bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear Optical Properties of Buckminsterfullerene Solutions
Authors: Brandelik Donna , McLean Daniel , Schmitt Mark , Epling Bob , Colclasure Chris , Tondiglia Vince , Pachter Ruth , Obermeier Keith , Crane Robert L. 
Published: March 2011

ABSTRACTResults on the nonlinear properties of solutions of Buckminsterfullerene in toluene are reported. Optical limiting thresholds are as low as 15 mJ/cm2 with multiple pulse stability. Evidence for a different mechanism than that applicable in graphitic carbon black suspensions is presented. The calculated second hyperpolarizability agrees with experimentally reported values.
Interesting Electronic Properties Generated by Metal-Ion Linked C60 Chains
Authors: Singh D. J. , Fann Y. C. , Jansen S. A. 
Published: March 2011

ABSTRACTRecently it has been shown that buckminsterfullerene can be made to crystallize in a fee lattice when doped with various alkali metals eg. K, Rb, etc. Preliminary studies have shown the high propensity of C60 to be reduced without loss of stability. This may lead to interesting conductive pathways if a suitable dopant can be found which would act as an electronic “bridge” between adjacent “buckyballs” Out theoretical analyses have been geared towards a greater understanding of the reductive tendencies of C60, to discover how hypothetical metal-ion/C60, complexes differ from their corresponding simple, well characterized organometallic analogs. We demonstrate that the “metallocenium” link perturbs the electronic states of the C6 moiety including the frontier molecular Orbitals. Consequently, the metal ion plays an important role in establishing the electronic characteristics of metal-ion linked C60, chains and can be used to achieve desired properties.
Synthesis and Nonlinear Optical Characteristics of Chromophore-Functionalized Polymers Having Chromophore-Centered Hydrogen-Bonding and Crosslinking Groups
Authors: Jin Y. , Carr S. H. , Marks T. J. , Lin W. , Wong G. K. 
Published: March 2011

ABSTRACTIn this study, we report the synthesis and characterization of a new, systematically designed class of second-order NLO polymers in which the appended chromophoric substituent is modified (hydroxylated) to allow direct chromophore involvement in hydrogen-bonding and crosslinking. Thus, the glassy polymer poly(p-hydroxystyrene) has been functionalized to varying levels with the N-(3-hydroxy-4-nitrophenyl)-(S)-prolinoxy (HNPP) high-β chromophore. The time-dependent second harmonic generation characteristics of thin films of this material have been studied at λ = 1.064 μm as a function of chromophore functionalization level, hydrogen-bonding capacity, and thermal crosslinking. These materials are found to possess high d33 values (up to 34 × 10−9 esu) and long characteristic SHG decay times (longer than a year). Analysis of the decay of the second harmonic signal shows that increasing hydrogen-bonding density substantially increases relaxation times; it is further shown that introduction of crosslinks is yet more effective in imparting SHG temporal stability to these polymeric nonlinear optical materials.
Approaches from High-Spin Organic Molecules to Organic Ferromagnets
Authors: Ishida Takayuki , Inoue Katsuya , Koga Noboru , Nakamura Nobuo , Iwamura Hiizu 
Published: March 2011

ABSTRACTPseudo-two dimensional branched polycarbenes 1, 3, 5-[H(m-C6H4C:)n/3]3C6H3 (2)(n = 6, 9) were prepared. The measurement of their magnetization on a Faraday balance equipped with a light guide has revealed that 2(n = 6) has a tridecet ground state (S = 6.0). The m-phenylene skeleton as a dependable ferromagnetic coupling unit has also been applied with success to the synthesis of persistent systems, i.e., 5, by replacing each carbene center in linear polycarbenes 1 with a nitroxide. A necessary degree of steric protection of the radical centers was disclosed. Extension to real polymers 4 gave an only partly successful result.
Synthesis and Magnetic Characterization of Poly(2, 4-Bis(4, 4, 5, 5-Tetramethyl-4, 5-Dihydro-1H-Imidazolyl-1-OXY-3-Oxide-2-Phenoxy))Hexadiiyne
Authors: Zhang Deqing , Wu Peigi , Zhu Daoben 
Published: March 2011

