bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Stability of TiSi2 on High Dose Ion Implanted Silicon
Authors: Chen J.F. , Chen L.J. , Lur W. 
Published: March 2011

ABSTRACTThermal stability of TiSi2 on blank, high–dose BF2+–, B+–, F+–, As+–, and P+–implanted silicon has been studied by both cross–sectional and plan–view transmission electron microscopy as well as by sheet resistance measurements. The surface morphology of TiSi2 was found to be significantly influenced by the implantation in silicon substrate.Simultaneous presence of B and F was found to be most effective in stabilizing the TiSi2 thin films. Sheet resistance data were found to correlate well with the morphological and microstructural observation. The mechanisms for the stabilization of silicide films are discussed.
Pulsed Excimer Laser Photoablation by Backside Irradiation of Thin Metal Coated Polymer Films
Authors: Lätsch Stefan , Hiraoka Hiroyuki 
Published: March 2011

AbstractBackside laser irradiation of metal coated quartz wafers can be used for transferring material imagewise to a target cleanly in absence of chemical vapors. However, the transfer of metal from a quartz surface requires a high energy, resulting in poor quality images in some cases.Use of a fluorinated polymer layer between the polycarbonate substrate and a Te-Se metal alloy is known for clean fabrication of metal holes in write-once-read-only memory media. Polymer thin films can be used similarly in backside laser irradiation for metal ejection from substrate surfaces.With an ArF excimer laser at 193 nm, gold and aluminum were ejected imagewise from Teflon AF, poly(methacrylonitrile) and quartz surfaces. The threshold fluences of 230 Å thick gold films from polymer surfaces were 7.9 to 9.7 mJ/cm2, whereas the threshold fluence from a quartz surface was determined to be 17.8 mJ/cm2. For aluminum on top of quartz and aluminum coated polymers, higher threshold fluences were found compared to gold ranging from 12.96 to 22.7 mJ/cm2.Also, interfacial reactions between the polymer films and the metal layer occured and have been studied by SEM and XPS.
Molecular Dynamics Study of the Influence of Specific Interactions on the Structure and Properties of the Interphase
Authors: Maguire John F. , Lupkowski Mark 
Published: March 2011

AbstractSince the interphase plays an important role in the strength and durability of a bondline, it is essential to develop a fundamental understanding of the interphasal region in order to predict and control its structure and properties. Therefore, a key aspect to consider it's the influence of specific chemical interactions on the evolution of the structure of the interphase. Surface analysis techniques have been very effective in studying this problem. However, such experimental approaches do not yet have the specificity and resolution to obtain the atomic densities as a function of distance from the surface. In this work we employ molecular dynamics calculations to study adsorption of both monomers and polymer networks. The density profiles, molecular structure, and mobility of epoxy, amine, and polymer networks on the surfaces of graphite and alumina have been examined. We have considered the influence of changes in surface chemistry on the interfacial structure of the adsorbed species. For all systems investigated the presence of a surface resulted in pronounced ordering of atomic species in the near surface region. Specific chemical interactions such as hydrogen bonding further enhance this tendency and leads to near-surface structure which is markedly different from the bulk.
Metal Overlayers on Self-Organized Molecular Assemblies: X-ray Photoelectron Spectroscopy of CR/CM and NI/CM on 12-Nercaptododecanenitrile
Authors: Jung D. R. , Czanderna A. W. 
Published: March 2011

AbstractOverlayers of Cr and Ni deposited at 22 °C and at -100 °C onto self-organized molecular assemblies of HS(CH2 )11 CN on Au have been studied by X-ray photoelectron spectroscopy (XPS). For the lowest overlayer coverages, the C ls and N is core levels show evidence for a chemical interaction between the deposited metal and the CN end-group. At 22 °C and for coverages of 0.6 nm or more, Cr/CN shows a C ls low binding energy, carbide-like shoulder. The degree of metal penetration is assessed based on the attenuation of the C ls and Au 4f intensities, and on the positions of the Cr and Ni 2p levels. In general, the least penetration and the largest binding energy shifts of the C, N, and the Cr or Ni core levels are observed for Cr/CN, while and Ni/CN shows smaller shifts and greater penetration.
Chemical grafting of silane end-functionalized polymer on silicon surfaces
Authors: Karim A , Satija S. K. , Orts W. , Ankner J. F. , Majkrzak C. F. , Fetters L. J. 
Published: March 2011

