bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser-Excited Fluorescence Detection of Si2 During Silane CVD
Authors: Breiland William G. , Coltrin Michael E. , Ho Pauline 
Published: March 2011

ABSTRACTUsing laser-excited fluorescence, Si2 has been observed in a CVD cell during the deposition of silicon from silane.The formation of Si2 was predicted by our numerical model for CVD which includes a detailed treatment of the chemical kinetics and fluid flow in the gas phase. Our observations of Si2 provide strong support for this model. We also find excellent agreement between the temperature dependence of silicon deposition rates predicted by the model and experimental deposition rates from the literature. These observations indicate that gas-phase chemical reaction kinetics are more important in silane CVD than has been recognized previously.
Uv Absorption Spectra and Photolysis of Some Group II and Group VI Alkyls
Authors: Irvine S. J. C. , Mullin J. B. , Robbins D. J. , Glasper J. L. 
Published: March 2011

ABSTRACTA preliminary study has been made of the UV photolysis of metal-organic compounds of Hg, Cd and Te which could be used for low-temperature, selective-area deposition of cadmium mercury telluride (CMT). High-resolution UV absorption spectra have been measured for dimethylcadmium (CdMe2), dimethylmercury (HgMe2) and diethyltelluride (TeEt2). Possible modes for photodissociation are discussed in the light of these results. The photodissociation of these alkyls was attempted in a hydrogen stream at atmospheric pressure using a mercury-xenon lamp, deposition being being onto a silica reaction tube. Yields of Cd, Hg and Te were measured under different deposition conditions to determine the dependence on UV intensity, alkyl concentration and flow velocity.
Time-Resolved Optical Reflectivity and Transmission During Laser-Induced Oxidation of Cadmium Films
Authors: Baufay L. , Wautelet M. , Pigeolet A. , Andrew R. 
Published: March 2011

ABSTRACTThe laser-induced oxidation of 2000 Å thick cadmium films on glass substrates is studied by measuring the time-resolved reflectivity and transmission of a probe beam. Under CW laser irradiation, the thickness of the oxide layer is shown to increase linearly with time. Also, the velocity, v, of the CdO-Cd interface increases with increasing laser power, with a step when the melting point of Cd is attained. At the highest powers studied in this work, v varies as v = voexp(−a/P), with vo = 6100 Ås−1 and a=4.8 W.
Infrared Laser Photodesorption of Adsorbed Phases
Authors: Hussla Ingo , Chuang T. J. 
Published: March 2011

ABSTRACTAn infrared laser generated from a Nd:YAG laser mixing with a dye laser has been used as a tunable coherent pulsed laser source to photodesorb ammonia from a Cu(100) surface after excitation of the ν3 mode. Timeresolved quadrupole mass spectrometry is sucessfully applied to determine the translational temperatures of the desorbing species from a monolayer coverage on the metal surface. Evidence for desorption induced by vibrational excitation has been obtained and the results are discussed in terms of rapid energy transfer mechanisms.
Excimer Laser-Induced Deposition of InP and Indium-Oxide Films
Authors: Donnelly V. M. , Geva M. , Long J. , Karlicek R. F. 
Published: March 2011

ABSTRACTInP and In-oxide films have been deposited on quartz, GaAs, and InP substrates by excimer laser-induced photodecomposition of (CH3)3InP(CH3)3 and P(CH3)3 vapors at 193 nm. The oxide film refractive index and stoichiometry are close to In2O3. Phosphorus incorporation in the films was greatly enhanced by focusing the laser beam to promote multiple-photon dissociation processes. These conditions also lead to enhanced carbon inclusion in the films, due to formation of species such as CH and CH2 in the gas phase. However, this carbon inclusion could be suppressed by focusing the beam onto the surface at normal incidence. In the irradiated zone InP could be deposited with P(CH3)3-to-(CH3)3InP(CH3)3 ratios of only ∼1:1. The technique offers several potential advantages over conventional metal-organic chemical vapor deposition (MOCVD), including lower temperature, enhanced rates, safer gases, and threedimensional film composition control.Strong atomic In emission is observed in the gas-phase above the depositing film, due to a multiple photon dissociation process. Gasphase fluorescence from P, CH, and C was also observed. These emissions give insight into the photodecomposition mechanism and also serve as a monitor of metal-organic precursor concentrations.
Slipping Transition at a Polymer/Solid Interface
Authors: Migler K. , Hervet H. , Leger L. 
Published: March 2011

