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Workshop on the interface between radiation chemistry and radiation physics

Description: Twenty-four papers are grouped under the session headings: measurements of physical and chemical properties, track structure modeling, spurs and track structure, and the 10/sup -16/ to 10/sup -12/ second region. Separate abstracts were prepared for 12 of the papers; four of the remaining papers had previously been abstracted. (DLC)
Date: March 1, 1983
Partner: UNT Libraries Government Documents Department

Iron hexacyanide/cytochrome-C - intramolecular electron transfer and binding constants - (pulse radiolytic study). Progress report for the period December 1, 1979-November 30, 1980

Description: Internal oxidation and reduction rates of horse cytochrome-c in the complexes, CII.Fe/sup III/(CN)/sup -3//sub 6/ and CIII.Fe/sup II/(CN)/sup -4//sub 6/, are 4.6.10/sup 4/s/sup -1/ and 3.3.10/sup 2/s/sup -1/, respectively. The binding sites of the iron hexacyanide ions on either CII or CIII are kinetically almost indistinguishable; binding constants range from 0.87.10/sup 3/ to 2.10/sup 3/M/sup -1/. The present pulse radiolytic kinetic data are compared with that from N.M.R, T-jump and equilibrium dialysis studies.
Date: December 1, 1980
Creator: Ilan, Y. & Shafferman, A.
Partner: UNT Libraries Government Documents Department

Nature of oxygen containing radicals in radiation chemistry and photochemistry of aqueous solutions. Annual progress report, September 1979-July 1980

Description: During this year, emphasis will be given on the properties of HO/sub 2/ and O/sub 2//sup -/ and OH, mainly in their role in biological systems. We will continue to study and elucidate how O/sub 2//sup -/ reacts in biological systems. The toxicity of O/sub 2//sup -/ is quite well established but the mechanism is still obscure. One way O/sub 2//sup -/ is toxic is that OH is formed from O/sub 2//sup -/ through reduction of Fe/sup 3 +/, and subsequently the reaction of Fe/sup 2 +/ with H/sub 2/O/sub 2/ (Fenton reaction). This mechanism is sometimes called the Haber Weiss Reaction. We will study if reduction of Fe/sup 3 +/ complexes by O/sub 2//sup -/ in biological systems does catalyze the Haber Weiss reaction and if OH is formed in this mechanism. The role of oxygen, radiosensitizers in radiation damage of bacteriophages and cells will be further studied, as well as on E. coli and enzymes. Use of different mutants, such as ones with repair deficiencies, or others which are deficient in glutathione will help to elucidate the role of O/sub 2//sup -/ and O/sub 2/ toxicity. We will try to elucidate the formation and role of OH, O/sub 2//sup -/ and O/sub 2/ in these systems as well as the relative contribution of endogenous and exogenous damage, and the role of direct and indirect radiation damage to cells. As there is some doubt how and if SOD protects cells from irradiation as literature results show lots of conflict, we will try to clear this point, in studies with E. coli mutants, and adding SOD endogenously and exogenously. We also intend to study if SOD (super oxide dismutase) does react only with O/sub 2//sup -/ or also with biological peroxides (RO/sub 2/) and hydroperoxides (RO/sub 2/H). Further studies of ...
Date: January 1, 1980
Creator: Czapski, G.
Partner: UNT Libraries Government Documents Department

Radiation Laboratory quarterly report, January 1, 1978--March 31, 1978. NDRL--1877

Description: Progress in various studies is reported including studies on: vapor phase structures of inorganic salts; solvated electrons; exchange perturbation theory for many-electron interactions; concept of orbital following; calculation of vibrational form factors in electron impact excitation; limiting behavior of molecule-molecule inelastic collision amplitude at zero momentum transfer; partially diffusion-controlled reactions of isolated pair in condensed media; field-dependent mobilities, T-R energy transfer between electronically excited argon and ground-state CO/sub 2/; dose and dose-rate effects in the radiolysis of liquids; coulombically correlated charge-pair distribution and recombination--the role of non-Gaussian diffusion; non-bonded interactions; pulse radiolysis studies of hydrocarbon radical scavenging processes; oxidation of methoxyhydroxycyclohexadienyl radicals by quinones; reaction of hydroxyl radical with phenol; solvent effects on the lifetimes of photogenerated biradicals; oxidation of amines by triplet duroquinone; production of singlet oxygen from excited states of aliphatic ketones; and measurement of electron spin-lattice relaxation times. (LK)
Date: April 12, 1978
Partner: UNT Libraries Government Documents Department

