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991.
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Filippus S. Roux 《Optics Communications》2010,283(24):4855-4858
Stochastic (i.e. random and quasi-random) optical fields may contain distributions of optical vortices that are represented by non-uniform topological charge densities. Numerical simulations are used to investigate the evolution under free-space propagation of topological charge densities that are inhomogeneous along one dimension. It is shown that this evolution is described by a diffusion process that has a diffusion parameter which depends on the propagation distance. 相似文献
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995.
The fabrication of photo‐degradable, protein–polyelectrolyte complex (PPC)‐coated, mesoporous silica nanoparticles (MSNs) and their controlled co‐release of protein and model drugs is reported. Random copolymers composed of oligo(ethylene glycol) monomethyl ether methacrylate (OEGMA), and a photolabile o‐nitrobenzyl‐containing monomer, 5‐(2′‐(dimethylamino)ethoxy)‐2‐nitrobenzyl methacrylate (DENBMA), are first anchored onto the MSNs and then quaternary aminated, to obtain positively charged P(OEGMA‐co‐TENBMA) which exhibits photo‐induced charge conversion characteristics. PPCs consisting of P(OEGMA‐co‐TENBMA) and the protein bovine serum albumin (BSA) are utilized as capping agents for the nanopores of the MSNs. Upon UV irradiation, charge conversion of P(OEGMA‐co‐TENBMA) can lead to the disruption of PPCs on MSNs and co‐release of BSA and rhodamine B by electrostatic repulsion. 相似文献
996.
Luiz F. Lepre Fabiana Inoue Paola Corio Paulo S. Santos Rmulo A. Ando 《Journal of Raman spectroscopy : JRS》2013,44(4):567-572
The spectroscopic characterization of cadion or 1‐(4‐nitrophenyl)‐3‐(4‐phenylazophenyl)triazene, its anionic species and its complexes with Hg2+, Cd2+ and Ni2+ in DMSO solution is presented. Resonance Raman (RR) and UV–vis spectroscopy were the techniques of choice with results supported by density functional theory calculations. As previously reported, the UV–vis data indicate distinct absorption spectra for the five species mentioned, allowing for spectrophotometric metal differentiation. In order to understand the electronic spectra of such species, we performed a detailed RR investigation, where the spectral profiles revealed the vibrational modes mainly involved in the chromophoric moieties. The distinct enhancement profile observed for each species suggests that the charge transfer from the π‐system to the electron withdrawing NO2 group is modulated by the electron donating triazene moiety, depending on the metal attached. The results reported herein show that RR spectroscopy can be potentially used in the metal detection of multicomponent samples by the proper choice of the excitation wavelength. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
997.
We demonstrate, analytically and experimentally, a simple, but effective method to determine the topological charge of an optical vortex by using a spherical bi-convex lens, a ubiquitous optical element found in any optics laboratory. Just by tilting the lens and recording the intensity distribution of a propagating vortex at a predicted position past the lens, we have been able to measure both the sign and the magnitude of the topological charge m up to m=±14. Our experimental results are in excellent agreement with analytical predictions. 相似文献
998.
R. Bharathikannan A. Chandramohan M. A. Kandhaswamy J. Chandrasekaran R. Renganathan V. Kandavelu 《Crystal Research and Technology》2008,43(6):683-688
The organic NLO material 2‐nitro aniline and picric acid (2NAP) was synthesized, needle shaped single crystals of dimension 10 × 1 × 0.8 mm‐3 were grown by slow evaporation solution growth technique from the saturated solution of the title compound in chloroform at ambient temperature. The material was characterized through elemental analysis, powder XRD, 1H NMR, 13C NMR and FTIR techniques. The various planes of reflection have been identified from the XRD powder pattern. The formation of the charge transfer complex was confirmed by UV‐VIS spectroscopy. The thermal stability of the crystals was investigated using TG/DTA analyses techniques. The second harmonic generation (SHG) efficiency of the material was estimated using Nd: YAG laser as source. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
999.
Anodic stripping voltammetry was made in AgNO3 solution, here Ag was deposited under long term potentiostatic conditions to evaluate the reduction charge, qr, and then was stripped by linear sweep voltammetry to determine the oxidation charge, qo. The charges were unbalanced, satisfying ca. qo=0.7|qr|, where other possible reduction charge such as by dioxygen and dichlorosilver were subtracted. The 30 % loss of the anodic charge can be ascribed to the negative capacitance by the potential sweep generation of Ag+. The generated Ag+ forms a dipole with a counter ion, of which orientation is the same as the direction of the externally applied electric field and opposite to the dipoles of solvent. The redox dipole decreases the conventional double layer capacitance caused by solvent dipoles, and high concentrations of Ag+ takes the capacitance to be negative values. The unbalanced charge, however, has no influence on quantitative determination of concentrations Ag+ by use of a calibration line. 相似文献
1000.
Dr. So-Yeon Park Sehoon Han Dr. Younghoon Kim Prof. Sohee Jung Prof. Dong Hoe Kim Dr. Gill Sang Han Prof. Hyun Suk Jung 《Chemphyschem》2019,20(20):2657-2661
Multiple exciton generation (MEG) has great potential to improve the Shockley-Queisser (S-Q) efficiency limitation for colloidal quantum dot (CQD) solar cells. However, MEG has rarely been observed in CQD solar cells because of the loss of carriers through the transport mechanism between adjacent QDs. Herein, we demonstrate that excess charge carriers produced via MEG can be efficiently extracted using monolayer PbS QDs. The monolayer PbS QDs solar cells exhibit α=1 in the light intensity dependence of the short-circuit current density Jsc (Jsc∝Iα) and an internal quantum efficiency (IQE) value of 100 % at 2.95 eV because of their very short charge extraction path. In addition, the measured MEG threshold is 2.23 times the bandgap energy (Eg), which is the lowest value in PbS QD solar cells. We believe that this approach can provide a simple method to find suitable CQD materials and design interface engineering for MEG. 相似文献