bluuebunny/crossref_metadata_2025_split huggingface dataset:
All-Optical Switches and All-Optical Bistability by Nonlinear Optical Materials
Authors: Sasaki K. , Sasaki S. , Furukawa O. 
Published: March 2011

ABSTRACTAll-optical switches and all-optical bistabili ties are realized by waveguide structures with vacuum evaporated polydiacetylene(PDA) films. The basic structure of the all-optical switches are prepared in the form of layered waveguide directional coupler with vacuum evaporated PDA top layer. Clearly switchings are observed at 1064nm of pulsed Nd:YAG laser. Furthermore ultra-high speed switching with Ti;Safire 135fs laser are recognized.Operations of all-optical bistabilities are carried out by nonlinear coupling at grating structures in waveguides with PDA top layers. Hysterisis curves of bistability are affected by coupling parameters of gratings and parameters of waveguides.
Exact Optical Susceptibilities of Three State Systems Interacting with a Single Frequency Electric Field
Authors: Kavanaugh Theresa C. , Silbey Robert J. 
Published: March 2011

ABSTRACTUsing Floquet theory together with density matrix formalism, an exact, nonpertur-bative expression for the optical susceptibility of a three level system interacting with a single mode electric field is derived. By using a three state model that mimics a polymeric system, it is shown that in certain cases, using typical values for the intensity of the electric field, successive terms in the series χω=χ(1) + χ(3) E2… approach the same of order magnitude.
Damping and Third-Order Nonlinear Spectrum of Polyacetylene
Authors: Sun Xin , Fu Rong-Tang , Li Lie-Ming , Lin D. L. , George Thomas F. 
Published: March 2011

ABSTRACTExperiments have shown that the third-order nonlinear spectrum of trans- polyacetylene has two peaks at 0.6 eV and 0.9 eV respectively. None of the existing theories can give a quantitatively satisfying interpretation. A new theory is proposed in this paper by considering the excitation-dependent damping, and the theoretical results agree with the observed spectrum very well.
The Domain Mode in Ferroelectric Liquid Crystals a Novel Electrooptical Process
Authors: Beresnev L. A. , Pfeiffer M. , Ptkin S. A. , Haase W. 
Published: March 2011

ABSTRACTNovel electrooptical effects in ferroelectric liquid crystals with high spontaneous polarization (Ps ) are observed. They are connected with the formation of a modulated distribution of the macroscopic dipole moments of smectic layers if going along the layer normal. The period (D) of this modulation (ferroelectric domains) near the electrode surfaces (DS) and in the bulk (DB) of a FLC-specimen can differ appreciably, depending on an applied external voltage. The main role of the value of the effective spontaneous polarization is established. A variuos number of domain structures and corresponding diffraction patterns are observed under variation of frequency and amplitude of the external electric field. A simple explanation of the new electrooptical responses is proposed on the basis of interference and incommensurability of bulk and surface domains.
Photoconductivity in an Epoxy-Based Photocrosslinkable Nonlinear Optical Polymer
Authors: Li Lian , Jeng R. J. , Lee J. Y. , Yang Y. , Kumar J. , Tripathy S. K. 
Published: March 2011

ABSTRACTPhotoconductivity measurements on an epoxy-based photocrosslinkable second-order nonlinear optical (NLO) polymer - DGENC - NAC ( diglycidyl ether of nitrocatechol / nitroaniline prepolymer functionalized with cinnamoyl groups) are presented. Without introducing any sensitizer or charge carrier transport agents, large photoconductivity was obtained in this polymer system. Optical excitation of the NLO chromophores leads to photocarrier generation and it is conjectured that these NLO chromophores also play a role in the carrier transport. This polymer is one of the candidate materials for photorefraction.
Dielectric Study of a Photo-Ckosslinkable Nonlinear Optical Polymer
Authors: Chen J. I. , Moody R. A. , Chen Y. M. , Lee J. Y. , Sengupta S. K. , Kumar J. , Tripathy S. K. 
Published: March 2011