AbstractDirect measurements of slippage of a polymer melt within 100 nm of a solid surface, under simple shear, are reported. In the case of a high molecular weight polydimethylsiloxane (PDMS) interacting weakly with the solid surface, a sharp transition between weak and strong slippage is observed as a function of shear stress. For strong polymer-surface interactions, slippage is highly reduced, and no transition is observed. The results are compared to a theoretical model recently proposed by Brochard and de Gennes.
A Dynamic Monte Carlo Simulation of Sorbate Mobility in Zeolites: The Effects of Molecular Crowding on Sorbate Mobility
Authors: Tassel Paul R. Van , Tantra Iwan , Davis H. Ted , Mccormick Alon V. 
Published: March 2011

AbstractA finite lattice of adsorption sites, as shown by Monte Carlo simulation, is used to develop a simple hopping model of small molecules within the alpha cage of zeolite NaA. A two body attractive energetic interaction is employed for occupied pairs of nearest neighbor sites. A many body repulsive interaction term accounts for the crowding associated with site saturation. This term becomes important when the site-site spacing is less than the van der Waals diameter of the adsorbate. The dynamic Monte Carlo method is used to evaluate site to site hopping frequencies as a function of loading based on this potential energy function. As the sorbate-sorbate attractive interaction is increased (or, equivalently, as the temperature is reduced), mobility minima occur at certain lattice occupancies which may be explained by the formation of energetically favorable clusters on the cubocathedral lattice. In other words, molecular crowding can cause sorbate mobility to suffer minima as loading is increased. This prediction is in agreement with recent Xe NMR measurements.
Computer Simulation Study of Adsorption, Isosteric Heat and Phase Transitions of Methane on Graphite
Authors: Jiang Shaoyi , Gubbins Keith E. 
Published: March 2011

AbstractWe report Canonical (NVTMC), Grand Canonical (GOMC) and Gibbs Ensemble Monte Carlo (GEMC) simulations for adsorption of methane on graphite. Lennard-Jones (LJ) potentials are used for the intermolecular interactions, and both structured and structureless (10–4–3) solid-fluid potentials are considered. Several sets of methane-methane L.I parameters have been used in the literature, and we compare results obtained with these sets throughout our simulations. The adsorption isotherm and isosteric heat curve are obtained at 77.5 K and found in good agreement with experiments. The commensurateincommensurate transition (CIT) of methane on a graphite substrate with periodically varying adsorbate-adsorbent potential at 40.0 K is studied and is in qualitative agreement with experiment. The effect of varying the corrugation of the fluid-wall potential on the commensurate and incommensurate phases is explored. The GEMC simulations have been carried out to study the vapor-liquid equilibrium (VLE) of a two-dimensional (2D) LJ fluid with system sizes up to 3000 particles. The effect of system sizes on the critical behavior is investigated. The GEMC method has also been successfully applied to study the VLE in 2D adsorbed films for the first time.
Formation of Mn-As Centers in In1-xMnxAs Diluted Magnetic Semiconductors
Authors: Krol A. , Soo Y. L. , Ming Z. H. , Kao Y. H. , Munekata H. , Chang L. L. 
Published: March 2011

AbstractXAFS spectra at the Mn K-edge were obtained for films of In1-xMnxAs (0.0014 ≤x ≤ 0.12) grown by MBE method at two different substrate temperatures Ts, = 200–210 °C and Ts, = 280–300 ° C. It has been found that Mn-As complexes which consist of a central Mn atom surrounded by six neighboring As most likely arranged in the form of a distorted trigonal antiprism with one or two additional Mn atoms placed on the long axis of the antiprism, can substitute for the In-As tetrahedron in the undistorted zincblende structure. For a composition of x = 0.12 we have found the formation of MnAs clusters with NiAs-like structure in the high-growth-temperature samples. We thus conclude that the magnetic properties of the In1-xMnx As semiconductors are mainly determined by the formation and local structure ol'the Mn-As complexes.
Elementary Rate Laws of Diffusion-Limited Species in the A+T→T Reaction in Low Dimension
Authors: Schoonover Rod , Kopelman Raoul 
Published: March 2011

