The orientation of carbonyl in carbonmonoxy cytochrome oxidase and its transient photoproducts. Direct evidence from time-resolved infrared linear dichroism

1989 ◽  
Vol 111 (24) ◽  
pp. 8962-8963 ◽  
Author(s):  
R. Brian Dyer ◽  
Juan J. Lopez-Garriga ◽  
Olof Einarsdottir ◽  
William H. Woodruff
Keyword(s):  
Cytochrome Oxidase ◽  
Direct Evidence ◽  
Linear Dichroism ◽  
Time Resolved

Time-resolved infrared linear dichroism studies of the orientation of CO in carbonmonoxy cytochrome oxidase

1989 ◽  
Vol 36 (3-4) ◽  
pp. 267
Author(s):  
W.H. Woodruff ◽  
R.B. Dyer ◽  
J.J. López-Garriga ◽  
'O. Einarsdóttir ◽  
P.M. Killough
Keyword(s):  
Cytochrome Oxidase ◽  
Linear Dichroism ◽  
Time Resolved

Green rust as a precursor for magnetite: an in situ synchrotron based study

2008 ◽  
Vol 72 (1) ◽  
pp. 201-204 ◽  
Author(s):  
A. Sumoondur ◽  
S. Shaw ◽  
I. Ahmed ◽  
L. G. Benning
Keyword(s):  
Direct Evidence ◽  
Green Rust ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Subsequent Transformation ◽  
Rapid Formation ◽  
Reaction Proceeds

AbstractIn this study, direct evidence for the formation of magnetite via a green rust intermediate is reported. The Fe(II) induced transformation of ferrihydrite, was quantified in situ and under O2-free conditions using synchrotron-based time-resolved energy dispersive X-ray diffraction. At pH 9 and Fe(II)/Fe(III) ratios of 0.5 and 1, rapid growth (6 min) of sulphate green rust and its subsequent transformation to magnetite was observed. Electron microscopy confirmed these results, showing the initial rapid formation of hexagonal sulphate green rust particles, followed by the corrosion of the green rust as magnetite growth occurred, indicating that the reaction proceeds via a dissolution-reprecipitation mechanism. At pH 7 and Fe(II)/Fe(III) ratio of 0.5, sulphate green rust was the stable phase, with no transformation to magnetite.

Application of time-resolved linear dichroism spectroscopy: Intensity borrowing in charge transfer complex absorption spectra

2003 ◽  
Vol 81 (6) ◽  
pp. 567-574
Author(s):  
Dustin Levy ◽  
Bradley R Arnold
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Complex ◽  
Chlorinated Solvents ◽  
Linear Dichroism ◽  
Charge Transfer Transition ◽  
Time Resolved ◽  
Transition Energies ◽  
Charge Transfer Transitions ◽  
Donor Acceptor ◽  
Influence Of Solvent

Time-resolved linear dichroism spectroscopy has been used to study the influence of solvent on the charge transfer complex formed between hexamethylbenzene and 1,2,4,5-tetracyanobenzene. It was shown that cyano-substituted solvents induce a 1500 cm–1 increase in the charge transfer transition energies relative to those observed in chlorinated solvents. Furthermore, the angle between the charge transfer absorption transition moments and the photochemically produced radical anion absorption transition moment, after relaxation, has been measured for this complex in several solvents. A simple model was used to correlate the angles measured using time-resolved linear dichroism spectroscopy with the extent of localized excitation mixed into the charge transfer transitions. These measurements reveal that different charge transfer transitions borrow intensity from the localized excitation to different extents. By using different excitation wavelengths, the partitioning of the borrowed intensity among the charge transfer transitions of this complex could be evaluated for the first time.Key words: 1,2,4,5-tetracyanobenzene, hexamethylbenzene, donor–acceptor complex, photoinduced electron transfer, photoselection.

Time-Resolved X-Ray Absorption of An Amorphous Si Foil During Pulsed Laser Irradiation

1985 ◽  
Vol 51 ◽  
Author(s):  
Kouichi Murakami ◽  
Hans C. Gerritsen ◽  
Hedser Van Brug ◽  
Fred Bijkerk ◽  
Frans W. Saris ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Direct Evidence ◽  
Pulsed Laser ◽  
Time Resolved ◽  
Edge Structure ◽  
X Ray ◽  
Nanosecond Pulsed Laser ◽  
Amorphous Si ◽  
X Ray Absorption ◽  
Pulsed Laser Irradiation

ABSTRACTWe report time-resolved X-ray absorption and extended X-ray absorption fine structure (EXAFS) measurements on amorphous silicon under nanosecond pulsed-laser irradiation. Each measurement was performed with one laser shot in the X-ray energy range from 90 to 300 eV. An X-ray absorption spectrum for induced liquid Si (liq*Si) was first observed above an energy density of 0.17 J/cm2. It differs significantly from the spectrum for amorphous Si and characteristically shows the disappearance of the Si-L(II,III) edge structure at around 100 eV. This phenomenon is interpreted in terms of a significant reduction in the 3s-like character of the unfilled part of the conduction band of liq*Si compared to that of amorphous Si. This is the first direct evidence that liq*Si has a metallic-like electronic structure. Timeresolved EXAFS results are also discussed briefly.

A Spectrometer for Measuring Time-Resolved Infrared Linear Dichroism Induced by a Small-Amplitude Oscillatory Strain

1988 ◽  
Vol 42 (2) ◽  
pp. 203-216 ◽  
Author(s):  
Isao Noda ◽  
A. E. Dowrey ◽  
Curtis Marcott
Keyword(s):  
Functional Groups ◽  
Small Amplitude ◽  
Linear Dichroism ◽  
Spectroscopic Technique ◽  
Time Resolved ◽  
Optical Signals ◽  
Dynamic Variations ◽  
Temporal Relationships ◽  
Atactic Polystyrene ◽  
The Individual

A spectrometer for detecting dynamic infrared linear dichroism (DIRLD) induced by a small-amplitude oscillatory strain is described. The strain-induced dynamic variations of absorbance and linear dichroism, as well as the normal static absorbance and dichroism, are measured simultaneously as functions of IR wavenumber, temperature, and strain frequency. The phase (temporal) relationships between the dynamic optical signals and the applied strain are also obtained. The instrument is sensitive enough to detect dynamic optical signals on the order of 10−4 absorbance units with a time resolution of about 14 μs. The dynamic dichroism signals arise from the strain-induced temporary reorientation of dipole-transition moments associated with the molecular vibrations of chemical functional groups. Both the rate and extent of reorientations are strongly influenced by the local molecular environment of the functional groups. Because of the specificity of IR absorbance bands to the individual submolecular structures, DIRLD spectroscopy is especially suited for the study of the intra- and intermolecular interactions and the detection of subtle changes in the local molecular environment. Example DIRLD spectra of atactic polystyrene are presented to demonstrate the potential utility of this spectroscopic technique.

Time-resolved resonance study of dioxygen reduction by cytochrome oxidase

1997 ◽  
Vol 67 (1-4) ◽  
pp. 6
Author(s):  
T. Kitagawa ◽  
T. Ogura ◽  
S. Hirota ◽  
D.A. Proshlyakov ◽  
J. Matysik ◽  
...  
Keyword(s):  
Cytochrome Oxidase ◽  
Time Resolved ◽  
Dioxygen Reduction
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