bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tetrazine-Bridged Phthalocyaninato Metal Complexes: A New Class Of Intrinsic Semiconductors
Authors: Hanack Michael , Barcina Jose Osio , Pohmer JöRg , Witke Elisabeth 
Published: March 2011

ABSTRACTStacked transition Metal Macrocycles [Macm (L)]n with M e.g. Fe, Ru, Os, Co, Rh and Mac = phthalocyanine (Pc) 1,2- or 2,3-naphthalocyanine (1,2-, 2,3-Nc) have been synthesized by us. The bridging ligands (L) are e.g. pyrazine (pyz) or s-tetrazine (tz). In general, these complexes [Macm (L)]n are insoluble in organic solvents, however, soluble oligomers [R4Pcm (L)]n can be prepared using Metallomacrocycles RnPcm, R = t-bu, et, OR, M = Fe, Ru, which are substituted in the périphérie positions.A systematic investigation of the influence of the bridging ligánds on the semiconducting properties in [Macm (L)]n reveal, that changing L, e.g from dabco over pyz to tz leads to a steady increase of the semiconducting properties without external oxidative doping. Powder conductivities in the order of 0.1 S/cm can be reached by using s-tetrazine, 3,6-dimethyl-j-tetrazine (Me2tz) and others, e.g. fu marodini tri le as the bridging ligands. The intrinsic conductivities are a result of the low oxidation potential of tz and Me2tz and due to the low lying LUMO in the corresponding bridged systems [Macm (tz)]n.The electrical and physical properties, especially the UV and the Möβbauer spectra for the tetrazine-bridged Macrocyclic Metal complexes are discussed in respect to intrinsic semiconducting properties of these compounds.
High Electrical Conductivity in Organic Single-Component Systems Based on 2,5-Dimethylthio-TCNQ
Authors: Zambounis J. S. , Mizuguchi J. , Hediger H. , Pfeiffer J. , Schmidhalter B. , Rihs G. , Chauvet O. , Zuppiroli L. 
Published: March 2011

ABSTRACT2,5-dimethylthio-TCNQ has been newly synthesized, and its optical and electrical properties have been investigated in evaporated films. A high electrical conductivity of σ=2× 10−5 Scm−l has been measured at room temperature. The present single-component system is found to contain 2×1017 spins/cm3. The charge carriers are presumably due to incorporated impurities which give the ESR signals. Carrier hopping is considerably facilitated by close intermolecular S-N contacts between the S atom of the -SCH3 group of one molecule and the N atom of -C≡N group of the neighboring Molecule.
Infrared And Raman Spectroscopy Of Organic Electron Conductors
Authors: Ridaura R. , GóMez R. , Marquina V. , Aburto S. , Marquina M. L. , Jiménez M. , Robles-Martínez J. G. , Salmerón-Valverde A. 
Published: March 2011

ABSTRACTFT-Raman and infrared (IR) spectra of a series of TTF-fluorene derivative family were obtained using a conventional IR spectrometer and a FT-Raman spectrometer. The Raman shifts of the observed band (ν3 stretching band) changes from sample to sample and we correlate these changes with the degree of charge transfer between the donor (TTF) and the acceptor (fluorene derivative) Molecules. These results are compared with those obtained from changes in the IR absorption frequencies of the C≡N stretching mode in the acceptor Molecule.
Poly (L,4-Naphthylene Sulfide) Oligomers: Electronic And Vibrational Spectra Of The Pristine And Oxidized Forms
Authors: Piaggio P. , Petrillo G. , Novi M. , Dell'Erba C. 
Published: March 2011

ABSTRACTNew naphthalene-sulfur compounds, oligomers of poly (l,4-naphthylene sulfide), have been synthesized and studied by electronic and vibrational spectroscopy in both pristine and oxidized forms. It has been found that the charged defects induced on these molecules are Much More stable than in the corresponding 1,4-phenylene derivatives. Nevertheless their physical properties are strongly affected by steric effects which hinder a regular arrangement of the repeating units.
Investigation Of Luminescence And Absorption Spectra Of Bedt-Ttf And Its Ion Radical Salt
Authors: Kozlov M. E. , Tanaka Y , Tokumotot M. , Tani T. 
Published: March 2011