AbstractThrough computer simulation we look at the elementary reaction rate laws of the trapping reaction A+T→T reaction on a one-dimensional lattice. In particular, we calculate the heterogeneity exponent h of the integrated reaction rate law. However, as the reaction probability p is varied, the heterogeneity exponent becomes a function of time. We find a bifurcation of asymptotic values of h: 1/2 for reactions where p ≤ 1.0 and 0 where p=0. In addition, the usual constraints of the trapping problem have been relaxed, and we look at systems where the A's move and the T remains immobile and the reverse case, where the T moves and the A's sit.
Exact Dynamics in a Model of the Bimolecular Reaction A+B→ 0
Authors: Clément Eric , Leroux-Hugon Patrick , Sander Leonard M. 
Published: March 2011

AbstractWe have previously given an exact solution [1] for the steady state of a model of the bimolecular reaction model A+B→ 0 due to Fichthorn et al. [2]. The dimensionality of the substrate plays a central role, and below d=2 segregation on macroscopic scales becomes important: above d=2 saturation sets in for finite size systems. Here we extend our treatment to give an exact account of the dynamics and show how various initial conditions develop into the segregated and saturated regimes. In certain conditions we find logarithmic relaxation which is related to the dimensionality.
Colloidal Aggregation in a Binary Mixture Near its Demixing Temperature
Authors: Broide Michael L. , Beysens Daniel 
Published: March 2011

AbstractWe have investigated temperature-induced aggregation of silica colloids in a binary mixture of 2,6-lutidine and water. Aggregation occurs in the one-phase region of the binary mixture and can be reversed by cooling the sample.Using low-angle light scattering, we have determined the growth kinetics and aggregate structure for this system. We find that the time dependent scattered intensity is well described by I(q, t) = ¯(t)/[1 + (q¯R(t))2/10]2\, where the weight-average cluster mass ¯I(t) ⋧ t, and the average cluster radius ¯(t) -çt1/3.Our results indicate that this experimental system generates compact clusters, ¯ ⋧ ¯ 3, and that the rate of aggregation is diffusion limited. The dense, non-fractal, structure we observe suggests that the bonds between the silica spheres are not rigid, and supports the hypothesis that aggregation is induced by the adsorption of lutidine on the silica surface.
Biotinylated Polythiophene Copolymer – a Novel Electroactive Biomaterial Utilizing the Biotin-Streptavidin Interaction
Authors: Lim Jeong-Ok , Kamath Manjunath , Marx Kenneth A. , Tripathy Sukant K. , Kaplan David L. , Samuelson Lynne A. 
Published: March 2011

AbstractA novel hierarchical biomaterial capable of incorporating any biotinylated biomolecule has been created. Our strategy is to biotinylate one-dimensional electroactive polymers and use a bridging streptavidin protein on Langmuir-Blodgett (LB) organized films. The following copolymeric system which enables functionalization of other molecules and formation of good monolayers was employed. Biotinylated poly(3-methanolthiophene-co-3-undecylthiophene) (B-PMUT) demonstrated a significantly better isotherm implying superior molecular packing compared to poly(3-methanolthiophene-co-3-undecylthiophene) (PMUT) on the LB airwater surface. The isotherm showed significant area expansion when streptavidin was injected below the B-PMUT monolayer in 0.1mM NaH2PO4/0.1 M NaCl buffer (pH 6.8) subphase. We then incorporated biotinylated phycoerythrin (B-PE) into this novel biomaterial by binding the unoccupied biotin binding sites on the bound streptavidin (4 sites total). The pressure-area isotherm of the protein injected monolayer showed area expansion. A characteristic fluorescent emission peak at 576nm was detected from the monolayer transferred onto a solid substrate. These observations demonstrated the function of B-PMUT in hierarchical monolayer assembly of molecules incorporating the biotin / streptavidin interaction.
Specific Interaction of Influenza Virus with Organized Assemblies of Polydiacetylenes
Authors: Charych Deborah H. , Spevak Wayne , Nagy Jon O. , Bednarski Mark D. 
Published: March 2011

AbstractSupramolecular organizates of liposomes and Langmuir-Blodgett (LB) films are described which are capable of specifically binding to pathogens such as influenza virus. The specific interaction is between the hemagglutinin protein of the virus and an α-C-glycoside of sialic acid expressed on the surface of the liposome or LB film. Sialic acidcontaining liposomes were found to inhibit influenza virus infectivity in cell culture, and may provide a basis for new materials which act as therapeutic agents. Sialic acid-containing LB films also specifically bind to the influenza virus. In this case, the conjugated polymer backbone acts as a built-in reporter of the binding event, measurable by a chromatic change in the visible absorption spectrum. These films may provide a basis for new materials which act as direct detectors of binding
Decalcification Studies on Avian Eggshell
Authors: Agarwal M. , Xiao S.Q. , Heuer A.H. 
Published: March 2011

