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Search Publications by: Daniel A Fischer (Fed)

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Displaying 51 - 75 of 231

Soft X-ray Characterization Technique for Li Batteries under Operating Conditions

September 1, 2009
Author(s)
Daniel A. Fischer, Cole Petersburg, Robert Daniel, Cherno Jaye, Faisal Alamgir
O K edge and Co L edge near edge X-ray absorption fine structure (NEXAFS) was used to examine the cathode of an intact solid-state lithium ion battery. The novel technique allowed for the simultaneous acquisition of partial electron yield and fluorescence

Depressed Phase Transition in Solution-Grown VO2 Nanostructures

July 1, 2009
Author(s)
Daniel A. Fischer, Luisa Whittaker, Cherno Jaye, Zugen Fu, Sarbajit Banerjee
The first-order metal insulator phase transition in VO2 is characterized by an ultrafast several orders of magnitude change in electrical conductivity and optical transmittance, which makes this material an attractive candidate for the fabrication of

Substrate-dependent interface composition and charge transport in films for organic photovoltaics

June 9, 2009
Author(s)
David Germack, Calvin Chan, Behrang Hamadani, Lee J. Richter, Daniel A. Fischer, David J. Gundlach, Dean DeLongchamp
The buried interface composition of polymer-fullerene blends is found by near edge X ray absorption fine structure (NEXAFS) spectroscopy to depend on the surface energy of the substrate upon which they are cast. The interface composition determines the

Determination of the Electron Escape Depth for NEXAFS Spectroscopy

June 2, 2009
Author(s)
Daniel A. Fischer, K E. Sohn, M D. Dimitriou, Jan Genzer, C Hawker, E. J. Kramer
Depth profiling using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to determine the carbon atom density as a function of depth by analyzing the post-edge signal in NEXAFS spectra. We show that the common assumption in the

Modification of PET surfaces with self-assembled monolayers of organosilane precursors

May 13, 2009
Author(s)
Daniel A. Fischer, Ali Ozcam, Kirill Effimenko, Cherno Jaye, Richard Spontak, Jan Genzer
We report on a facile, robust and rapid method by which poly(ethylene terephthalate) (PET) surfaces can be chemically modified while avoiding chemical degradation. Specifically, we demonstrate that brief exposure of PET surfaces to ultraviolet/ozone (UVO)

Elastic and adhesive properties of alkanethiol self-assembled monolayers on gold

March 30, 2009
Author(s)
Frank W. DelRio, Cherno Jaye, Daniel A. Fischer, Robert F. Cook
Elastic and adhesive properties of alkanethiol (CH3(CH2)n 1SH) self-assembled monolayers on gold are investigated by atomic force microscopy and correlated with surface structure via near edge x-ray absorption fine structure spectroscopy. As the chain

Semiconducting Thienothiophene Copolymers: Design, Synthesis, Morphology and Performance in Thin Film Organic Transistors

March 1, 2009
Author(s)
Iain McCulloch, Martin Heeney, Michael L. Chabinyc, Dean DeLongchamp, Regis J. Kline, Michael Colle, Warren Duffy, Daniel A. Fischer, David J. Gundlach, Behrang Hamadani, Rick Hamilton, Lee J. Richter, Alberto Salleo, Martin Shkunov, David Sparrowe, Steve Tierney, Weimin Zhang
Organic semiconductors are emerging as a viable alternative to amorphous silicon in a range of thin film transistor devices. , With the possibility to formulate these p-type materials as inks and subsequently print into patterned devices, organic based

The molecular basis of mesophase ordering in a thiophene-based copolymer

February 18, 2009
Author(s)
Dean M. DeLongchamp, Regis J. Kline, Youngsuk Jung, Eric K. Lin, Daniel A. Fischer, David J. Gundlach, Andrew Moad, Lee J. Richter, Michael F. Toney, Martin Heeney, Iain McCulloch
The carrier mobility of poly(2,5-bis(3-alkylthiophen-2-yl) thieno[3,2-b]thiophene) semiconductors can be substantially enhanced after heating through a thermotropic mesophase transition, which causes a significant improvement in thin film structural order

Surface Engineering of Styrene/PEGylated-Fluoroalkyl Styrene Block Copolymer Thin Films

January 1, 2009
Author(s)
Elisa Martinelli, Sara Menghetti, Giancarlo Galli, Antonella Glisenti, Sitaraman Krishnan, Marvin Y. Paik, Christopher K. Ober, Detlet-M Smilgies, Daniel A. Fischer
A series of diblock copolymers prepared from styrenic monomers was synthesized using ATRP. One block was derived from styrene while the second block was prepared from a styrene modified with an amphiphilic PEGylated-fluoroalkyl side chain. The surface

Electronic Structure and Chemistry of Iron-Based Metal Oxide Nanostructured Materials: A NEXAFS Investigation of BiFeO3, Bi2Fe4O9, a-Fe2O3, g-Fe2O3, and Fe/Fe3O4

November 6, 2008
Author(s)
Tae-Jin Park, S Sambasivan, Daniel A. Fischer, R Ramesh, J A. Misewich, S S. Wong
We present a systematic and detailed Near Edge X-ray Absorption Fine Structure (NEXAFS) experimental investigation of the electronic structure and chemistry of iron-based metal oxide nanostructured (FeMONS) materials including BiFeO3, Bi2Fe4O9, a-Fe2O3, ?-

Characterization of Monolayer Formation on Aluminum-Doped Zinc Oxide Thin Films

August 21, 2008
Author(s)
C Rhodes, S E. Lappi, Daniel A. Fischer, S Sambasivan, Jan Genzer, S Franzen
The optical and electronic properties of aluminum-doped zinc oxide (AZO) thin films on a glass substrate have been investigated experimentally and theoretically. Optical studies with coupling in the Kretschmann configuration reveal an angle-dependent

Systematic oxidation of polystyrene by ultraviolet-ozone,characterized by near edge x-ray absorption fine structure and contact angle

August 5, 2008
Author(s)
Daniel A. Fischer, Robert Klein, Joseph~undefined~undefined~undefined~undefined~undefined Lenhart
The process of implanting oxygen in polystyrene (PS) via exposure to ultraviolet-ozone (UV-O) was systematically investigated using the characterization technique of near edge x-ray absorption fine structure (NEXAFS). Samples of PS exposed to UV-O for 10s

The Impact of the Dielectric / Semiconductor Interface on Microstructure and Charge Carrier Transport in High-Performance Polythiophene Transistors

May 14, 2008
Author(s)
Youngsuk Jung, Regis J. Kline, Eric K. Lin, Daniel A. Fischer, Michael F. Toney, Martin Heeney, Iain McCulloch, Dean DeLongchamp
The performance of organic field-effect transistors (OFETs) significantly depends on the properties of the interface between the semiconductor and gate dielectric. Here, we study the impact of chemically modified and morphologically controlled dielectrics

The Effect of Interfacial Roughness on the Thin Film Morphology and Charge Transport of High-Performance Polythiophenes

March 11, 2008
Author(s)
Y S. Jung, Regis J. Kline, Daniel A. Fischer, Eric K. Lin, Martin Heeney, Iain McCulloch, Dean DeLongchamp
We control and vary the roughness of a dielectric upon which a high-performance polymer semiconductor, poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (pBTTT) is cast, to determine the effects of roughness on thin-film microstructure and the