Effects of energy, distance and orientation on electron transfer rates studied by pulse radiolysis in organic media

Description: In the past few years the methods of radiation chemistry in organic media have made an enormous change in how we view electron transfer processes, as these media have proved the most useful for studying long distance electron transfer between molecules. This paper briefly summarizes a few of the aspects of this area and discusses some of the attributes and limitations of radiation tehniques, particularly pulse radiolysis, in organic solvents. 14 refs., 2 figs.
Date: January 1, 1987
Creator: Miller, J.R.
Partner: UNT Libraries Government Documents Department

Rates, distances, and energy control of electron tunneling reactions in rigid media

Description: Electron tunneling leads to transfer of trapped positive, or negative charge tens of angstroms in rigid matrices. Franck-Condon effects give energy specificity to charge transfer and ion recombination, and adds sensitivity to molecular structure, solvation and H/D isotope effects. The specificity is important in photosynthesis and solar energy storage as well as in radiation chemistry. We feel that the question of hopping vs. tunneling is definitely settled in favor of tunneling for intermolecular electron transfer at low temperatures. Hopping cannot yet be conclusively ruled out in reactions of trapped electrons. Hopping is expected to become important in many media near room temperature (T approx. less than 200/sup 0/K).
Date: January 1, 1979
Creator: Miller, John R. & Beitz, James V.
Partner: UNT Libraries Government Documents Department

Radiation chemistry of amino acids, peptides and proteins in relation to the radiation sterilization of high-protein foods. [106 references]

Description: An important source of information on the question of whether or not toxic or other deleterious substances are formed in the radiation sterilization of foods is the chemical study of reaction products and reaction mechanisms in the radiolysis of individual food components. The present evaluation of the radiation chemistry of amino acids, peptides and proteins outlines the various radiation-induced processes which lead to amino acid degradation and to the synthesis of amino acid derivatives of higher molecular weight. Among the latter are the ..cap alpha..,..cap alpha..'-diamino dicarboxylic acids which are formed as major products in the radiolysis of peptides both in aqueous solution and in the solid state. The ..cap alpha..,..cap alpha..'-diamino acids are of particular interest as irradiation products because they represent a class of compounds not normally encountered in plant and animal protein sources. Such compounds have, however, been isolated from certain types of bacteria and pathogenic toxins. All of the available data strongly suggest that the ..cap alpha..,..cap alpha..'-diamino acids are produced in significant yield in the radiation sterilization of high protein foods. The importance of initiating extensive chemical and biological studies of initiating extensive chemical and biological studies of these and of other high molecular weight products in irradiated food is emphasized.
Date: March 1, 1979
Creator: Garrison, W.M.
Partner: UNT Libraries Government Documents Department

Photochemistry and radiation chemistry of volatile silanes and germanes. Progress report, September 1, 1978-August 31, 1979

Description: The following are reported: reactions of methyl cations with ethylsilanes; reactions of ethyl, propyl, and butyl cations with methyl and ethylsilanes; the 147-nanometer photolysis of disilane; lifetimes and collisional stabilization of chemically activated ethylsilyl cations; formation of GeH/sub 5//sup +/ and the proton affinity of GeH/sub 4/; and multiphoton infrared decomposition of silanes.
Date: January 1, 1979
Creator: Lampe, F.W.
Partner: UNT Libraries Government Documents Department

Nature of oxygen containing radicals in radiation chemistry and photochemistry of aqueous solutions. Annual progress report, September 1978--July 1979

