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in subjects: "Electron Transfer"

open access

Study of one-dimensional electron hopping and its effects on ESR line shape

Random hopping processes between discrete sites along a finite open chain or around a closed finite loop are examined. Closed form formulae are prescribed for the dependence of the ESR (electron spin resonance) line shape on the chain length and hopping rate. Significant differences between the closed loop and open chain are demonstrated. Deviation at short time from the results of diffusion in a continuum is presented.

Date: August 1, 1997

Creator: Tang, Jau; Dikshit, S. N. & Norris, J. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Photosynthetic hydrogen and oxygen production by green algae

An overview of photosynthetic hydrogen and oxygen production by green algae in the context of its potential as a renewable chemical feed stock and energy carrier is presented. Beginning with its discovery by Gaffron and Rubin in 1942, motivated by curiosity-driven laboratory research, studies were initiated in the early 1970s that focused on photosynthetic hydrogen production from an applied perspective. From a scientific and technical point of view, current research is focused on optimizing ne… more

Date: December 31, 1997

Creator: Greenbaum, E. & Lee, J.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Surface plasmon enhanced interfacial electron transfer and resonance Raman, surface-enhanced resonance Raman studies of cytochrome C mutants

Surface plasmon resonance was utilized to enhance the electron transfer at silver/solution interfaces. Photoelectrochemical reductions of nitrite, nitrate, and CO{sub 2} were studied on electrochemically roughened silver electrode surfaces. The dependence of the photocurrent on photon energy, applied potential and concentration of nitrite demonstrates that the photoelectrochemical reduction proceeds via photoemission process followed by the capture of hydrated electrons. The excitation of plasm… more

Date: November 8, 1999

Creator: Zheng, Junwei

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

Experience with Unstructured-Mesh Electron Transport with Massively Parallel Computing

No Description Available.

Date: July 17, 2000

Creator: Drumm, Clifton R.; Fan, Wesley C.; Lorence, Leonard & Powell, Jennifer L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Final Technical Brief / DOE grant DE-FG03-96 ER 62219. Computational Study of Electron Tunneling in Proteins

Electron transfer (ET) processes in proteins are characterized by the motion of a single electron between centers of localization (such as the chlorophyll dimer in photosynthetic reaction centers). An electronic donor state D is created by the injection of an electron or by photo-excitation, after which the system makes a radiationless transition to an acceptor state A., resulting in the effective transfer of an electron over several angstroms. The experimental and theoretical understanding of … more

Date: March 3, 1999

Creator: Regan, Jeffrey J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

New architectures for integrated photoelectrochemical systems. Final report, Sept. 1998 - Dec. 2001

During the three year grant period, significant progress has been made toward the accomplishment of each of the goals outlined in the original proposal. The budget proposed for the project was also expended fully, as originally projected. In accord with these objectives, we have prepared an array of new macromolecules and supramolecular aggregates in which a light-sensitive organic group initiates long range photoinduced electron transfer in this designed heterogeneous environment. In doing so,… more

Date: March 31, 2002

Creator: Fox, Marye Anne

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Design, Synthesis and Study of Dendrimers as Nanoscaffolds for Solar Energy Harvest

Designing molecules in which the vectorial motions of charges can be controlled has been of significant research interest in the recent past. Covalent linear arrays of chromophores or other molecular assemblies such as liquid crystals, zeolites, polymers, peptides, and amphiphiles have all been used as components for this purpose. Significant amount of this effort also involved the use of dendrimers as the molecular architecture. The structural feature in which multiple functionalities are pres… more

Date: January 25, 2008

Creator: Thayumanavan, Sankaran

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

EMSL Geochemistry, Biogeochemistry and Subsurface Science-Science Theme Advisory Panel Meeting

This report covers the topics of discussion and the recommendations of the panel members. On December 8 and 9, 2010, the Geochemistry, Biogeochemistry, and Subsurface Science (GBSS) Science Theme Advisory Panel (STAP) convened for a more in-depth exploration of the five Science Theme focus areas developed at a similar meeting held in 2009. The goal for the fiscal year (FY) 2011 meeting was to identify potential topical areas for science campaigns, necessary experimental development needs, and s… more

Date: August 1, 2011

Creator: Brown, Gordon E.; Chaka, Anne; Shuh, David K.; Roden, Eric E.; Werth, Charles J.; Hess, Nancy J. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

The Moment Condensed History Algorithm for Monte Carlo Electron Transport Simulations

