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(X-ray diffraction experiments with condenser matter)

Description: This report discusses research on the following topics: high-{Tc} superconductors; The response of crystal to an applied electric field; quasicrystals; surface structure and kinetics of surface layer formation; EXAFS studies of superconductors and heterostructures; effect of iron on the crystal structure of perovskite; x-ray detector development; and SAXS experiments. (LSP)
Date: January 1, 1990
Creator: Coppens, P.
Partner: UNT Libraries Government Documents Department

Determination of solvation kinetics in supercritical fluids

Description: Objective was to study solvation processes in pure and entrainer-modified supercritical fluids. Specific topics were: Kinetics for solvation in supercritical media, influence on entrainers on solvation, reversibility of solvation, effects of solvation on intramolecular solute-solute interaction kinetics, and impact of fluid density on these processes. Time-resolved fluorescence spectroscopy was used as the main analytical tool. A summary is given of the 2.5 years' research.
Date: January 1, 1993
Creator: Bright, F.V.
Partner: UNT Libraries Government Documents Department

Determination of solvation kinetics in supercritical fluids. Project summary, August 15, 1993--May 3, 1994

Description: This project is directed on determining effects of supercritical fluids on salvation and chemical reactions. Sub-projects are: understanding the effects of neat and entrainer-modified supercritical fluids on solute-fluid interactions; determining the influence of supercritical fluids on energetics and dynamics of solute conformation; and probing effects of continuous phase density on internal dynamics of reverse micelles formed in supercritical fluids. In order to follow these fast molecular-level processes, modern picosecond in-situ optical spectroscopy is being used. To date this work has: helped define how ``diffusion controlled`` reactions proceed in supercritical fluids; determined how and on what time scale entrainers preferentially solvate solutes in the near-critical region; shown that the conformation (i.e., reactivity) of flexible solutes can be altered easily with fluid density; shown how lateral diffusion within reverse micelles (formed in supercritical alkanes) is affected by the continuous phase density; and begun to probe how the conformation of polymers can be controlled with supercritical fluids. This is leading to a better molecular-level understanding of the chemistry of supercritical fluids.
Date: August 1, 1994
Creator: Bright, F. V.
Partner: UNT Libraries Government Documents Department

Determination of solvation kinetics in supercritical fluids. Summary report

Description: Objective was to study solvation processes in pure and entrainer-modified supercritical fluids. Specific topics were: Kinetics for solvation in supercritical media, influence on entrainers on solvation, reversibility of solvation, effects of solvation on intramolecular solute-solute interaction kinetics, and impact of fluid density on these processes. Time-resolved fluorescence spectroscopy was used as the main analytical tool. A summary is given of the 2.5 years` research.
Date: January 1, 1993
Creator: Bright, F. V.
Partner: UNT Libraries Government Documents Department

Group transfer and electron transfer reactions of organometallic complexes

Description: During 1994, despite the disruptions, the authors have made progress in several aspects of their research on electron transfer reactions between organometallic complexes. This summary covers three areas that are relatively complete: (1) reactions between metal carbonyl anions and metal carbonyl halides, (2) reactions of hydrido- and alkyl-containing anions (RFe(CO){sup {minus}}{sub 4} and RW (CO){sub 5}{sup {minus}}) with metal carbonyl cations and (3) reactions of a seventeen-electron complex (Cp{asterisk}Cr(CO){sub 3}{lg_bullet}) with metal carbonyl derivatives. Two areas of examination that have just begun (possible carbene transfer and the possible role of metal carbonyl anions in carbon-hydrogen bond activation) will also be described.
Date: December 1, 1994
Creator: Atwood, J. D.
Partner: UNT Libraries Government Documents Department

[Group transfer and electron transfer reactions of organometallic complexes]: Summary of research accomplished in 1993

Description: In the past year the research on mechanisms of electron transfer processes between organometallic complexes has continued to progress with emphasis on two electron processes and on reactions of organometallic radicals. This summary will highlight the research on: (1) halide transfer reactions, (2) alkyl and acyl transfer reactions and (3) reactions of seventeen-electron organometallic complexes. At this point some conclusions on the transfer of hydrogen, halogen and methyl as the cation, radical and anion can be made. For each group, transfer as the cation is more facile. For hydrogen, transfer as the hydride is considerably slower, but H{center_dot} transfers nearly as rapidly as H{sup +}. Methyl could be transferred as CH{sub 3}{sup +} or CH{sub 3}{sup {minus}}, but not as the radical. Halogens transfer readily as X{sup +}, more slowly as X{center_dot} and not at all as X{sup {minus}}.
Date: December 31, 1993
Partner: UNT Libraries Government Documents Department