ABSTRACTLuminescence with maximum near 1.96 eV of organic donor compound bis (ethylenedi-thio) tetrathiafulvalene (BEDT-TTF) was observed in crystals and frozen at low temperature solution. It was found that solid state effects sharply reveal themselves in excitation spectra of the substance and have almost no influence on the shape of the emission. Intensity of the emission is strong at liquid He temperature but rapidly decreases with heating of the sample as well as after modification of charged state of molecules forming the crystal and is very weak in case of Monovalent (BEDT-TTF) Br salt. Shape of the luminescence spectra correlates with the absorption of the investigated compounds. The data obtained can be interpreted assuming dimer-like arrangement of molecules in the crystal structure.
Molecularly Engineered Polymer Leds
Authors: Moratti Stephen C. , Bradley Donald C. , Friend Richard H. , Greenham Neil C. , Holmes Andrew B. 
Published: March 2011

ABSTRACTPolymeric light emitting devices may be fabricated from a simple structure consisting of a low work function cathode (typically calcium or Magnesium), a conjugated semiconducting polymer and a transparent anode (typically indium-tin oxide). Optimum device efficiencies require the balanced injection of electrons and holes. This paper describes the application of molecular engineering in the design of a family of poly (cyanoterephthalylidenene) s which show increased electron affinity over the unsubstituted analogue [poly (p-phenylenevinylene) PPV]. In particular these polymers as the emissive layer in a bilayer device with indium tin oxide (ITO, positive transparent contact) and aluminum (stable negative contact) and PPV as a hole transporting layer exhibit internal efficiencies up to 4%.
High Glass Transition TemperatÜRe Electro-Optic Polymers
Authors: Wu Chengjiu , Beeson Karl , Ferm Paul , Knapp Charles , Mcfarland Michael J. , Nahata Ajay , Shan Jianhui , Yardley James T. 
Published: March 2011

ABSTRACTDisperse Red-1 type chromophores were attached to the backbones of PMMA, polyvinyl-phenol as well as the styrene-Maleimide alternative copolymer and glass transition temperatures of these three polymer derivatives were in the range of 125, 165, and 245°C, respectively. We have also, for the first time, attached EO chromophores to some thermostable cardo-polymers. Fluorene derivatives in which the 2- and 7-positions were substituted with an electron accepting and an electron donating substitutem, respectively, were made polymerizable through their reactive functional groups at the 9,9′-positions. Various condensation polymers were prepared. These polymers are amorphous, film-forming, thermostable, and having Tg ranging from 150 to 300°C. These polymers exhibit strong electro-optic properties after electrode poling. Thermal stabilities of these polymers were compared by following the spectral decay of the chromophore and the decay of the electro-optic coefficient. The loss of EO activity at elevated temperature can be realized as a combination of chromophore reorientation and chemical degradation.
Channel Waveguides and Modulators Fabricated From High Temperature Second Order Nonlinear Optical Polymers
Authors: Kenney J. T. , Binkley E. S. , Jen A. K-Y. , Wong K. 
Published: March 2011

ABSTRACTBuried channel wave guides have been fabricated from thermally stable non linear optical polyimides. The Material system consists of a polyimide cladding and a polyimide based active Material. The buried channel wave guides are fabricated by a trench and fill process. This process was used for the fabrication of active wave guides at process temperatures above 300 °C. Single Mode wave guides, and Mach-Zenhder interferometers, were fabricated with attenuation < 2 dB/cm. Active Mach-Zehnder interferometers with a Vπ phase shift of 50 volts and the low attenuation were fabricated. Thermal aging of the poled active device demonstrated no change in activity after 30 Minutes at 230°C.
A Synthetic Approach for the Incorporation of Highly Efficient, Thermally Stable Second Order Nonlinear Optical Chromophores Into Side-Chain Polymers
Authors: Drost Kevin J. , Jen Alex K-Y. , Pushkara Rao V. , Mininni R. M. 
Published: March 2011

ABSTRACTA new synthetic method is developed to incorporate efficient nonlinear optical chromophores containing thiophene conjugating units and tricyanovinyl acceptors into side-chain polymers. This approach emphasizes the incorporation of the tricyanovinyl groups into the pendant side chains after the desired polymer is formed.
Hyper-Rayleigh Scattering (Hrs) In Isotropic Media
Authors: Hendrickx Eric , Verbiest Thierry , Clays Koen , Samyn Celest , Persoons Andre 
Published: March 2011

ABSTRACTIn this paper some of the more important Hyper Rayleigh Scattering (HRS) Measurements performed in our laboratory are reviewed. The results of experiments conducted on polymers, the protein Bacteriorhodopsin, retinal derivatives and octopoles are presented. Basic HRS theory, along with a brief description of the HRS set-up, is also included.We demonstrate that the experimental simplicity of HRS allows for an accurate determination of the first hyperpolarizability of molecules that could not have been measured by the more traditional Electric Field Induced Second Harmonic Generation (EFISHG) technique.
Optical Properties and Photoexcitations in Regularly Alternating Conjugated Copolymers
Authors: Tubino R. , Botta C. , Destri S. , Porzio W. , Rossi L. 
Published: March 2011