ABSTRACTThe title monomer diacetylene with α-nitronyl nitroxide as pendants was synthesized and polymerized by heating in vacuum. The magnetic properties of the polymer were studied, and it was found that this organic polymer showed weak ferromagnetism.
Metallomesogens and Amorphous Metallopolymers: Magnetic Properties
Authors: Haase W. , Griesar K. , Erasmus-Buhr C. 
Published: March 2011

ABSTRACTThe magnetic susceptibility data in the temperature range of 4.2 K up to 300 K in the crystalline state of a metal lomesogen containing a Cu(II)-center are reported and discussed. Also magnetic properties of a Cu(II) containing chemically modified polymethylmethacrylate are presented. The interpretation of data, based on the Curie-Weiss-equation, shows a negative Weiss constant in the range up to θ = −27 K. An intermolecular long range antiferromagnetic exchange interaction at least in the solid or amorphous state has been discussed.
Syntheses and Properties of k-Phase Organic Superconductors
Authors: Hau Wang H. , Carlson K. D. , Geiser U. , Kini A. M. , Schultz A. J. , Williams J. M. , Welp U. , Darula K. E. , Hitsman V. M. , Lathrop M. W. , Megna L. A. , Mobley P. R. , Yaconi G. A. , Schirber J. E. , Overmyert D. L. 
Published: March 2011

ABSTRACTThe syntheses and physical properties of K-(ET)2CU[N(CN)2]X (X = Br and Cl) are summarized. The K-(ET)2Cu [N(CN)2] Br salt is the highest Tc radical-cation based ambient pressure organic superconductor (Tc = 11.6 K), and the K-(ET)2CU [N(CN)2] C1 salt becomes a superconductor at even higher Tc under 0.3 kbar hydrostatic pressure (Tc = 12.8 K). The similarities and differences between K-(ET)2Cu[N(CN)2]Br and K-(ET)2CU(NCS)2 (TC = 10.4 K) are presented. The X-ray structures at 127 K reveal that the S-S contacts shorten between ET dimers in the former compound while the S-S contacts shorten within dimers in the latter. The differences in their ESR linewidth behavior is also explained in terms of the structural differences. A semiconducting compound, (ET)Cu[N(CN)2]2, isolated during K-(ET)2Cu[N(CN)2]Cl synthesis is also reported. The ESR measurements of the K-(ET)2Cu[N(CN)2]Cl salt indicate that the phase transition near 40 K is similar to the spin density wave transition in (TMTSF)2SbF6. A new class of organic superconductors, K-(ET)2CU2(CN)3 and K-(ET)2Cu2(CN)3.δBrδ, is reported with Tc's of 2.8 K (1.5 kbar) and 2.6 K (1 kbar), respectively.
Superconducting Transition in к-Bedt-TTF Salts Under Magnetic Field
Authors: Ito Hiroshi , Nogami Yoshio , Watanabe Masashi , Ishiguro Takehiko , Komatsu Tokutaro , Saito Gunzi , Hosoito Nobuyoshi 
Published: March 2011

ABSTRACTThe superconducting transition under magnetic field for organic superconductors к-(BEDT-TTF)2 Cu(NCS)2 and к-(BEDT-TTFh)2 Cu[N(CN)2]Br has been analyzed by employing fluctuation renormal-ization theory. From magnetization measurements the interlayer and intralayer Ginzburg-Landau coherence lengths are determined. The effect of the isotope substitution to BEDT-TTF molecules has been studied. The result for resistive measurements is also described.
Tetraheterafulvalenes as Precursors of Conducting Materials
Authors: Papavassiliou George C. 
Published: March 2011