Description: The proposed research is a continuation of the work conducted under this contract and is outlined. During this year, the main emphasis will be given to study further the properties of HO/sub 2/ and O/sub 2//sup -/ and OH, mainly in their role in biological systems. We will continue to study and elucidate how O/sub 2//sup -/ reacts in biological systems. The toxicity of O/sub 2//sup -/ is quite well established, but the mechanism is still obscure. The Haber Weiss reaction most probably can not account for the toxicity of O/sub 2//sup -/ nor for the formation of singlet oxygen, nor of OH. We will study if reduction of Fe/sup 3 +/ complexes by O/sub 2//sup -/ in biological systems does catalyze the Haber Weiss reaction and if OH is formed in this mechanism. The role of oxygen, radiosensitizers in radiation damage of bacteriophages and cells will be further studied, as well as on E. Coli and Enzymes. We will try to elucidate the formation and role of OH, O/sub 2//sup -/ and O/sub 2/ in these systems as well as the relative contribution of endogenous and exogenous damage, and the role of direct and indirect radiation damage to cells. We intend also to study if SOD (super oxide dismutase) does react only with O/sub 2//sup -/ or also with biological peroxides (RO/sub 2/) and Hydroperoxides (RO/sub 2/H). Further studies of O/sub 2//sup -/ and O/sub 2/ with various cytochromes, and hemoglobins is planned.
Date: January 1, 1979
Creator: Czapski, G
Partner: UNT Libraries Government Documents Department

Detection of N-acetylglycine, N-acetylglycylglycine, and N-acetylglycylglycylglycine by paper chromatography

Description: This paper reports that the developing solvent of Kirchenmayer and Kuffner, n-butanol-acetic acid-water (8:1:10, v/v) can be used to separate and detect N-acetylglycine, N-acetylglycylglycine, and N-acetylglycylglycylglycine. The chromatographic procedure is described. After heating at 100/sup 0/C, the spots could be seen under uv light; acetone-bromocresol green-morpholine can also be used to make the spots show up. The R/sub f/ values are 0.59, 0.43, and 0.33, respectively. This procedure was used to detect these compounds in aqueous solutions of diglycine, triglycine, and tetraglycine, which were used as gamma-radiolysis targets. (DLC)
Date: June 1, 1978
Creator: Sokol, H.A.
Partner: UNT Libraries Government Documents Department

Picosecond pulse radiolysis studies to understand the primary processes in radiolysis

Description: The use of pulse radiolysis to learn about processes which occur before the beginning of chemical times is discussed. Two examples, the distance distribution of positive and negative ions in hydrocarbons, and the state of the dry electron are discussed in detail.
Date: January 1, 1984
Creator: Jonah, C.D. & Lewis, M.A.
Partner: UNT Libraries Government Documents Department

NMR spectra of transient radicals

Description: A time-resolved method for the study of structure and spin dynamics of transient radicals in liquids is described. Pulsed electron beam or pulsed laser irradiation is used to create transient radicals in solution. Irradiation is carried out in the field of a variable electromagnet, and the diamagnetic products are transferred rapidly using a fast flow system to an NMR probe. During the radical reaction, a 0.5 to 10 ..mu..s rf pulse is applied to the reacting sample at an appropriate frequency, corresponding to a nuclear energy level spacing of the given radical. Nuclear spin level population changes in the radical are transferred to its reaction product and detected as intensity changes in their NMR spectra. The method is illustrated using radiolyzed sodium malonate.
Date: January 1, 1984
Creator: Trifunac, A.D.; Chiu, T.M. & Nuttall, R.H.D.
Partner: UNT Libraries Government Documents Department

Characteristics of thermoluminescence glow curves for materials exhibiting more than one glow peak

Description: The properties of thermoluminescence glow curves, containing one or more glow peaks, have been determined for situations where the assumptions invoked to obtain the usual first and second order kinetics do not apply. First order kinetics occurs only when retrapping is negligible. If more than one glow peak is present and retrapping occurs between different types of traps the glow peaks can be approximated, except in the wings, by the usual first and second order expressions; but often physically unrealistic parameters are obtained. These studies indicate that dating is best accomplished with minerals exhibiting first order kinetics. 6 figures, 1 table.
Date: January 1, 1982
Creator: Levy, P.W.
Partner: UNT Libraries Government Documents Department

Contribution of electronically excited states to the radiation chemistry of organic systems. Progress report, September 1, 1978-August 31, 1979

