility has a nontrivial dependence on the doping level. For relatively low doping levels, less than 1%, the electron mobility of Alq(3):DCJTB decreases with the doping level. An increasing mobility is then observed if the dopant concentration is further increased, followed by a decrease for doping levels larger than similar to2%. The change of the electron mobility with the DCJTB concentration in Alq(3) is attributed to the additional energetic disorder due to potential fluctuations caused by the dipole-dipole interaction of random distribution dopant at the relatively low doping concentration, and to the phase separation at the high doping concentration.

Numerical Simulation of Particle Separation in An Oil-Sand Separator

The gathering systems of crude oil are greatly endangered by the fine sand and soil in oil. Up to now , how to separate sand from the viscid oil is still a technical problem for oil production home or abroad. Recently , Institute of Mechanics in Chinese Academy of Sciences has developed a new type of oil-sand separator , which has been applied successfully in oil field in situ. In this paper, the numerical method of vortex-stream function is used to predict the liquid-solid separating course and the efficiency for this oil-sand separator. Results show that the viscosity and particle diameter have much influence on the particle motion. The calculating separating efficiency is compared with that of experiment and indicates that this method can be used to model the complex two-phase flow in the separator.