ABSTRACTMethods for preparation of thetraheterafulvalenes containig O, S, Se, N as additional he-teroatoms and some of their conducting products are described. Also, results concerning stoichi-ometry, structures, and physical properteis are briefly discussed.
The Synthesis and Physical Studies of a new Synthetic Metal: The Charge-Transfer Salt of Dimethyltetrathiotetracene-Tetracyanoethylene
Authors: Kilgore K. J. , Rath N. P. , Jones M. T. 
Published: March 2011

ABSTRACTThe 1:1 charge transfer salt of dimethyltetrathiotetracene (DMTTT) and of tetracyanoethylene (TCNE), C26H12N4S4 crystallizes from chlorobenzene in the monoclinic system, space group P2(l)/c with cell constants a = 11.136(2), b = 11.254(3), C = 17.280(4) A, beta = 96.56(2), V = 2151.4(9) A, Z = 4 and dcalc = 1.57 0 mg/nun. The structure is made up of dimers of DMTTT and TCNE, respectively. Polycrystalline samples of DMTTT/TCNE exhibit a weak paramagnetism which was studied by ESR techniques from 102 to 293 K. The ESR studies reveal anisotropie spectra which are best resolved in the temperature range 102 to 250 K. The spectra observed are those expected from a spin system which is described by an orthorhombic g-tensor. The isotropie g-value calculated from the observed anisotropie g-tensors falls between the isotropie g-values for DMTTT and TCNE. As the temperature is increased, the spectral width decreases suggesting motion of and/or an increase in the spin concentration. DMTTT/TCNE is a relatively poor electrical conductor which is consistent with its crystal structure.
Conducting and Superconducting Salts Based on Some Symmetrical and Unsymmetrical Donors
Authors: Papavassiliou George C. , Lagouvardos D. J. , Kakoussis V. C. , Terzis A. , Hountas A. , Hilti B. , Mayer C. , Zambounis J. S. , Pfeiffer J. , Whangbo M. -H. , Ren J. , Kang D. B. 
Published: March 2011

ABSTRACTConducting and superconducting salts based on bis(ethylenedithio)tetrathiafulvalene, ehtylenedithioselenatrithiafulvalene, ethylenedioxyethylenedithiotetrathiafulvalene, and ethylenedioxyvinylenedithiotetrathiafulvalene were prepared and studied.
Studies on the Chemical Modifications of Metallo- Organic Charge-Transfer Complex Switching and Memory Storage Materials
Authors: Ddan Hailing , Cohan Dwaine O. , Poehler Theodore O. 
Published: March 2011

ABSTRACTIn order to obtain desired switching and memory properties by carrying out chemical modifications on CuTCNQ-type charge-transfer complexes, systematic explorations on various donor and acceptor reactivities are necessary. Thus, the reactivities of thirty-three different metals with TCNQ and four organo-acceptors with Cu in an CH3CN solution were qualitatively studied, as well as the solvent effects on the complex film formation. Uniform coverage of Metallo-organic complex films were obtained (in the order of reactivities) on TCNQ complexes of Tl, Ca, Mg, Cu, Ag, Mn and Cd, as well as on Cu complexes of TCNQ(OET)2, BTCNQ and TCNQ(i-Pr)2. The donor reactivity is affected by its surface immunity (behavior) towards the acceptor attack and the solubility of the formed charge-transfer complex in the chosen solvent. The acceptor reactivity is affected mainly by a steric effect, followed by an inductive effect of the substituents. The complex film morphology and quality could be optimized by matching the relative reactivity of donor vs. acceptor and by choosing the appropriate solvent with proper solubility of the formed complex.
Polyaniline: Interrelationships Between Molecular Weight, Morphology, Donnan Potential and Conductivity
Authors: Macdiarmid Alan G. , Epstein Arthur J. 
Published: March 2011