We introduce a new Condensed History algorithm for the Monte Carlo simulation of electron transport. To obtain more accurate simulations, the new algorithm preserves the mean position and the variance in the mean position exactly for electrons that have traveled a given path length and are traveling in a given direction. This is accomplished by deriving the zeroth-, first-, and second-order spatial moments of the Spencer-Lewis equation and employing this information directly in the Condensed Hi… more

Date: February 27, 2001

Creator: Tolar, D R & Larsen, E W

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

On the neutralization of singly and multicharged projectiles during grazing interactions with LiF(100)

Measurements are reported of scattered neutral fractions for Na, K, Cs, and Ne singly and multicharged ions, and of scattered negative ion fractions for incident O, F, and B projectiles grazingly incident on LiF(100) as function of projectile velocity. In the case of the Na and Ne incident ions, significant dependence of the scattered neutral fractions on incident charge state is found, which is most pronounced at the lowest investigated velocities. Possible reasons for the observed initial cha… more

Date: October 1996

Creator: Meyer, F. W.; Yan, Q.; van Emmichoven, P. Z.; Spierings, G. & Hughes, I. G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Study of Intermediates From Transition Metal Excited-State Electron-Transfer Reactions. Final Report, August 4, 1986--August 31, 1997

The techniques of continuous photolysis and pulsed laser flash photolysis, continuous and pulse radiolysis, fast-scan cyclic voltammetry, and time-resolved fluorimetry have been used to examine intramolecular electron transfer within the solvent quenching cage, photodynamics of quenching of the excited states of transition-metal photosensitizers, the properties of excites states and one-electron reduced forms, ground- and excited-state interactions with solutes, and photoinduced oxidations of o… more

Date: December 31, 1997

Creator: Hoffman, M. Z.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Molecular structure determination for photogenerated intermediates in photoinduced electron transfer reactions using steady-state and transient XAFS

Many photoinduced electron transfer reactions are accompanied by nuclear rearrangements of the molecules involved. In order to understand the reactivities of the molecules and the reaction mechanisms, precise information on the molecular structural changes accompanying the electron transfer is often required. We present here conventional XAFS and transient energy dispersive XAFS studies on structures of excited and photoinduced charge separated state of porphyrin and porphyrin based supermolecu… more

Date: October 1, 1996

Creator: Chen, L.X.; Wasielewski, M.R. & Rajh, T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

ECR-based atomic collision physics research at ORNL

After a brief summary of the present capability and configuration of the ORNL Multicharged Ion Research Facility (MIRF), and of upcoming upgrades and expansions, the presently on-line atomic collisions experiments are described. In the process, the utility of intense, cw ion beams extracted from ECR ion sources for low-signal rate experiments is illustrated.

Date: April 1997

Creator: Meyer, F. W.; Bannister, M. E.; Hale, J. W. & Havener, C. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Third International Symposium: Cytochrome p450 Biodiversity. Final Report, January 1, 1995--December 31, 1995

The Symposium was held on October 8-12, 1995 at the Marine Biological Laboratory in Woods Hole Massachusetts. Other international symposia promote cytochrome P450 research but have a primary focus on mammalian systems. This symposium is exclusively devoted to research in other organisms, and major topics reflect the distribution and dominance of non-mammalian species in the biosphere. The five sessions focused on basic mechanism, regulation, biodiversity, host-parasite interactions, and practic… more

Date: March 1, 1997

Creator: Loper, J. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Electrochemistry in concentrated organic redox solutions. Unusual reaction mechanisms and transport phenomena

This report discusses and gives several examples of voltammetric studies in concentrated organic solutions and show that quantitative measurements can be performed under conditions where redox species is present in molar quantities. A brief description of experimental methods and theory of ultramicroelectrode techniques is presented. Examples of transport phenomena, coupled homogeneous reactions, and magnetic field effects in highly concentrated organic redox solutions are given.

Date: April 1, 1997

Creator: Ragsdale, S. R.; Paulson, S. C.; White, H. S. & Feldberg, S. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

PHOTOELECTROCHEMISTRY AND PHOTOCATALYSIS IN NANOSCALE INORGANIC CHEMICAL SYSTEMS

The goal of our DOE-supported research has been to explore the use of solid state materials as organizing media for, and as active components of, artificial photosynthetic systems. In this work we strive to understand how photoinduced electron and energy transfer reactions occur in the solid state, and to elucidate design principles for using nanoscale inorganic materials in photochemical energy conversion schemes. A unifying theme in this project has been to move beyond the study of simple tra… more