ABSTRACTTemperature and frequency dependent measurements are utilized to study the relaxation behavior of a photocrosslinking nonlinear optical (NLO) material based on a polyvinylcinnamate (PVCN) polymer matrix. 3-cinnamoyloxy-4-[4-(N, N-diethylamino)-2-cinnamoyloxy phenyl azo] nitrobenzene (CNNB-R) is used as a functionalized NLO active dye. Measurements of dielectric properties of PVCN doped with different levels of CNNB-R have been performed. NLO dye molecules were bonded to the host polymer by ultraviolet irradiation. Measurements were carried out from 50 to 200 °C and a frequency range of 30 Hz to 1 MHz. The effects of dye content and UV irradiation on the dielectric response are discussed.
Functionalizing C60 via Nucleophilic Trapping of its Radical Cations: 1. Alkoxylation and Arylation of C60; 2. Synthesis of Earmuff Ethers (Difulleroxyalkanes)
Authors: Miller Glen P. , Hsu Chang S. , Thomann Hans , Chiang Long Y. , Bernardo Marcelino 
Published: March 2011

ABSTRACTWhile its electrochemical oxidation is difficult, Cgg is readily oxidized in protic superacidic media. In order to exploit the reactive nature of the radical cations thus formed for the purpose of generating novel fullerene derivatives, a method involving nucleophilic trapping of oxidized Cgg has been developed. Thus, trapping oxidized Cgg with alcohols and aromatics results in the formation of alkoxylated and arylated C60, respectively, while trapping oxidized CgQ with x, y-diols results in the formation of x, y-difulleroxyalkanes (earmuff ethers).
Physical Properties of Superconducting and Ferromagnetic Materials Based on C60
Authors: Thompson J. D. , Sparn G. , Diederich F. , Grüner G. , Holczer K. , Kaner R. B. , Whetten R. L. , Allemand P.-M. , Li Q. , Wudl F. 
Published: March 2011

ABSTRACTWe present results of magnetization and pressure measurements on recently discovered superconductors K3C60 and Rb3C60. as well as ferromagnetic C60TDAE, and discuss the nature of the ground state suggested by these studies.
Defective Buckyballs: Alternative Structural Isomers of C60
Authors: Raghavachari Krishnan , Rohlfing Celeste M. 
Published: March 2011

ABSTRACTAlternative isomerie structures of C60 spheroids have been investigated using semiempirical and ab initio quantum chemical techniques. Unlike the icosahedral ground state, these isomers are characterized by the presence of pentagonal rings adjacent to each other. The lowest energy alternative isomer of C60 has two such pairs of edge-sharing pentagons and lies = 2 eV higher in energy than the ground state. Isomers containing three and four pairs of adjacent pentagons have also been studied in detail. Overall, the energy contributions of these adjacent pentagonal defects are additive, with each defect making the structure less stable by = 1 eV.
Raman Scattering in MxC60 Films (M=K. Rb, Cs; ×=0, 3.6)
Authors: Wang Kai-An , Zhou Ping , Wang Ying , Holden J. M. , Ren Song-Mn , Hager G. T. , Ni H. F. , Eklund P. C. , Dresselhaus G. , Dresselhaus M. S. 
Published: March 2011

ABSTRACTThe Raman-active modes of solid films of MxC60 (x-0, 6; M=K, Rb, Cs) and K3C60 have been studied experimentally. The mode-activity is dominated by intraball interactions, and the effect of the M + ions on the C60 spectrum is observed to be almost insensitive to the radius or mass of the alkali metal. Tangential modes of solid C60 are observed to soften in M660 by -60 cm−1, which can be attributed to a charge-transfer-induced elongation of the intraball bond lengths, similar to that observed in graphite intercalation compounds. Conversely, the radial modes are found to upshift slightly, indicating that a competing mechanism counteracts the effect of the bond elongation. For K3C60, six Raman lines have been observed in which the lowest frequency mode exhibits a Breit-Wigner-Fano lineshape, indicating a coupling between the lowest frequency Hq-derived intramolecular modes of C60 and a broad Raman-active continuum with the same symmetry lying lower in frequency.
In Situ Photoconductive Study of C60 and Phthalocyanine Thin Films
Authors: Minami Nobutsugu 
Published: March 2011