ABSTRACTMethods for significantly increasing the molecular weight of polyaniline are described. The conductivity of doped polyaniline is shown to be more directly dependent on its degree of alignment/crystallinity than on its molecular weight. The tensile strength of polyanilines films and fibers increases with increasing stretch alignment. An interpenetrating polymer system involving polyaniline which shows greatly enhanced conductivity at pH values where polyaniline has negligible conductivity is described. The doping level of polyaniline is shown to be dependent not only on the pH of the dopant medium but also on the presence of dissolved neutral salts. This new phenomenon is explained in terms of Donnan equilibrium effects.
Diether Substituted Polyanilines: Novel Electrode Materials
Authors: Gopal J. , Vanhouten K. , Cowan D. O. , Poehler T. O. , Madsen P. V. , Searson P. C. 
Published: March 2011

ABSTRACT(2-Methoxy)ethoxy substituted anilines have been polymerized by chemical and electrochemical methods in hydrochloric acid (HC1) and p-toluenesulphonic acid(TsOH). Electrical conductivity, optical properties, solubility and charge capacity of these polymers are discussed.
Dynamics of Electrochromic Phenomena in Organic Conducting Polypyrrole Films
Authors: Amemiya T. , Hashimoto K. , Fujishima A. 
Published: March 2011

ABSTRACTThe electrochromic responses for two kinds of polypyrrole (PPy) films, PPy/inorganic anion and PPy/polyanion composite films, were studied by electromodulation technique. Analyses of electrical and optical responses show that electrochromic responses in conducting state were nearly the same for the both films, however, those in redox active state were characteristic of the two films. The differences in the responses of the two films seem to arise from the differences of both the morphologies of the films and charge transport properties in the films.
Towards Oriented Polymeric Structures for Cubic Nonlinear Optics
Authors: Lemoigne J. , Moroni M. , Coles H. , Thierry A. , Kajzar F. 
Published: March 2011

ABSTRACTOur approach consists of improving the molecular architecture of π-electron delocalization and orientations of the polymeric backbone of materials for cubic nonlinear optics. First, the syntheses of new polymers such as substituted polyacetylenes or polyphenyleneynylenes were done, in which the stiff conjugated chain and the flexible side-chains are well adapted to the orientation of the backbone. They have been studied for their third order susceptibility and their ability to give processable optical films. We have found liquid crystal properties with the rigid rod derivative of the poly(ethynylarylene). Unlike previous poly(ethynylarylene), we obtained a high molecular weight: , which allows films of good optical and mechanical properties. Second, in order to increase the third order response, we focused our attention on the orientational order of polydiacetylenes, which we obtained by epitaxial growth of the monomer on a single crystal substrate. From the proposed epitaxial model a possible extension of highly oriented thin films can be applied to a large class of materials.
Charge Carrier Generation by Exciton-Exciton Annihilation in Poly(Di-N-Hexylsilane)
Authors: Kepler R. G. , Soos Z. G. 
Published: March 2011

ABSTRACTWe have studied charge carrier generation by photons in thin films of poly(di-n-hexylsilane) over the photon energy range 3.15 to 6 eV and find that it is nonlinear in light intensity to above 4.5 eV. We show that the generation mechanism is exciton-exciton annihilation.
Recent Studies of Raman Spectroscopy of Polydiacetylene Crystals: Poly-Ipudo
Authors: Hankin S. H. W. , Sandman D. J. 
Published: March 2011

ABSTRACTUsing 632.8, 514.5, 488.0, and 457.9 nm as wavelengths of excitation, Raman spectra have been observed for single crystals of the polydiacetylene of - (CH2)4OCONHCH(CH3) 2 (Poly-IPUDO). The hysteresis effect observed for the thermochromic shift in the Raman spectra is supported by data from repetitive temperature cycling in differential scanning calorimetry.
Photoinduced Absorption Spectroscopy of Poly-3-Alkylthiophenes
Authors: Botta C. , Luzzati S. , Bolognesi A. , Tubino R. , Borghesi A. 
Published: March 2011