AbstractX-ray and neutron reflectivity was used to determine the kinetics of adsorption and characterize the concentration profile of a low molecular weight trichlorosilane endfunctionalized polystyrene adsorbed onto polished silicon wafers. Higher adsorbed amounts were obtained from a cyclohexane solution of the polymer rather than toluene, with kinetics that followed a stretched exponential behavior. For moderately high grafting densities the polymer concentration profile in deuterated toluene (a good solvent) was best modelled using a small tailed parabola. In deuterated cyclohexane (a poor solvent) the brush profile steepened but was substantially smoother than a step, while in D20 (a non-solvent) it became step-like.
Modification of the Interface between Paints and Stainless Steels by Means of an Interphase of Crosslinked Organofunctional Silanes
Authors: Ooij Wim J. Van , Sabata Ashok 
Published: March 2011

AbstractThe adhesion of paint systems to stainless steel substrates can be markedly improved by a pretreatment using organofunctional silanes. The paint-metal interface thus obtained can be made more resistant to corrosive attack by adding a silane crosslinker to the hydrolyzed silane solution. The films formed on the metal surface were characterized by Time-of-Flight Secondary Ion Mass Spectrometry (TOFSIMS).
Plasma Polymerization of Fluorocarbon Thin Films on Glass and Metal Substrates
Authors: O'Keefe M. J. , Rigsbee J. M. 
Published: March 2011

AbstractPlasma polymerization of thin, fluorocarbon films onto glass, low carbon steel, and aluminium foil substrates using a hexafluoroethane (C2F6) glow discharge in a parallel plate, rf-sputter system was studied. Continuous, 100 nm thick fluoropolymer films were obtained when a graphite sputter target was used as the cathode material. Depositions conducted without the use of a consumable cathode produce continuous but thin (<10 nm) films of fluorocarbon material. Analysis of the plasma by optical emission spectroscopy determined that the dominant species in the discharge was CF2 for both target configurations. An increase in the intensity of specific CF2 transitions was observed when the graphite target was used. Characterization of the deposited films by X-ray photoelectron spectroscopy of the C 1s and F 1s photoelectrons was used to determine the atomic F/C ratio and distribution of CF3, CF2, CF, C-CF, and C binding states. Films fabricated with the graphite target had a lower F/C ratio than depositions made without a consumable target. However, the distribution of binding states and the F/C ratio in the fluoropolymer was dependent on the substrate material. The results of the study indicate that the fluoropolymer film composition was significantly influenced by the underlying substrate material.
Hydrogen Peroxide-Sensitive Electrode Based on Supported Bilayer Lipid Membrane
Authors: Liu W. , Ottova-Leitmannova A. , Tien H. T. 
Published: March 2011

AbstractSupported bilayer lipid membrane (s-BLM) is a new type of self-assembled membranes. In this paper, the s-BiMs were formed on the tips of the freshly cut Teflon-coated stainless steel wires. The sensitivity of s-Bills to Haca was studied by current and potential measurements. We also investigated the effects of TCNQ and DP-TrF modifiers on the H2O2 response of the s-BLM systems. It was found that DP-TTF molecules can improve the stability of the s-BLM and its sensitivity range to H2O2. Further, the cyclic voltammetric behaviors of the s-Bill systems were studied as a function of H2O2 concentration.
Characterization of Polymers and Their Surfaces Using Ultra-Soft X-Ray Absorption Spectroscopy
Authors: Mitchell Gary E. , Dekoven Benjamin M. , Speth David R. , Jones Mark E. , Curphy James J. , Schmidt Donald L. , Yeh Alvin T. , Gland John L. , Fischer Daniel A. 
Published: March 2011