ABSTRACTWe report in this short paper a preliminary account on the design, preparation, optical characterization and photoexcitation of a class of novel conjugated polymers consisting of regularly alternating thiophene and benzene sequences, which Might represent Models for one-dimensional superlattices. Optical absorption and emission spectra suggest that the barriers produced by the phenylene Moieties do not interrupt the conjugation but can produce localization effects. Resonant Raman spectra indicate that a selective response of the thiophene Moiety occurs upon excitation with visible light. Moreover these Measurements confirm the presence of a confinement on the thiophene blocks, while the biphenil Moiety does not appear to feel the energy barrier and behaves as the corresponding polymer poly (paraphenylene) (PPP). CW photomodulation spectra show that the formation of long-lived bipolarons takes place only if the thienylenic Moiety is long enough to accomodate the lattice distortion.
Broad Temperature Range Of Chiral Smectic C Phase In Some Ferroelectric Side-Chain Liquid Crystalline Polysiloxanes Containing Oligooxyethylene Spacers
Authors: Hsiue G. H. , Chen J. H. , Hsu C. S. 
Published: March 2011

ABSTRACTThe Mesomorphic behaviors of some ferroelectric liquid crystalline monomers and side-chain polysiloxanes studied by X-ray diffraction Measurement, differential scanning calorimeter and polarizing Microscope. All obtained polymers exhibit wide temperature range of chiral smectic C phase including room temperature.These Mesogenic structures contain oligooxyethylene spacers and (S)-2-Methyl-l -butyl chiral tail via a three phenyl ester linkage (i.e. -Ph-COO-Ph-Ph- or -Ph-Ph-COO-Ph-). Two series of monomers with different biphenyl group linkage position were compared. One shows a novel twisted smectic A phase, in addition to the liquid crystalline sequence (Ch→SA→Sc*) obtained between cholesteric phase and smectic A phase. It also presents an unusual smectic A and chiral smectic C phase.All the prepared polymers present smectic Mesomorphism. As the unit of flexible oligooxyethylene spacers increases, the clearing temperature decreases and the stability of the smectic phase also increases.
Domains In Nematic Elastomers
Authors: Ten Bosch A. , Varichon L. 
Published: March 2011

ABSTRACTA theory based on an elastic model and including coupling between elastic deformation and nematic order parameter as well as an interaction between crosslinks and orientation is given. The nematic order parameter and the stress tensor have been determined on elongation and as a function of temperature as well as he anisotropy of the conformation of a side chain liquid crystal elastomer on application of a mechanical stress. A transition from a turbid, low ordered polydomain phase to a transparent, Monodomain is shown to occur.
Long-Lived Defects In Polycarbazolyld1 Acetylenes. Photoinduced Vis And Infrared Spectra
Authors: Dellepiane G. , Cuniberti C. , Comoretto D. , Musso G. F. , Piaggio P. , Speroni F. , Botta C. , Luzzati S. 
Published: March 2011

ABSTRACTPhotoinduced absorption spectra of different polycarbazolyldiacetylenes in the visible and infrared regions are reported. Long-lived bipolaronic defects, photogenerated by excitation above the band-gap (2.54 eV), are found responsible for the observed signals. Associated with these defects, photogenerated infrared active vibrations (IRAV) are observed as absorption bands or apparent bleachings arising from Fano-type interference. This different behaviour originates from the different degree of overlap of the IRAV Modes with the associated low-energy bipolaronic absorption.
Fabrication Of Organic Dye-Coated High-Tc Superconductor Optical Devices: Interface Chemistry And Properties
Authors: Jurbergs David , Zhao Jianai , Haupt Steven G. , Mcdevitt John T. 
Published: March 2011

ABSTRACTThe preparation and characterization of a new generation of optical sensors fabricated from high-temperature superconductor (HTSC) thin films is reported herein. These new hybrid devices are prepared using HTSC thin films which are coated with organic dye overlayers. These systems have been shown to respond selectively to those wavelengths which are absorbed strongly by the molecular dye. Methods for fabricating the superconductor element and depositing the dye layer are discussed. Moreover, scanning electron microscopy and resistivity versus temperature measurements are utilized to characterize these hybrid structures.
Conductive Polymer Switch For Controlling Superconductivity
Authors: Haupt Steven G. , Lo Rung-Kuang , Riley David R. , Zhao Jianai , McDevitt John T. 
Published: March 2011