Description: The effect of n-perfluorohexane to quench both the emission and photoionization current of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) in isooctane and in tetramethylsilane has been shown to be consistent with an interaction of perfluorohexane with some relatively long-lived, coherently excited state of TMPD that is generated at the photoionization threshold and which decays either to the emitting state of TMPD or to a geminate ion-pair. The 0/sup 0/ and 90/sup 0/ electron impact spectra of the stable isomers of C/sub 3/, C/sub 4/, and C/sub 5/ saturated hydrocarbons are being determined. Preliminary results show large structural effects on the lowest Rydberg singlet-triplet splittings. Two photon excited emission spectra of decalin, bicyclohexyl, and cyclohexane have been observed in good agreement with previously reported one-photon spectra. A weak emission from propylene has also been detected. From measurement of the photosensitized singlet emission of p-xylene by bicyclohexyl excited at 1740 A, it appears that the bicyclohexyl triplet contributes importantly to the sensitization. Also previously reported deviations from Stern-Volmer behavior in the fast-electron-excited process are found too in the photo-excited process (at 1740 A) and therefore cannot be attributed exclusively to ionic processes. The much larger ratio of excimer to monomer intensity in polystyrene as compared to neat liquid benzene appears to be due mainly to a reduced entropy of dissociation of the excimer when the phenyls are tied to the polymer backbone. Excimers formed therefore from distant phenyl groups may manifest themselves at high quencher concentrations and thus provide a new technique for probing polymer conformation.
Date: January 1, 1979
Creator: Lipsky, S.
Partner: UNT Libraries Government Documents Department

Studies of radiation-produced radicals and radical ions

Description: The radiolytic oxidation of anti-5-methylbicyclo(2.1.0)pentane gives the 1-methylcyclopentene radical cation as the sole rearrangement product H migration whereas oxidation of its syn isomer results in the highly selective formation of the 3-methylcyclopentene radical cation by methyl group migration. Since exactly the same stereoselectivity of olefin formation was observed in corresponding PET (photosensitized electron transfer) studies in the liquid phase, it is concluded that the rearrangement in this case also occurs through the intermediacy of radical cations. Clearly, the radical cation rearrangement must occur very rapidly (10{sup {minus}8}--10{sup {minus}9}s) under liquid-phase conditions at room temperature to compete with back electron transfer, and therefore the hydrogen (or methyl) migration is a fast process under these conditions. An intramolecular cycloaddition reaction was demonstrated in the radical cation rearrangement of 4-vinylcyclohexene to bicyclo(3.2.1)oct-2-ene. ESR studies show that the radiolytic oxidation of quadricyclane in Freon matrices under conditions of high substrate dilution leads to the bicyclo(3.2.0)hepta-2,6-diene radical cation as well as the previously reported norbornadiene radical cation, the former species predominating at sufficiently low concentrations.
Date: January 1, 1991
Creator: Williams, T.F.
Partner: UNT Libraries Government Documents Department

Electron spin resonance studies of radiation effects. Final report, 1964-1979 (including annual progress reports for 1978 and 1979)

Description: The discovery of new free radicals, largely in irradiated single crystals of nonmetallic solids, and the determination of the molecular and electronic structures of these paramagnetic species by electron spin resonance (ESR) spectroscopy, have been carried out using a wide variety of organic and inorganic materials. The mechanisms of production of radicals in solids, their motions, and their reactions have been investigated and some applicable general principles deduced. Emphasis has been on aliphatic free radicals from irradiated carboxylic acids and amides and their halogen-substituted derivatives, organometallic radicals and substituted cyclic hydrocarbon radicals; inorganic radicals studied include V centers, hypervalent radicals and electron adducts. Extensive investigations of paramagnetic transition metal complexes, particularly cyanides and fluorides, have been made. In all cases quantum mechanical calculations have been employed as far as possible in interpreting the data. An improved method for analyzing experimental ESR spectra of single crystals has been developed and a number of crystal structures have been determined to supplement the ESR studies. Applications of nuclear quadrupole resonance spectroscopy to the study of structure and bonding in inorganic solids have been made and a method for using nuclear magnetic relaxation data for estimating quadrupole coupling constants in liquids has been developed.
Date: July 1, 1979
Creator: Rogers, M.T.
Partner: UNT Libraries Government Documents Department