AbstractIn this paper we illustrate the use of Ultra Soft X-ray Absorption Spectroscopy (USXAS) for the characterization of polymeric materials by highlighting three novel applications of the technique. The surface sensitivity of electron yield (3 nm) and the bulk information available from fluorescence yield USXAS (200 nm) provide unique information on the chemistry of polymer surfaces and interfaces. USXAS is sensitive to both concentration and orientation of functional groups in polymers. The systems highlighted here include the characterization of flame treated model acrylic automotive coatings, ultra-low surface energy crosslinked fluorocarbon films, and spin cast polystyrene films. The chemical and surface sensitivity of the technique are emphasized by the ability of USXAS to detect an increase in the trigonally coordinated carbon at the surface after treatment with a reducing flame. The sensitivity to functional group orientation at the surface is demonstrated by the characterization of the crosslinked flurocarbon polymer films. The results show that the pendant fluoroalkyl moieties of these polymers are strongly oriented perpendicular to the film surface. Spin coated polystyrene films were characterized as a functionv of molecular weight, film thickness and casting solvent. The pendant phenyl groups were found to be preferentially oriented towards the normal to the surface plane, independent of casting solvent, molecular weight, and film thickness
Metal-Polymer Interphases in Structural Adhesive Joints
Authors: Davis G. D. 
Published: March 2011

AbstractHigh-performance structural adhesive joints, such as those found in aerospace components, must exhibit both high initial strength and excellent durability in severe environments. These properties are largely governed by the bonding across and the stability of the metal (oxide) - polymer interphase. Modern adherend surface treatments commonly provide the required adequate strength and durability. Factors that can degrade or limit joint strength and durability are discussed along with means to improve or, at least, to prevent reduction of these properties. Finally, areas in which advances are needed: increased understanding of bonding phenomena, improved reliability of bonded joints, and minimized environmental burdens are suggested.
Influence of Polymer Coatings and Adhesion on the Mechanical Strength, Fatigue and Aging of Optical Fibers
Authors: Inniss D. , Shepherd L. , Brownlow D. L. , Zhong Q. 
Published: March 2011

AbstractThe influence of polymer coatings on the mechanical properties of optical fibers is reviewed. Current research is directed at the chemical mechanisms that contribute to mechanical strength degradation. In this review, a chemical kinetics model is applied to describe the influence of polymer adhesion on chemical corrosion of the glass fiber (i.e., its zero stress and stress assisted corrosion).
Conductive Polymer / High-Tc Superconductor Assemblies
Authors: McDevitt John T. , Haupt Steven G. , Riley David R. , Zhao Jianai , Jones Christopher T. 
Published: March 2011

AbstractThe preparation of a hybrid conducting polymer/high-temperature superconductor device consisting of a polypyrrole coated YBa2Cu3O7-δ microbridge is reported. Electrochemical techniques are exploited to alter the oxidation state of the polymer and, in doing so, it is found for the first time that superconductivity can be modulated in a controllable and reproducible fashion by a polymer layer. Whereas the neutral (insulating) polypyrrole only slightly influences the electrical properties of the underlying YBa2Cu3O7-δ film, the oxidized (conductive) polymer depresses Tc by up to 15K. Thus, a new type of molecular switch for controlling superconductivity is demonstrated.
The Effect of Crosslink Density and Complex Fields of Stresses on the Network Chain Mobility of Model Epoxy Resins
Authors: Bron Samuel , Katz Dov 
Published: March 2011

AbstractThe viscoelastic properties of model epoxy resins were investigated using a tensile stress relaxation technique. Simultaneously with the applied tensile strain, the specimens were subjected to torsional oscillations in a specially designed instrument. The crosslinking density of the resins was controlled by the length of the aliphatic chain of the diamine hardener. Smooth master curves were obtained by Computed Aided Superposition (CAS) using a software written especially for this work. The shape of the master curves changed significantly as a function of the frequency of torsional oscillations. Based on previously published data, as well as on pertinent information from literature, it was concluded that the variations in the shape of the master curves reflect corresponding changes in the spectrum of relaxation times of the investigated resins. It is suggested that the observed phenomena are caused by physical processes, such as short-range orientation and physical aging, which lead to densification of the network and a corresponding increase in its stiffness.
Titanium Deposition on Polymer Surfaces: An Xps Study
Authors: Konstadinidis K. , Opila R. L. , Taylor J. A. , Miller A. C. 
Published: March 2011

