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Radiolysis studies on reactive intermediates

Description: A more quantitative characterization of the structure and reaction mechanism of solvated electrons produced by high energy chemistry was developed. Neutral atoms may undergo solvation in polar media to cause significant geometrical rearrangement. The geometrical arrangement of six OH bond oriented water molecules around a localized electron is the preferred geometry in frozen aqueous systems even at low solute ion concentration. The energy level structure of electrons in polar aqueous and alcoh… more
Date: November 1, 1977
Creator: Kevan, L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Proceedings of the Eighth DOE Solar Photochemistry Research Conference Held at Interlaken Conference Center, Lake Geneva, Wisconsin, June 11-14, 1984

Description: These annual meetings bring together contractors of the Division of Chemical Sciences in its basic research program on solar photochemical energy conversion to exchange information and to give interested government officials an opportunity to assess the current status of the program. This year's meeting was joined by 12 Canadian scientists with similar interests in solar photochemistry. This volume contains the program of the meeting, a list of attendees, the abstracts of 29 formal presentation… more
Date: November 1984
Creator: Argonne National Laboratory
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Molecular ion photofragment spectroscopy

Description: A new molecular ion photofragment spectrometer is described which features a supersonic molecular beam ion source and a radio frequency octapole ion trap interaction region. This unique combination allows several techniques to be applied to the problem of detecting a photon absorption event of a molecular ion. In particular, it may be possible to obtain low resolution survey spectra of exotic molecular ions by using a direct vibrational predissociation process, or by using other more indirect d… more
Date: November 1, 1983
Creator: Bustamente, S.W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Photoelectron and photodissociation studies of free atoms and molecules, using synchrotron radiation

Description: High resolution synchrotron radiation and Zero-Kinetic-Energy Photoelectron spectroscopy were used to study two-electron transitions in atomic systems at their ionization thresholds. Using this same technique the core-ionized mainline and satellite states of N{sub 2} and CO were studied with vibrational resolution. Vibrationally resolved synchrotron radiation was used to study the dissociation of N{sub 2}, C{sub 2}H{sub 4}, and CH{sub 3}Cl near the N 1s and C 1s thresholds. The photoelectron sa… more
Date: November 1, 1991
Creator: Medhurst, L.J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Unimolecular and bimolecular reactions induced by state-specific vibrational excitation

Description: Toward the goal of understanding the role of vibrational energy in chemical reactions related to energy production, we have made several advances. They include the understanding of chemical properties of highly vibrationally excited molecules, the characterization of vibrationally excited radicals, and the development of experimental techniques to extend our ability to investigate transient and reactive chemical species. 11 refs., 1 fig.
Date: November 1, 1991
Creator: Dai, Hai-Lung.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Biological solar cells

Description: Recent reports have demonstrated the possibility of employing photoactive, biological membrane components in photoelectrochemical cells. Such systems have produced small photovoltages and photocurrents. Present studies in our laboratories have led to the attachment of a much simpler biological complex, the bacterial photosynthetic reaction center isolated from Rhodopseudomonas sphaeroides, directly onto an SnO/sub 2/ electrode. The light-induced primary charge separation processes which occur a… more
Date: November 1, 1979
Creator: Seibert, M. & Janzen, A. F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Energy transfer processes in solar energy conversion

Description: We have made substantial progress in experimental and theoretical studies in two areas: Photoinduced donor to acceptor electron transfer followed by back transfer in random solutions; and electronic excitation transport in systems with complex inhomogeneous spatial geometries and inhomogeneous energy distributions. Through the development of accurate statistical mechanical theories, we have been able to relate dynamics in complex systems to experimental observables. We have then used the experi… more
Date: November 1, 1989
Creator: Fayer, M.D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Pulsed laser kinetic studies of liquids under high pressure

Description: A high pressure apparatus has been constructed for measuring rates of reactions in liquids under pressures ranging from 1 atm to 2000 atm. This apparatus is being used to test the effect of ligand bulk on the rate of a thermal ring closure reaction. Microphonic photoacoustic signals obtained by illuminating solid samples with synchrotron soft x-rays and with visible laser beams have been successfully correlated with a theory for photoacoustic signal enhancement by volatile liquids. The concentr… more
Date: November 29, 1990
Creator: Eyring, E.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Photoexcited Charge Pair Escape and Recombination