ABSTRACTThe in situ measurement of lateral photoconductivity has been carried out on vacuum vapor deposited C60 and phthalocyanine thin films. From the photo-current increase curve during the deposition and the SEM observation of copper phthalocyanine (CuPc) thin films, it has been revealed that, at an early stage of deposition, they consist of small clusters scattered on substrate. As the thickness Increases, the clusters coalesce to eventually form continuous film. We also show that C60 thin film has considerable photoconductivity. The photo-current spectrum agrees well with the absorption one with the exception that a peak at 600 nm appears only in the former. This wavelength region corresponds to a theoretically predicted forbidden transition. An onset of photocurrent at 760 nm is assigned to the absorption edge of solid C60. The photoconductivity of C60 thin films shows a rather unusual temperature dependence In that a small drop of temperature (e.g. from 25° C to 15° C) causes a dramatic increase In photocurrent by more than two orders of magnitude.
Ferro-and Antiferromagnetic Behaviors of Some Organomatallic and Coordinated Compounds
Authors: Wei H. H. , Chang Y. F. 
Published: March 2011

ABSTRACTSeveral new examples of ferro- and antiferromagnetic organometallic and coordinated compounds have been investigated by means of the temperature-dependent magnetic measurements and Mössbauer spectroscopy. Above 70 K the Cu3 [Fe(CN)6] 2-4H2O compound is ferromagnetic as it obeys the Curie-Weiss experession, χm= C/(T-θ), with θ = 25 K; μeff evalued at 200 K is 4.91 μβ. Below 20 K this compound displays the onset of spontaneous magnetization in zero applied field. Above 10 K the Cu[(bpy>2] 3 [Fe(CN)6] 2.5H2O is also ferromagnetic (θ= 2.5 K). Above 20 K the antiferromagnetic [Fe(C5H4Me)2] + [TCNOJ- (θ= 3.25 K) and [Fe(C5H4Me)2]+[TCNE]- (θ= -3.64 K) obey the Curie-Weiss expression. The e.p.r. and Mössbauer spectra for these compounds have been discussed.
Design of Organic Superconductors Based on Bedt-TTF
Authors: Saito Gunzi , Komatsu Tokutaro , Nakamura Toshikazu , Yamochi Hideki 
Published: March 2011

ABSTRACTA close examination of the relation between Tc and structural characteristics of BEDT-TTF superconductors has revealed that there is a good correlation between the effective volume (VeffαVc-Vanion and Tc but no such correlation between the unit cell volume (Vc) and Tc. In order to increase Veff, it is favorable to use big but thin anion which can form a thin two-dimensional anion layer. Three-dimensional donor interactions are critical to have sizable Tc. According to the designing, two new superconductors; K-(BEDT-TTF)2CuCN[N(CN)2] (Tc=11.2K) and K'-(BEDT-TTF)2Cu2(CN)3 (Tc=3.8K), are prepared and their physical and structural properties are described. Their Tc's are discussed in terms of veff.
Cation Radical Salts of S, S-Dmbedt-TTF: Semiconductors, Metals and a new Organic Superconductor
Authors: Zambounis John S. , Mayer Carl W. , Hauenstein Kurt , Htjlti Bruno , Hofherr Walther , Pfeiffer Jürgen , Bürkle Markus , Rihs Grety 
Published: March 2011