ABSTRACTWe report a study of the near infrared photoinduced absorption of a series of poly -3-decylthiophene with different supermolecular organization as solution cast films, good solvent and aggregated bad solvent solutions.Photoinduced subgap electronic states are detected both in the solid and in solutions independently from the presence of polymer aggregates. The study of the photoinduced activity Δ/T on the laser intensity I indicate a I0.6 dependence for the films and a I0.95 dependence for the solutions. This is the evidence that the photoinduced states are generated in the solid via an inter-chain mechanism while in the solution via an intra-chain mechanism.A possible role of the solvent into the photoexcitation pathway is discussed.
Synthesis and Characterization of Soluble Alkyl Substituted Poly(2, 5-Thienylene Vinylenes)
Authors: Catellani M. , Porzio W. , Musco A. , Pontellini R. 
Published: March 2011

ABSTRACTAlkyl substituted poly(2, 5-thienylenevinylene)s were produced with a new synthesis. The polymers are soluble and processable and show a strong electrochromic effect in the visible spectral range.
Defects in [1, 6-DI(N-Carbazolyl)-2, 4-Hexadiyne] Diacetylene Crystals
Authors: Liao Jun , Martin David C. 
Published: March 2011

ABSTRACTThe effect of solution concentration on the morphology of [l, 6-di(N-carbazolyl)-2, 4-hexadiyne] (DCHD) diacetylene crystals has been studied by conventional TEM, SAED, and HREM. Crystals obtained by evaporating 0.1 wt% DCHD-chloroform solution on amorphous carbon films are fibrous (about 3 μm wide and 100 μm long) and have defects such as kinks, pores, cracks, and dislocations. Two characteristic single crystal textured morphologies are found in these crystals: (1) a microfibrillar structure consisting of highly-oriented crystallites, with greater axial sizes than lateral sizes, slightly misorienting with a standard deviation of 3°; and (2) a“cross-hatched”structure consisting of highly-oriented crystalline domains separated by two groups of obliquely oriented boundary planes which make (45+/-3)∘ and (37+/-3)∘ angles respectively with the [001] chain direction. Crystals obtained by evaporating more dilute (0.01 wt%) DCHD-chloroform solutions onto amorphous carbon films are about 0.1–0.2 μm long and 0.05–0.1 μm wide and have the chain axis oriented perpendicular to the carbon support film. For these crystals, lateral-chain-invariant (LCI) small angle grain boundaries have been found in HREM images of the [001] zone axis.
Polarization Dependent Photocurrent in Thin Film Polydiacetylene Single Crystals
Authors: Yang Y. , Lee J. Y. , Li L. , Kumar J. , Jain A. K. , Tripathy S. K. , Matsuda H. , Okada S. , Nakanishi H. 
Published: March 2011

ABSTRACTThe photocurrent behavior in polydiacetylene (PDA) single crystals of PTS (poly-(2, 4-hexadiyne-1, 6-diol bis(p-toluenesulfonate)) and MADF (poly-(1-(3-(methylamino)phenyl)-4-(3, 5-bis (trifluoromethyl)-phenyl) butadiyne)) have been investigated by using steady state photoconductivity measurements. These measurements were carried out as a function of sample temperature and incident light polarization. PTS and MADF show completely different behavior in these measurements. These differences between PTS and MADF suggest that the side groups of PDA strongly influence the photocurrent behavior in PDA.
Mechanical and Electrical Properties of Heat-Treated Ladder Polymer Fiber
Authors: Wang C. S. , Lee C. Y-C , Arnold F. E. 
Published: March 2011