AbstractAvian eggshells are one of the most rapidly calcifying systems known. Although the entire shell contains ∼ 97 weight % CaCO3, etching in EDTA reveals great spatial variability in etching rate. A correlation between the etching rate of various regions and the relative positions of the different parts in the calcium reserve assembly (CRA) has been made; the CRA is the source of calcium during natural decalcification by chick embryos.
Spider Silk Proteins
Authors: Hinman Mike , dong Zhengyu , Xu Ming , Lewis Randolph V. 
Published: March 2011

AbstractDragline silk has been shown to consist of two proteins, Spidroins 1 and 2, which form this unique fiber. The cDNAs for these two proteins have been sequenced and a structure proposed which accounts for both the tensile strength and elasticity of dragline silk.
High Ionic Conductivity of Polymer Complexes Formed by Polypyridinium, Pyridinium, and Aluminium Chloride
Authors: Rikukawa Masahiro , Yamada Shinichiro , Sanui Kohei , Ogata Naoya , Watanabe Masayoshi 
Published: March 2011

AbstractNew ion conductive polymer complexes were formed by dissolving poly(1-butyl-4- vinylpyridinium) salts into room temperature molten salts consisting of 1-butylpyridinium salts and aluminium chloride. The viscoelastic films were fabricated from the molten salts added at least 10 mol % of the polypyridinium salts. The ionic conductivities of the polymer complexes were in the range of 10−3−10−4 Scm−1 at room temperature and were affected by their composition.
Oxidation States in Layered Nickel Oxide Based Electrode Materials
Authors: Delmas Claude 
Published: March 2011

AbstractNiO2 slabs made of edge-sharing NiO6 octahedra are the main structural parts of the positive electrode materials involved in Ni-Cd, Ni-M- and Li-LiNiO2 secondary batteries. These electrochemical systems are among the best ones for applications. The behavior of all these electrode materials can be optimized by substituting several cations for nickel.The effect of iron and cobalt substitution has been investigated in detail. The oxidation state modifications resulting from the electrochemical cycling have been characterized from magnetic, conductivity, thermoelectric-power and Mössbauer studies. The overall results show that nickel ions are oxidized to the tetravalent state before cobalt ions. More surprisingly, the oxidation of iron-nickel mixed phases shows the simultaneous presence of tetravalent iron and nickel ions in the low spin configuration. For the first time, in situ M6ssbauer measurements have been performed during the cycling of a nickel-cadmium cell.This cationic distribution results from the competition between the intrinsic redox properties of the 3d cations and the accommodation of the oxidation levels to the ligand field imposed by the prevailing cation.
Polymer-Based Electrochemical Devices
Authors: Arbizzani C. , Mastragostino M. , Meneghello L. , Andrieu X. , Vicedo T. 
Published: March 2011

AbstractSelected findings of ongoing investigations of variable light-transmission electrochromic devices using electronically conducting polymers as electrochromic materials are presented and discussed.An obvious requisite for electrochromic windows is an all-solid configuration with polymer electrolyte; in this connection testing data of a new hybrid electrolyte based on a polymer network including a plasticizer are reported and discussed.
Structural and Physical Characterization of Li2O:P2O5:MO3 (M = Cr2, Mo, W) Ion Conducting Glasses
Authors: Chowdari B.V.R. , Tan K.L. , Chia W.T. 
Published: March 2011

AbstractThe conductivity of the Li2O:P2O5:MO3 (M = Cr2, Mo, W) glasses increases as P2O5 is progressively substituted by MO3 and as the Li2O content increases. Amongst the glass compositions studied, the 0.50Li2O:0.20P2O5:0.30WO3 glass has the highest conductivity at 25°C of 2. 1×10−6 ×−1 cm−1. The glass transition temperature of the glasses increases initially with network former substitution, reaches a maximum at around MO3/P2O5 = 1, and decreases with further substitution. X-ray photoelectron spectroscopy reveals the presence of M ions in more than one oxidation state and oxygen species such as P=O, P-O-P, P-O, M-O-M, M-O and P-O-M. Raman spectroscopy shows that the Li2O:P2O5:MoO3 and Li2O:P2O5:WO3 glasses consist of PO4, MoO4 (WO4) and MoO6 (WO6) polyhedra while the Li2O:P2O5:Cr2O3 glasses consist of the PO4 and CrO6 polyhedra only. The phosphate groups are preferentially modified by Li2O in comparison with the tungstate, molybdate and chromate groups. The increasing number of non-bridging oxygen atoms per phosphate group may be related to the increasing conductivity with the progressive substitution of MO3 for P2O5.
Protonic Conduction in Y-, Yb- and Sc-Doped SrZrO3 Ceramics
Authors: Liang K.C. , Lee I.Y. , Nowick A.S. 
Published: March 2011