ABSTRACTThe electrical properties of cation-radical salts based on S, S-DMBEDT-TTF and their crystal structures are presented.
Fermi Surface Study of Organic Metals (Bedt-TTF)2X
Authors: Tokumoto M. , Swanson A. G. , Brooks J. S. , Agosta C. C. , Hannahs S. T. , Kinoshita N. , Anzai H. , Tamura M. , Tajima H. , Kuroda H. , Ugawa A. , Yakushi K. 
Published: March 2011

ABSTRACTObservations of Shubnikov-de Haas(SdH) and de Haas-van Alphen(dHvA) oscillations in organic metals (BEDT-TTF)2X, with X=KHg(SCN)4, θ-I3 and β″-AuBr2. are reported. In KHg(SCN)4 salt, in addition to the SdH oscillations with fundamental frequency of 670 T corresponding to about 16% of the first Brillouin zone(FBZ), we observed splitting of each SdH peak which we ascribed to “spin-splitting” We have also found that the ground state of this salt is not a simple metal but has some magnetic character. In θ-l3 salt we have succeeded in an observation of dHvA oscillations for the first time. We observed a “saw-tooth” dHvA oscillation characteristic to a highly two-dimensional and extraordinary clean electronic system. In addition to the fundamental frequency of 4170 T corresponding to 50.4 % of the FBZ and its higher harmonics, we observed an oscillation with lower frequency of 730 T corresponding to about 8.8 % of the FBZ. A new Fermi surface topology for θ-l3 salt is proposed based on the analysis of the dHvA effect. In β″-AuBr2, we observed complex dHvA oscillations, which can be explained in terms of the mixing of two fundamental frequencies of 47 and 268 T, suggesting the presence of very small pockets corresponding to 0.6 and 2.9 % of the FBZ.
Synthesis and Physical Properties of two Organic Donor Derivatives of 12-Molybdophosphate Anion [PMO12O40] n-: New Examples of Mixed-Valence Organic Donor-Inorganic Acceptor Compounds
Authors: Attanasio D. , Bellitto C. , Bonamico M. , Righini G. , Staulo G. 
Published: March 2011

ABSTRACTTetrathiafulvalene and bis(ethylenedithio)tetrathiaful-valene radical-cation salts of the a-Keggin anion [PMo12O40] have been synthesized and characterized. They both are mixed-valence compounds and contain the paramagnetic anion [PMO12O40] 4-. The former contains irregular TTF ϱ+ chains isolated by the inorganic anions. From the IR spectrum a ϱ=+0.5 is suggested. The latter is two-dimensional, where BEDT-TTF molecules are ionised, ϱ=+0.5, and arranged in irregular chains. They show electrical conductivity typical of organic semiconductors.
Energy Band Structure for Metallic Polyacetylene
Authors: Tanaka Chizuko , Tanaka Jiro 
Published: March 2011

ABSTRACTThe optimized molecular structures of doped polyacetylene model compounds are studied by the ab initio SCF MO method. The calculated structures are assigned to polaron, charged soliton and poison unit. The one dimensional energy band structures of the charged soliton-antisoliton and the polson-antipolson lattices are investigated. The latter one gives a quasi-metallic energy band. The results of the energy band calculation are consistent with the electrical properties and ultraviolet photoemission spectra of the doped polyacetylene.
Highly Conducting and Thermally Stable Conjugated Polymers
Authors: Jen Alex K-Y. , Drzewinski Michael , Chin Hui Hwui , Boara Guilio 
Published: March 2011

ABSTRACTA series of highly conductive, environmentally and thermally stable polyanilines was synthesized. These polymers, which are obtained by employing careful synthetic conditions, purification procedures, and dopant variations, show interesting morphological structures and high temperature stability. Thermal studies by TGA, DSC and DMTA show a glass transition temperature (Tg) for neutral polyaniline around 185°C. This is the same temperature at which the conductivity and crystallinity decrease. Isothermal heatings of the polyaniline tosylate at 200 and 250°C in air show significant amounts of weight loss. This is due to dopant loss through irreversible chain rearrangements and air oxidation at temperatures above Tg.
In-Situ Monitoring of the Kinetics and Mechanism of Conducting Polymer Synthesis
Authors: Fong Yoke , Chen Chengbo , Schlenoff Joseph B. 
Published: March 2011