ABSTRACTThe ladder polymer poly[(7-oxo-7H, 10H-benz(d, e)imidazo(4', 5':5, 6)-benzimidazo(2, l-a)isoquinoline-3, 4:10, ll-tetrayl)-10-carbonyl] (BBL) was synthesized in polyphosphoric acid (PPA) at a concentration of 15% by weight. The polymer had an intrinsic viscosity of 8.75 dl/g in methanesulfonic acid (MSA) at 30°C. Highly oriented BBL fiber was spun by a dry-jet wet-spin process with a spin-draw-ratio of 8 to 1. After neutralization, the fiber exhibited a phosphoms content below the detectable limit (0.04%) by elemental analysis. This fiber, after a heat treatment at 300°C for 30 seconds under tension, showed a Young's modulus of 120 GPa, a tensile strength of 830 MPa and a compressive strength of 410 MPa. The fiber was also heat-treated at temperatures from 100°C to 600°C at 50°C increments for electrical conductivity measurements. It was found that room temperature DC conductivity of the BBL fiber increased dramatically from 2×10−8 S/cm with 100°C heat treatment to 3×10−4 S/cm with 350°C heat treatment and then decreased to 6×10−7 S/cm with 600°C heat treatment. The enhanced conductivity of heat-treated BBL fiber is believed due to the improved structural order in the BBL fiber and the thermally excited charge carriers.
Molecular Engineering of Polymers and Polymer Systems for Photonics and Electronics
Authors: Wegner Gerhard , Mathauer Klemens 
Published: March 2011

ABSTRACTRod-like polymers dressed with a skin of flexible short side-chains and overall cylindrical shape have been developed towards application in photonics and electronics. Layered structures which qualify as ‘molecular composites’ are obtained applying the Langmuir-Blodgett (LB) technique to these materials. The rod-like moieties are embedded in a continuous matrix formed by the side-chain segments. The orientation of the rods in the matrix is determined by the rheology of the LB-process. Photoreactive groups incorporated into the side-chain moieties allow photoresist patterns to be formed. The actual chemistry of the layer forming systems is based on poly(phthalocyaninatosiloxanes)s, helical poly(peptide)s, poly(silane)s or cellulose ethers. Some of the polymers have been designed to be chromophores for NLO processes or may serve as hosts for chromophores or ionophores.More complex architectures arise by preparation of structures with alternating layers of different chemical composition. The preparation of stripe wave guide patterns and of Si-based ion sensors is described.
Graded-Index and Single-Mode Polymer Optical Fibers
Authors: Koike Yasuhiro 
Published: March 2011

ABSTRACTHigh-bandwidth graded-index (GI) polymer optical fiber (POF) and single-mode POF with good mechanical properties were successfully obtained by our interfacial-gel polymerization technique. The bandwidth of the GI POF is about 1 GHz · km which is two hundred times larger than that of the conventional step-index (SI) POF. The minimum attenuation of transmission is 56 dB/km at 688-nm wavelength and 94 dB/km at 780-nm wavelength. The single-mode POF in which the core diameter was 3–15 μ m and the attenuation of transmission was 200 dB/km at 652-nm wavelength was successfully obtained for the first time.
New Strategies for Preparing Electrically Conductive Langmuir-Blodgett Films
Authors: Cheung J. H. , Rosner R. B. , Rubner M. F. 
Published: March 2011

ABSTRACTThe fabrication, structure and electrical properties of new electrically conductive Langmuir-Blodgett (LB) films of polyaniline and polypyrrole have been investigated. Polyaniline in its emeraldine-base form was mixed with stearic acid (PAN-B/SA) to produce stable films at the air-water interface (5/1 or 10/1 mole ratio of PAN-B/SA). These films were then transferred into multilayer films which were found to exhibit conductivities of about 1 S/cm upon doping with hydrochloric acid. The alkyl chains of the stearic acid molecules were found to be distributed randomly throughout the LB film thereby exerting a minimal influence on the electrical properties of the polyaniline phase. In addition to this mixed monolayer approach, a novel method of fabricating highly conductive polypyrrole LB films has been developed. This method is based on the sequential exposure of ferric stéarate LB films to hydrogen chloride (HC1) gas and pyrrole vapor. Each of these two solid state reactions was found to impart dramatic chemical and structural changes to the film. Polypyrrole LB films with conductivities as high as 5 S/cm were produced via this process. The electrical and optical properties of films made by both techniques were examined in order to elucidate their structure/property relationships.