ABSTRACTElectrochemical techniques are exploited to fabricate conductive polymer/high-Tcsuperconductor sandwich structures. In such hybrid polymer/superconductor systems, it is found that when the polymer is oxidized to its conductive state, the transition temperature (Tc) and critical current (Jc) of the underlying superconductor film are suppressed. Reversible Modulations in the values of the transition temperatures up to 50 K are noted for these structures. Upon reduction of the conductive polymer layer back to its non-conductive form, Tc is found to return to values close to those acquired for the underivatized YBa2Cu3O7-δ film. Thus, the principle of a Molecular/superconductor switch for controlling superconductivity is demonstrated.
Poly (SNS) Quantitative Electrosynthesis and Electrodissolution
Authors: Otero T. F. , Brillas E. , Carrasco J. , Figueras A. 
Published: March 2011

ABSTRACTThe electrogeneration and electrodissolution of poly (SNS) have been improved by using aqueous acetonitrile solutions having a 1% (ν/ν) of water constant. Compact, adherent and thick films (until 0.4 Mg cm-2) were galvanostatically electrogenerated. The electrodeposited (oxidized) polymer is insoluble in 0.1 M L?CIO4 aqueous acetonitrile solution and solubilizes by cathodic reduction. Both, electrogeneration and electrodissolution, are faradaic processes. Those facts mimic electrodeposition and electroerosion of metals and their concomitant industrial applications. New technological possibilities using polymers in electrophotography, electroreprography, electropolishing, electro-erosion and electromachining are open through polymeric electrodissolution altogether to a new processible way, through the obtained solution, for the conducting polymers.
Synthesis and Crystal Structure of C60 Complex with a Symmetrical Donor of 2,3,6,7,10,11- Hexamethoxytriphenylene (HMT)
Authors: Chiang Long Y. , Swirczewski John W. , Liang Keng S. 
Published: March 2011

ABSTRACTWe have successfully synthesized single crystals of C60 fullerene complex with a symmetrical triplet donor of 2,3,6,7,10,11-hexamethoxytriphenylene (HMT). All spectroscopie data and analyses support the chemical composition of this complex as C60(HMT)2. Single crystals of C60(HMT)2 are, at 20±1 °C, cubic, space group Fd3c-Oh8 (No. 228) with a = 30.251(9) Å, α = 90.00°, V = 27682(30) Å3, Z = 16 (dcalcd = 1.476 gcm-3), and Ru (unweighted) = 0.098.
Vertical, Dual Gate CMOS Structure in Two Laser-Recrystallized Silicon Layers over Oxidized Silicon Substrate
Authors: Kenyon P. , Dressel H. , Negri A. 
Published: March 2011

ABSTRACTA seven mask CMOS process that provides vertically integrated structures with joint gates is described. The structures have been characterized as individual NMOS and PMOS transistors. An implant technique will be described which may permit the fabrication of fully self-aligned CMOS structures.
Modeling of Polysilicon Resistors, P-N Junction Diodes and Mosfet's
Authors: Khondker A. N. , Ahmed S. S. , Liou T. , Kim D. M. 
Published: March 2011

ABSTRACTConductivity in bulk polysilicon is discussed, applicable over a wide range of dopant concentration, temperature, grain size and trap density. The I-V behavior in a lateral poly p-n junction is analytically modeled, incorporating the effects of carrier lifetime operative in crystalline grain and amorphous conducting boundary. In particular, the extremely short carrier lifetime within the grain boundary is shown to provide an ohmic conduction channel in a direction parallel to current flow. This ohmic current can account for the unusually high current levels observed at small applied voltages. Also, the shift of the threshold voltage of MOS devices, as influenced by grain traps near the channel region, is analysed.
Liqiuid Crystal Display Fabricated from Laser Recrystallized Silicon on Bulk Fused Silica
Authors: Hawkins W. G. , Drake D. J. , Goodman N. B. , Hartman P. J. 
Published: March 2011

ABSTRACTThis paper discusses four aspects of fabrication of an active address liquid crystal array from laser recrystallized polycrystalline silicon: recrystallization, processing, device performance and array fabrication. The recrystallization process produces material which is imperfect by silicon wafer standards, but which contains few incoherent defects. The material was used to fabricate discrete n-channel MOS devices which had consistent off currents of 10−11 amps (0.4pA/μm of channel width) and on currents of 10−4 amps. Device threshold is controlled to + 200 mV and channel mobility is 500 to 600 cm2 /V-sec. The crossovers between Al/1% Si source and degenerately doped polycrystalline silicon gate lines were fabricated by use of high temperature reflowed, phosphorus doped chemical vapor deposited SiO2. Completed arrays had very few defects (no crossover defects and 0.3% bad devices).
Semitransparent Silicide Electrode Formed on the Surface of a-Si:H
Authors: Tsukada T. , Seki K. , Yamamoto H. , Sasano A. 
Published: March 2011