Description: We report photocurrent transients arising from the pulsed laser excitation of the dipolar first excited singlet sate S{sub 1} of trans 4-dimethyl-amino-4{prime}-nitrostilbene (DMANS) in toluene solution. The currents arise from rotational reorientation of DMANS dipoles with respect to the axis of an applied electric field. The method appears to offer a simple and general approach to the measurement of the change in dipole moment upon electronic excitation of a molecule. In another experiment, d… more
Date: November 15, 1991
Creator: Braun, Charles L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Dynamics of Charge-Transfer Excited States Relevant to Photochemical Energy Conversion

Description: The primary objective of the research program is to gain a fundamental understanding of the factors governing the efficiency of excited-state charge transfer CT interactions between two chromophores that are brought together in close proximity, either by a very short covalent linkage or by ground-state complex formation. CT and van der Walls (vdW), interactions in covalently bonded bichromophoric compounds in condensed phase, as well as those in vdW complexes in supersonic jets, are being inves… more
Date: November 1, 1991
Creator: Lim, E. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Photoion-photoelectron coincidence studies clusters and transient molecules

Description: Experimental photoion-photoelectron coincidence (PIPECO) spectra have been obtained at different nozzle stagnation pressures for Ar, Kr, Xe, and CO dimers and trimers in the wavelength regions corresponding to the respective ground states through all states accessible with a photon energy of 20 eV. Ionization energies for all ground states were measured and agree well with previously reported values. The formation of stable dimer ions from fragmentation of larger cluster ions initially produced… more
Date: November 16, 1990
Creator: Norwood, K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Studies in chemical dynamics

Description: Progress made in the following studies is reported: low-energy electron scattering; variable-angle photoelectron spectroscopy; laser photochemistry and spectroscopy; and collisions in crossed molecular beams.
Date: November 22, 1978
Creator: Kuppermann, A
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Magnetic resonance studies of photo-induced electron transfer reactions

Description: Fourier Transform Electron Paramagnetic Resonance (FT EPR) is useful in study of photochemical reactions: a microwave pulse rotates the electron spin magnetization vector from z (magnetic field) into xy plane ([pi]/2 pulse); the time evolution of magnetization in xy plane, the free induction decay (FID), is sampled. Fourier transform of FID gives the frequency domain EPR spectrum of the free radicals, and the method is ideal for time-resolved studies of free radicals produced by pulsed-laser ex… more
Date: November 1, 1992
Creator: van Willigen, H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Reconstitution of halorhodopsin

Description: Halobacterium halobium contains a family of retinal-bound proteins: bacteriorhodopsin (bR) which mediates phototrophic growth as a light-riven proton pump, halorhodopsin (hR) which is a light-driven chloride pump, and one or more sensory rhodopsins (sR) which mediate a phototactic response. Two-dimensional crystallization of halorhodopsin has been attempted though the reconstitution of purified halorhodopsin with purple membrane lipid for electron microscopy work. The first important step for c… more
Date: November 1, 1989
Creator: Kong, T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Photoexcited charge pair escape and recombination. Progress report, November 15, 1990--November 14, 1991

Description: We report photocurrent transients arising from the pulsed laser excitation of the dipolar first excited singlet sate S{sub 1} of trans 4-dimethyl-amino-4{prime}-nitrostilbene (DMANS) in toluene solution. The currents arise from rotational reorientation of DMANS dipoles with respect to the axis of an applied electric field. The method appears to offer a simple and general approach to the measurement of the change in dipole moment upon electronic excitation of a molecule. In another experiment, d… more
Date: November 15, 1991
Creator: Braun, C. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Unimolecular and bimolecular reactions induced by state-specific vibrational excitation. Progress report

Description: Toward the goal of understanding the role of vibrational energy in chemical reactions related to energy production, we have made several advances. They include the understanding of chemical properties of highly vibrationally excited molecules, the characterization of vibrationally excited radicals, and the development of experimental techniques to extend our ability to investigate transient and reactive chemical species. 11 refs., 1 fig.
Date: November 1, 1991
Creator: Dai, Hai-Lung
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Radiation and Photochemistry Section annual report, October 1991--September 1992