AbstractProtonic conduction of SrZrO3 doped with Y3+(5%), yb3+(5 and 10%) and Sc3+(5, 10, 15 and 20%) has been investigated in a frozen-in condition at 20-400°C following a high-temperature pre-treatment in water vapor. Water uptake was also determined gravimetrically. The pure sample shows no proton incorporation and relatively low conductivity. The oxygen partial pressure dependence of conductivity under dry atmosphere shows hole conduction only when P(O2) >10−5 atm. All of the doped samples show good protonic conduction and a non-classical H2O/D2O isotope effect. The conductivity and water uptake is always higher for samples slowly cooled from the pre-treatment than for quenched samples. The activation energy, as well as the pre-exponentials, of the slowly cooled samples consistently suggest Stage II behavior, with an activation energy for proton migration of 0.61±0.02eV and an effective proton concentration close to the actual concentration. It is concluded that SrZrO3 deserves serious consideration as a proton electrolyte.
Factors Affecting Ion Transport in Fast-Ion Conductivity Solids
Authors: Secco E. A. 
Published: March 2011

AbstractFast-ion conduction in solids is considered a paradigm for structure-property relation where ionic conductivity σ = nqµ, n the concentration of charge carrier q, and µ. the mobility of the carrier. The critical conductivity determining factor, ceteris paribus, is the carrier mobility which depends on the geometry of anion array and structure in the solid. Factors inherent in the structural framework include “free” volume, “bottleneck” size, lattice disorder, etc. Other non-structural factors that can play a vital role, even a dominant role, in enhancing ionic conductivity are charge carrier concentration, ion-ion interactions or bonding characteristics, vibrational amplitudes of neighboring ions, lattice compressibility or resiliency, rotational motion of anions, ion size, etc. Many aspects of these factors will be examined in the light of recent studies and the results on some isostructural and isomorphous sulfates and other related structures to evaluate their relative contributions.
Optical Spectroscopies of Lithium-Intercalated Compounds
Authors: Julien C. 
Published: March 2011

AbstractLayered compounds are known to form lithium intercalation complexes as electron donor systems. A charge transfer which can strongly affect the electronic properties of the host lattice, and a change of preferential crystallographic parameters without destruction of the original structure are the main effects occuring during intercalation. Optical spectroscopies such as Raman scattering, far-infrared reflectivity, absorption measurements and photoluminescence have been carried out for the study of electronic and structural modifications. Upon lithium intercalation, lattice dynamics and electronic band structure change in numerous layered compounds. The optical properties of transition-metal dichalcogenides, non-transition metal chalcogenides and transition-metal oxides are presented and discussed with the aim of a better understanding of the intercalation process and establish some guide lines for improving the performances of these materials in their most important applications.
Synthesis and Characterization of Microcrystalline TiS2 for Use in Cathodes
Authors: Donahue Edward J. , Dominey Lawrence A. , Koch Victor R. , Blakley Thomas J. , Goldman Jay L. 
Published: March 2011

AbstractTitanium disulfide is a particularly promising cathode material for very high cycle life applications in secondary lithium batteries due to the reversible nature of the intercalation of lithium into the host TiS2 lattice. It has long been known that the mechanical stress of the intercalation process is minimized if TiS2 crystal size is kept below 10μm. It has also been suspected that minimizing crystal thickness would improve the kinetics of at the onset of lithiation by minimizing the forces which would have to be overcome in expanding the host lattice. We have synthesized three different types of microcrystalline TiS2, two thin film and one powder, and have compared their performances to that of a large crystalline powder. Lithium ion diffusivity and pulse power performance of the four materials were compared. It was found that the two thin film materials exhibited extraordinary pulse power rate capabilities while the two powder materials were limited in their performance by the constraints of the composite cathode matrix.