Picosecond pulse-conductivity technique applied to study excess-electron reactions in hydrocarbon mixtures

Description: To measure electron reactions on a picosecond timescale the investigators developed a picosecond pulse-conductivity technique, which makes use of the electron fine-structure pulses of our LINAC (pulse width 25 vs FWHM) to produce excess electrons and now detects changes in sample conductance under optimum conditions with an instrumental response of 18 ps. This resolution is in agreement with a theoretical estimate. This technique has been successfully applied to study excess electron reactions in solvents covering a mobility range from 0.24 to 100 cm/sup 2/V/sup -1/s/sup -1/; extension to lower mobility liquids seem possible.
Date: January 1, 1983
Creator: Bakale, G. & Beck, G.
Partner: UNT Libraries Government Documents Department

Summaries of FY 1979 research in the chemical sciences

Description: The purpose of this report is to help those interested in research supported by the Department of Energy's Division of Chemical Sciences, which is one of six Divisions of the Office of Basic Energy Sciences in the Office of Energy Research. Chemists, physicists, chemical engineers and others who are considering the possibility of proposing research for support by this Division wll find the booklet useful for gauging the scope of the program in basic research, and the relationship of their interests to the overall program. These smmaries are intended to provide a rapid means for becoming acquainted with the Chemical Sciences program for members of the scientific and technological public, and interested persons in the Legislative and Executive Branches of the Government, in order to indicate the areas of research supported by the Division and energy technologies which may be advanced by use of basic knowledge discovered in this program. Scientific excellence is a major criterion applied in the selection of research supported by Chemical Sciences. Another important consideration is the identifying of chemical, physical and chemical engineering subdisciplines which are advancing in ways which produce new information related to energy, needed data, or new ideas.
Date: May 1, 1980
Partner: UNT Libraries Government Documents Department

Radiation effects

Description: For the meeting of the Commission on Radiochemistry and Nuclear Techniques our chairman has submitted comments on potential problems that the Commission should consider in Lyon which had been posed by various members. In one of these comments, Prof. Roth has mentioned the problem of radiation effects in solids and in water and water solutions. The radiolysis of water has been of concern for a large number of years, but as Prof. Roth notes, the radiation effects on the first wall of fusion reactors is a problem that has arisen only in recent years and for which no critical data compilation is presently available. This paper has been prepared in response to Prof. Roth's comments and indicates a possible area, which the Commission might conceivably address at this meeting and/or in the near future. 7 refs.
Date: January 1, 1985
Creator: Holden, N.E.
Partner: UNT Libraries Government Documents Department

(Ionization in liquids)

Description: This document describes charge transport following ionization of model liquids and how this process may be important in carcinogenesis. 15 refs., 2 figs., 4 tabs. (MHB)
Date: January 1, 1991
Partner: UNT Libraries Government Documents Department

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 alcoholic glasses was systematized from a comparison of photoconductivity and optical spectra. Experimental and theoretical evidence on electron solvation was evaluated to suggest the dominance of first solvation shell orientation in the solvation process. A laser photolysis study as a function of temperature suggests that electron solvation in ethanol glass occurs by a hindered molecular reorientation mechanism. In mixed polar and nonpolar glassy matrices it was shown that the electron is first solvated in the nonpolar matrix and is later transformed to a more stable species surrounded by the polar molecules. It was found that the spin lattice relaxation of solvated electrons is dominated by a new mechanism characteristic of disordered matrices which involves relaxation by tunneling modes in the matrix. The noninteracting spin packet model of electron spin resonance lines was shown to apply to solvated electrons in deuterated matrices but not in protiated matrices. A new type of recombination fluorescence experiment was devised which allows easy distinction between tunnelling and diffusive recombination mechanisms between solvate electrons and cations. Several theoretical studies have helped to delimit the applicability of an electron tunneling mechanism to solvated electron reactions. Electron spin echospectrometry was used to demonstrate that silver atoms undergo dramatic solvation and desolvation changes in frozen aqueous systems.
Date: November 1, 1977
Creator: Kevan, L.
Partner: UNT Libraries Government Documents Department