AbstractWe have used X-ray Photoelectron Spectroscopy to study the chemical interactions at the interface formed during in situ deposition of Ti atoms on triazine, polyimide (PMDAODA), and polystyrene surfaces. For deposition on thin triazine films (∼ 100Å) we observe that titanium carbide is the dominant product, while oxides and nitrides are formed as well. Aging in air causes the carbide and nitride to convert to the more thermodynamically stable oxide. Titanium carbide is also the primary species at the Ti/polyimide and Ti/polystyrene interface. In all cases the reaction of Ti atoms with different sites in the polymer is nonselective.
Thermal Conductivity of Single Carbon Fibers Using Photothermal Deflection Techniques
Authors: Barkyoumb J. H. , Land D. J. , Kidder J. N. 
Published: March 2011

AbstractA modification of the transverse photothermal deflection technique is used to determine the thermal diffusivity of high-conductivity carbon fibers. A chopped, cw Ar-ion laser beam is focused to a point on the fiber to cause localized heating of the fiber and the surrounding transparent fluid medium. The fluid medium immediately adjacent to the fiber sample is probed with a weak He-Ne laser that grazes the fiber surface and is deflected by the synchronous thermal lens produced near the fiber surface. The pump laser is stepped along the length of the fiber to produce a photothermal signal that is proportional to the temperature gradient along the length of the fiber. The theory necessary to predict the magnitude and phase of the probe beam deflection as a function of distance along the fiber is derived. This signal can then be analyzed by a simple method to determine the thermal diffusivity of the carbon fiber.
Synthetic Fibres for Fibre Concrete Composites
Authors: Feldman Dorel , Zheng Zhihong 
Published: March 2011

AbstractThe use of fibrous reinforcement to improve the strength and deformation properties of concrete is now well established. The concept of fibre reinforcement is to use the deformation of the matrix under stress to transfer load to the fibre. Substantial improvements in static and dynamic strength properties could then be achieved if the fibres are strong and stiff, and loaded to fracture, provided there is, of course, a minimum fibre-volume fraction.Besides fibres like asbestos, glass and steel, different kind of synthetic fibres such as polyethylene, polypropylene, polyamide and others are recently used for cementitious composites.Together with general aspects of synthetic fibre concrete composites, original results concerning the study done on a hybrid composite based on steel and polypropylene fibres will be presented and discussed.
The Relationship Between Morphology and Esc in Thermoplastic Toughened Phenolics
Authors: Eccott A. R. , Arnold J. C. , Isaac D. H. 
Published: March 2011

AbstractA detailed investigation has been performed to relate the environmental stress cracking (ESC) behaviour of thermoplastic toughened phenolic materials to their morphology. Within the range of added thermoplastic studied (0 to 35%), two scales of morphology were seen to occur. In addition to a small scale interpenetrating network, there exists a larger scale morphology formed from “seas” of excess and immiscible thermoplastic. The large scale morphology was studied by performing interference contrast optical microscopy on samples etched with permanganate. A good correlation was obtained between the amount of thermoplastic in the immiscible regions and the overall fraction of thermoplastic in the sample.Etched samples were subject to ESC via bend tests in methanol and the effects of the morphology on the crack behaviour were observed microscopically while samples were still in the bent condition. It was evident that the large scale morphology was responsible for deflecting microcracks so that they preferentially grew along the interface between the immiscible thermoplastic and well mixed regions.
Chemistry and Properties of Poly(Arylene Ether Benzimidazole)S
Authors: Hergenrother Paul M. , Connell John W. , Smith Joseph G. 
Published: March 2011