ABSTRACTThin silicide layers are found to be formed through solid state reaction between hydrogenated amorphous silicon(a-Si:H) and metals. The method of formation of the silicide layer is very simple: deposition of metal on top of amorphous silicon layer and annealing and etching of the residual metal layer. The reaction kinetics and properties of this layer are described. The thickness of this silicide layer is estimated to be 5 nm. Accordingly, it can be used as a transparent electrode in a-Si:H photodiodes. Photodiodes using this semitransparent electrode have as good optical and electrical properties as conventional a-Si:H photodiodes using ITO(indium tin oxide). Schottky barrier characteristics are also de-scribed.
Biogenic Hydroxylated Carboxylate Monomers Serve as Dispersants for Ceramic Particles
Authors: Ren Tao , Aksay I. A. , Yasrebi M. , Pellerin N. B. , Staley J. T. 
Published: March 2011

ABSTRACTA total of 20 biogenic carboxylic acids, which contain one to three negatively charged -COO−group(s), were investigated as dispersion additives in the processing of ceramic particles. Only carboxylic acids containing one or more hydroxyl groups were able to disperse α-A12O3particles in aqueous suspensions. Detailed studies of two carboxylic acids, citric acid and tricarballylic acid were undertaken: measurements of zeta potential, particle packing, and dispersant adsorption characeristics indicated that carboxylic acid groups and hydroxyl groups are both important for dispersion of the ceramic particles. Hydroxyl groups increased the adsorption of the molecules to the particles.
Supramolecular Engineering at Functionalized Surfaces
Authors: Knoll Wolfgang , Angermaier L. , Batz G. , Fritz T. , Furuno T. , Guder H.-J. , Hara M. , Liley M. , Niki K. , Spinke J. 
Published: March 2011

ABSTRACTThis contribution summarizes some strategies that we followed for the optimization of supramolecular architectures aiming at controlling the binding and organization of biopolymers at solid/solution-interfaces in a membrane-mimetic approach. The examples given concern mostly self-assembly processes and the biorecognition between biotin and streptavidin.
Chemoenzymatic Preparation of Sugar-Based Hydrogels
Authors: Rethwisch D. G. , Chen X. , Martin B. D. , Dordick J. S. 
Published: March 2011

ABSTRACTWe have prepared sugar-based hydrogels using a chemoenzymatic synthetic approach. Specifically, the regioselectivity of enzymes was used to prepare sugar acrylate monomers. These monomers were polymerized with a crosslinker in a standard free radical polymerization. The polymers consist of a polyacrylate backbone with sucrose, (α-methyl glucoside, or β-methyl galactoside pendant groups. These materials are highly water absorbent swelling to more than 100 times their initial weight when placed in water. The degree of swelling for poly(β-methyl galactoside 6-acrylate) hydrogel was relatively insensitive to pH (from pH 4.5-9) and ionic strength (0.15-3 M NaCl). Potential applications of these materials include waterabsorbents and drug delivery systems.
Second Harmonic Generation of Bacteriorhodopsin and its Application for Three-Dimensional Optical Memory
Authors: Chen Zhongping , Lewis A. , Kumart J. , Tripathy S. , Marxt K. , Akkarat J. , Kaplan D. 
Published: March 2011

ABSTRACTA novel three-dimensional optical memory system based on a light transducing protein, bacteriorhodopsin, is investigated. The system uses the nonlinear optical properties of bacteriorhodopsin to accomplish reading and writing operations. A nondestructive method of reading information in three-dimensional optical memory that uses second harmonic generation is demonstrated. This method has the advantage of fast speed, is nondestructive, and has the potential for parallel access.
Genetic Modified Bacteriorhodopsin for Holographic Interferometry
Authors: Hampp N. , Schmid R. , Zeisel D. 
Published: March 2011

ABSTRACTControlled modification of bacteriorhodopsin (BR) by means of genetic engineering is a powerful tool to create BR-variants with photophysical properties significantly different from the wildtype molecule and, in addition, adapted to the physical demands of various optical information processing techniques. The application of BR-films containing the variant D96N in real-time interferometry is described.