ABSTRACTThe aqueous polymerization of pyrrole and aniline by ferricyanide and persulfate, respectively, was monitored by Raman scattering and potentiometry. Raman scattering gave well-resolved signals for monomer and oxidizer. The kinetics of polypyrrole formation could be determined by both techniques, whereas only Raman scattering was suitable for the aniline system. The stoichiometry of the pyrrole polymerization remained constant at 2.5 oxidant molecules per pyrrole consumed. The aniline reaction showed an accelerated region with aniline consumption lagging persulfate use.
Electrically Conductive Composite of Polypyrrole and Liquid Crystalline Aromatic Copolyamide
Authors: Bao Jing-Sheng , Xu C. C. , Cai W. , Bi Xian-Tong 
Published: March 2011

ABSTRACTThe modification of the mechanical properties of polypyrrole(PPy) by electrochemical preparation of conductive composite film from pyrrole(Py) and two kinds of liquid crystalline copolyamide of poly(p-phenylene-terephthal- amide)(PPTA) poly(p-phenyleneterephthalamide/diphenyl ether terephthal- amide) (PPTA[0]) and poly(p-phenyleneterephthalamide/diphenyl methane tere-phthalamide) (PPTA[C]) are presented.The electrical conductivity of the PPTA[0]/PPy and PPTA[C]/PPy composites are the same order of magnitude as PPy or PPTA/PPy. The mechanical properties of the composite films are better than that of pure PPy. and the composite films have good electroactivlty and thermalstability.
Structure and Morphology of Metallic-Conductive Polyacetylene
Authors: Tsukamoto Jun , Takahashi Akio 
Published: March 2011

ABSTRACTWe have carried out structural analyses of highly conductive polyacetylene in order to elucidate the relationship between stucture and electrical properties. Sharp X-ray diffraction lines were observed for the heavily iodine-doped polyacetylene showing high conductivity, in contrast with the diffused diffractions of the conventional one. SEM observation reveals that granular structure of the new polyacetylene is composed of densely packed micro-fibrils. The result from the resonance Raman analysis indicates that the new cis-polyacetylene contains more longer conjugated segments than conventional polyacetylene. The relationship between the structure and conductivity is discussed, basing on the crystal structure and morphology observed.
Ion Implantation of Conducting Ladder and Rigid-Rod Polymers
Authors: Bums A. , Wang Z. H. , Du G. , Joo J. , Epstein A. J. , Osaheni J. A. , Jenekhe S. A. , Wang C. S. 
Published: March 2011

ABSTRACTWe report optical, thermal, and transport studies on Kr+ implanted ladder (BBL) and rigid-rod ( PBO and PBZT) polymers, with an ion energy of 200 keV and dosage of 4 × 1016 / cm2. Both pristine and ion implanted polymers were studied using X-ray photo-electron spectroscopy (XPS), optical spectroscopy (IR and UV-Vis), thermogravimetric analysis (TGA), and temperature dependent DC conductivity (σ(T)). The XPS and IR results show a reduction in the heteroatoms and increase in the relative carbon content. After ion implantation, each polymer had a similar electronic structure, showing broad band metallic behavior. TGA data shows that each implanted polymer retains its thermal stability. σ(T) of the implanted polymers has the weakest temperature dependence of any conducting polymer reported, in accord with a disordered metal.
Multiphoton Spectra of Conjugated Polymers
Authors: Soos Z. G. , Etemad S. , Kepler R. G. 
Published: March 2011