Date: May 27, 2007

Creator: Mallouk, Thomas E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

CHEMICAL TRAPPING OF A PRIMARY QUANTUM CONVERSION PRODUCT INPHOTOSYNTHESIS

The capacity of photosynthetic organisms to exhibit photo-induced electron paramagnetic resonance (EPR) signals has been known for over ten years. Subcellular units of photosynthetic materials, the quantasomes and the chromatophores, are capable of Hill Reaction activity, and also of exhibiting the light-induced EPR signals. This, coupled with the rapid rise and decay kinetics of these signals, suggests but does not prove that the unpaired electrons are involved in the initial electron transfer… more

Date: September 9, 1966

Creator: Corker, Gerald A.; Klein, Melvin P. & Calvin, Melvin.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

THE ROLE OF DIELECTRIC CONTINUUM MODELS IN ELECTRON TRANSFER: THEORETICAL AND COMPUTATIONAL ASPECTS.

Condensed phase physical and chemical processes generally involve interactions covering a wide range of distance scales, from short-range molecular interactions requiring orbital overlap to long-range coulombic interaction between local sites of excess charge (positive or negative monopoles). Intermediate-range distances pertain to higher-order multipolar as well as inductive and dispersion interactions. Efforts to model such condensed phase phenomena typically involve a multi-tiered strategy i… more

Date: November 1, 2006

Creator: NEWTON, M.D.

Item Type: Book

Partner: UNT Libraries Government Documents Department

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Mechanisms and Dynamics of Abiotic and Biotic Interactions at Environmental Interfaces

The Stanford EMSI (SEMSI) was established in 2004 through joint funding by the National Science Foundation and the OBER-ERSD. It encompasses a number of universities and national laboratories. The PNNL component of the SEMSI is funded by ERSD and is the focus of this report. This component has the objective of providing theory support to the SEMSI by bringing computational capabilities and expertise to bear on important electron transfer problems at mineral/water and mineral/microbe interfaces.… more

Date: June 1, 2006

Creator: Roso, Kevin M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Molecular Mechanism of Uranium Reduction by Clostridia and Its Manipulation.

This research addresses the need for detailed studies of the enzymatic mechanisms for reduction of radionuclides and/or metals by fermentative microorganisms. The overall objective of this research is to elucidate systematically the molecular mechanisms involved in the reduction of uranium by Clostridia. We propose to (1) determine the role of hydrogenases in uranium reduction, (2) purify the enzymes involved in uranium reduction, (3) determine the mechanisms of reduction, e.g., one or two elec… more

Date: November 16, 2006

Creator: Francis, A. J.; Gao, W.; Chidambaram, D. & Dodge, C. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Microbially Mediated Immobilization of Contaminants Through In Situ Biostimulation

In most natural environments, a multitude of metabolic substrates are resent simultaneously. Organisms that can utilize uranium as a metabolic substrate for respiration also may have the ability to use a variety of other oxidized substrates as electron acceptors. Thus, these substrates are, in effect, competing for electrons that are being passed through the electron transport chain during respiration. To assess the feasibility of in situ immobilization of uranium in subsurface environments and… more

Date: July 31, 2003

Creator: Fendorf, Scott

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Final report to the Department of Energy for Grant DE-FG02-01ER54663

Funds provided from the DOE award were used to support student participation in the 54th Gaseous Electronics Conference held at Penn State Unversity October 9-12, 2001. DOE funds were distributed to 27 graduate students, each of whom presented research results at the conference. DOE resources were supplemented by donations from several industrial firms.

Date: October 1, 2001

Creator: McGrath, Robert T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Formation of P{sup +}Q{sub B}{sup -} via B-branch electron transfer in mutant reaction centers.

The crystallographic observation of two symmetry-related branches of electron transfer cofactors in the structure of the bacterial reaction center (RC) 13 years ago [1] remains an enigma in light of experimental observations that show that only the A branch is active in the initial electron transfer steps in wild-type RCs. Unidirectional electron flow has been attributed to localized asymmetries between the A and B branches that lead to differences in: (1) the electronic couplings of the cofact… more

Date: August 14, 1998

Creator: Laible, P. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Nonlinear optical properties of porphyrin and chlorophyll dimers studied by degenerated four wave mixing

As one of the important elements in natural and artificial electron transfer and energy transfer processes, porphyrin and its derivatives have received much attention in photoelectronics and photoelectronic materials. As our first attempt to relate the {pi}-{pi} electronic couplings between porphyrin macrocycles to apparent third order nonlinear susceptibilities, we measured {chi}({sup 3}) for several porphyrin and chlorophyll a derivatives, including dimers with different configurations. Our p… more

Date: December 31, 1992

Creator: Chen, L. X. Q.

Item Type: Article

Partner: UNT Libraries Government Documents Department