Description: A survey is presented of research on reactive intermediates in the condensed phase and chemistry induced by energetic radiation. The survey is presented in two major parts: (1) ions, excited states, and other transients in condensed phase; and (2) role of solvents in chemical reactivity. Accelerator activities (20-MeV linac, 3-MeV Van de Graaff) are summarized.
Date: November 1, 1992
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Early events following radiolytic and photogeneration of radical cations in hydrocarbons

Description: Real-time studies in hydrocarbons have revealed a richness of chemistry involving the initial ionic species produced in radiolysis and photoionization. A modified radical cation mechanism patterned after the core mechanism for alkane radiolysis-formation of radical cations and their disappearance via ion-molecule reactions - is capable of explaining a wide range of observations in high-energy photochemistry, and thus unifies two high-energy regimes. Fundamental studies of radical cations sugges… more
Date: November 1, 1992
Creator: Werst, D. W. & Trifunac, A. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Dynamics of Charge-Transfer Excited States Relevant to Photochemical Energy Conversion. Progress Report, June 1, 1991--November 15, 1991

Description: The primary objective of the research program is to gain a fundamental understanding of the factors governing the efficiency of excited-state charge transfer CT interactions between two chromophores that are brought together in close proximity, either by a very short covalent linkage or by ground-state complex formation. CT and van der Walls (vdW), interactions in covalently bonded bichromophoric compounds in condensed phase, as well as those in vdW complexes in supersonic jets, are being inves… more
Date: November 1, 1991
Creator: Lim, E. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Laser flash photolysis, EPR and raman studies of liquids at elevated pressures. Progress report, April 1, 1993--November 19, 1993

Description: A laser flash photolysis kinetic study of a W(CO){sub 5} intermediate reacting with several different substituted 2,2{prime}-bipyridine ligands at pressures up to 150 MPa in liquid toluene has confirmed the considerable influence of steric hindrance on the mechanism of a thermal ring closure reaction. A similar laser flash photolysis kinetic study has been carried out with Mo(CO){sub 6} and several bidentate ligands resembling 2,2{prime}-bipyridine dissolved in supercritical carbon dioxide. A m… more
Date: November 19, 1993
Creator: Eyring, E. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Femtosecond dynamics of fundamental reaction processes in liquids: Proton transfer, geminate recombination, isomerization and vibrational relaxation

Description: The fast excited state intramolecular proton transfer of 3-hydroxyflavone is measured and effects of external hydrogen-bonding interactions on the proton transfer are studied. The proton transfer takes place in {approximately}240 fsec in nonpolar environments, but becomes faster than instrumental resolution of 110 fsec in methanol solution. The dynamics following photodissociation of CH{sub 2}I{sub 2} and other small molecules provide the first direct observations of geminate recombination. The… more
Date: November 1, 1992
Creator: Schwartz, B. J.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Magnetic resonance studies of photo-induced electron transfer reactions. Final report, June 1, 1990--May 31, 1993

Description: Fourier Transform Electron Paramagnetic Resonance (FT EPR) is useful in study of photochemical reactions: a microwave pulse rotates the electron spin magnetization vector from z (magnetic field) into xy plane ({pi}/2 pulse); the time evolution of magnetization in xy plane, the free induction decay (FID), is sampled. Fourier transform of FID gives the frequency domain EPR spectrum of the free radicals, and the method is ideal for time-resolved studies of free radicals produced by pulsed-laser ex… more
Date: November 1, 1992
Creator: van Willigen, H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Radiation and Photochemistry Section annual report, October 1991--September 1992

Description: A survey is presented of research on reactive intermediates in the condensed phase and chemistry induced by energetic radiation. The survey is presented in two major parts: (1) ions, excited states, and other transients in condensed phase; and (2) role of solvents in chemical reactivity. Accelerator activities (20-MeV linac, 3-MeV Van de Graaff) are summarized.
Date: November 1, 1992
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Luminescence process, refractory stabilities, and new and novel electronic states: scanning chemical reactions and novel products for laser induced isotope separation. Progress report, December 1, 1975--November 20, 1976

Description: Oven systems for high temperature metal vaporization at temperatures in excess of 2000/sup 0/C are being developed. Modifications of an apparatus appropriate to the production and study of small metal aggregates M/sub n/ (2 less than or equal to n less than or equal to 6) are discussed, including the construction and operation of argon ion and nitrogen pumped dye laser systems. The dye laser system is being used to induce fluorescence from small metal aggregates. Components necessary for interf… more
Date: November 1, 1976
Creator: Gole, J. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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