ABSTRACTMultiphoton excitations of conjugated polymers are related to their optical gap, Eg, which serves as an internal standard. In π-electron models with electron-hole symmetry, the alternation gap Ea is the lowest-energy two-photon absorption (TPA) and increases with the alternation δ of the transfer integrals t(l ± δ) along the backbone. Increasing electron-electron (e-e) correlations shift an intense TPA from 2Eg in the band limit to Eg in the atomic limit. Two-photon spectra and multiphoton resonances in polyenes, polydiacetylenes, and polysilanes are related to interacting electrons in Pariser-Parr-Pople(PPP) models with increasing alternation and either carbon or silicon e-e interactions. Some general features of correlated states of conjugated polymers are discussed in the rigid-lattice limit.
Unusual X-Ray Diffraction Vector Shift Observed in Heterogeneous Langmuir-Blodgett Multilayer Films
Authors: Nogami Yoshio , Ogasawara Kazuyoshi , Takeuchi Shigeki , Ishiguro Takehiko , Ohsumi Kazumasa , Shimizugawa Yutaka 
Published: March 2011

ABSTRACTStacking of heterogeneous Langmuir-Blodgett films was studied by high resolution X-ray diffraction method using synchrotron radiation (SR) source. The diffraction patterns of the heterogeneous films formed with alternately deposited Cd salts of fatty acids with different length of alkyl chains exhibit anomalous oscillatory structure in diffraction vector.
Plasma Activated Chemical Vapor Deposition of Polythiophene Thin Films
Authors: Targove J. D. , Haaland P. D. , Kutsche C. A. 
Published: March 2011

ABSTRACTPolythiophene thin films have been deposited by a novel plasma technique which avoids the disadvantages of conventional plasma-based processes. In particular, the thiophene precursor is injected into an activated argon stream rather than into a plasma. The films produced are dense and uniform, with surface roughness of less than 1 nm. Other film properties are comparable to films deposited by more conventional methods. These films have been processed by reactive ion etching to produce micron-scale features.
Deuelopment of a Computer Program for the Determination of Opticrl Constants of Radiation Damaged Optical Elements Using Classical Oscillator Fit to Reflectance and/or Trrnsmittrnce Data
Authors: Rahman Miftahur , Yang C. , Chiu K. S. , Karakashian A. S. , Karp C. , Mooney T. , Al-Jumaily G. 
Published: March 2011

ARSTAACTA computer program is developed using the classical oscillator model of Hans W. Verleur [1] to study the transmittance and reflectance spectra of pre- and post radiation damaged optical components such as color glass filters, multilayer bandpass filters and band reject filters irradiated by one megárad gamma radiation from a 60Co source. In the classical oscillator model, the complex dielectric constant ε(ω) is represented as the sum of classical oscillators with oscillator strength Si, resonance frequency ωi, linewidth Γi and high frequency dielectric constant ε∞ which are the adjustable parameters to fit the experimental transmittance and reflectance data over a limited range of frequency. The parameters have physical significance in the lattice vibrational region. In the spectral regions corresponding to electronic transitions, the spectra can be fitted accurately with no physical meaning associated with the parameters. The present work has concentrated on the calculations of the optical constants n and k of the radiation damaged optical components to determine the effects of 60Co gamma radiation on the optical constants of both films and substrates in these components.
Chemical Vapor Deposition Modeling for High Temperature Materials
Authors: Gokoglu Suleynaz A. 
Published: March 2011

AbstractThe formalism for the accurate modeling of chemical vapor deposition (CVD) processes has matured based on the well established principles of transport phenomena and chemical kinetics in the gas phase and on surfaces. The utility and limitations of such models are discussed in practical applications for high temperature structural materials. Attention is drawn to the complexities and uncertainties in chemical kinetics. Traditional approaches based on only equilibrium thermochemistry and/or transport phenomena are defended as useful tools, within their validity, for engineering purposes. The role of modeling is discussed within the context of establishing the link between CVD process parameters and material microstructures/ properties. It is argued that CVD modeling is an essential part of designing CVD equipment and controlling/optimizing CVD processes for the production and/or coating of high performance structural materials.