AbstractAs part of a program to develop high performance structural resins for aerospace applications, a variety of poly(arylene ether benzimidazole)s were prepared by the nucleophilic displacement reaction of activated aromatic difluorides with bis(hydroxyphenylbenzimidazole) monomers. Glass transition temperatures as high as 364°C and room temperature unoriented thin film tensile strength and modulus as high as 22.8 ksi and 652 ksi, respectively, were observed. The polymer prepared from the reaction of 1,3-bis(4-fluorobenzoyl)benzene and 5,5′-bis[2-(4-hydroxyphenyl)benzimidazole] was selected for more extensive evaluation. To improve the processability, the molecular weight was reduced by upsetting the stoichiometry. Polymers were endcapped with benzimidazole, ethynyl and phenylethynyl groups. The chemistry, physical, and mechanical properties of these materials are presented.
Intelligent Automated Cure Processing of Polyimides
Authors: Kranbuehl David E. , Hart Sean M. , Loos Al 
Published: March 2011

AbstractAn intelligent, closed-loop expert system has been developed for the widely used high performance polyimide PMR-15. This expert system has been used for intelligent, automated sensor/model control of the fabrication of flat panels in both the autoclave and the thermal press. Panels have been made, ranging in thickness from less than 1/8 inch to 1/4 inch, using PMR-15 prepreg. Various prepreg samples have been used, ranging in age from fresh to one year old under freezer storage conditions. These materials exhibit significantly different processing properties as a result of the aging process. This expert system uses in-situ Frequency Dependent Electromagnetic Sensing (FDEMS), the Loos processing model for PMR-15, and the Qualitative Processing Automation Language (QPAL) software shell developed by Frances Abrams in conjunction with the Universal Technology Corporation for the United States Air Force.
Diamond Membranes For X-Ray Lithography Masks
Authors: Phillips William , Moreno Miguel A. 
Published: March 2011

AbstractProcess techniques have been developed to produce diamond membranes for application as x-ray lithography masks. Residual stress and grain size of the films are influenced by substrate temperature, chamber pressure, and methane concentration, and optimization of these parameters narrows the range of acceptable process conditions. A reactor geometry was chosen which has the capability to produce membranes with thickness uniformity of ± 7 percent across a 50 mm diameter. A cyclic renucleation technique was developed to maintain the grain size at low levels independent of film thickness. Membranes with RMS roughness of about 25 nm, as determined by atomic force microscopy, are fabricated reproducibly. The elastic modulus of small grained membranes deviates from that of larger grained membranes. This deviation must be taken into account in membrane distortion modeling calculations.
Development Of Robust Multilayer Optics For Use In High-Peak Power Radiation Environments
Authors: Macgowan Brian J. , Mrowka S. , Barbee T. W. , SILVA L. B. DA , EDER D.C. , Koch J.A. , Turner J.A. , Underwood J. H. 
Published: March 2011

AbstractIn many applications, x-ray mulhilayer mirrors are exposed to high peak fluxes of x-rays with subsequent damage to the mirror. Mirror damage is a particularly severe problem with the use of multilayers as cavity optics for short wavelength x-ray lasers. Intense optical and x-ray radiation, from the x-ray laser plasma amplifier, often damages the multilayer mirror on time scales of hundreds of picoseconds. The phenomenon of multilayer mirror damage by pulsed xray emission has been studied using short duration (500 psec) bursts of soft x-rays from a laser produced gold plasma. The results of the experiments will be compared with some simple models and the possibility of increasing the damage thresholds of short wavelength multilayer mirrors will be discussed.
Intra-Granular Microstructure And Stress In Sputtered Tungsten Thin Films
Authors: Ravet M.F. , Badawi K.F. , Durand N. , Lafontaine H. , Barnole V. , Haghiri-Gosnet A.M. 
Published: March 2011

AbstractIntra-granular microstructure and stress of tungsten rf magnetron sputtered thin films have been correlated for deposits with stresses ranging from 1000 MPa to −1000 MPa and belonging to the zone T of the Thornton's microstructural diagram. For pure α-W films, the stress values determined from the substrate deflection method were shown to be comparable with those determined by the x-ray diffraction sin2ψ method using the α-W (321) reflection. The lattice parameter a0of the unstressed material as deduced and was found to depend on the deposition conditions. In addition, a significant broadening of the (321) diffraction peak was observed foi compressive films, which suggests that the intra-granular microstructure has been changed. These original results are interpreted in terms of structural defects: in particular, compressive stress can be related to an interstitial feature.