Apparatus for the measurement of the electronic excited-state structure of single crystals using X-ray diffraction

1994 ◽  
Vol 27 (5) ◽  
pp. 727-732 ◽  
Author(s):  
M. A. White ◽  
M. R. Pressprich ◽  
P. Coppens ◽  
D. D. Coppens
Keyword(s):  
Excited States ◽  
Modulation Method ◽  
State Structure ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Electronic Excited States ◽  
Structure Factors ◽  
Counting Statistics ◽  
Mechanical Chopper

Instrumentation for measuring the X-ray diffraction pattern of optically excited crystals is described. The experiment uses a high-power (~1 W) laser and a single-crystal diffractometer equipped with a helium cryostat (T < 70 K). The laser beam is modulated by a mechanical chopper and the diffraction signal gated in synchronization with the chopper phase. The modulation method is capable of observing small changes (down to about 0.01%) in the structure factors upon excitation of a fraction of the molecules in the crystal, given adequate counting statistics. The technique can be used for relatively long lived electronic excited states (τ ≃ 0.1–10 ms). The optical system is also suitable for time-resolved measurements using the time structure of synchrotron radiation.

The structure of short-lived excited states of molecular complexes by time-resolved X-ray diffraction

2005 ◽  
Vol 61 (2) ◽  
pp. 162-172 ◽  
Author(s):  
Philip Coppens ◽  
Ivan I. Vorontsov ◽  
Tim Graber ◽  
Milan Gembicky ◽  
Andrey Yu. Kovalevsky
Keyword(s):  
Excited States ◽  
Molecular Complexes ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray

STE LUMINESCENCE FROM THE SUPERSTRUCTURE PHASE Na6CdCl8 IN NaCl:Cd2+ CRYSTALS

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3885-3888
Author(s):  
H. NAKAGAWA ◽  
S. KISHIGAMI
Keyword(s):  
Thermal Treatment ◽  
Optical Absorption ◽  
Excited States ◽  
Lattice Relaxation ◽  
Relaxation Processes ◽  
X Ray Diffraction ◽  
Detailed Structure ◽  
Broad Absorption ◽  
X Ray ◽  
Electronic Excited States

Optical Absorption and luminescence studies have been conducted in Nacl crystals contining various amounts of CdCl 2 in order to investigate the electronic excited states and their lattice relaxation processes in Suzuki superstructure lattice. X-ray diffraction measurements have been also made to confirm the presence of the Suzuki phase and to determine its detailed structure. Two broad absorption structures are observed in the energy region of 4.25-5.0 eV (LE) and of 5.0-6.0 eV (HE). With excitation in the LE region, three emission bands are produced at 2.64 (BG), 3.14 (V) and 3.56(UV1)eV. They are attribute to the Cd 2+ impurity-related centers. In case of excitation in the HE region, two prominent emission bands are observed at 2.76 (B) and 2.08 (Y) eV. Taking into consideration the experimental results of X-ray diffraction, thermal treatment and Cd 2+ concentration dependence, the B- and Y-emission are connected to the STE in Suzuki lattice of small and large sizes, respectively.

Excited-state structure by time-resolved X-ray diffraction

2002 ◽  
Vol 58 (2) ◽  
pp. 133-137 ◽  
Author(s):  
Christopher D. Kim ◽  
Sebastien Pillet ◽  
Guang Wu ◽  
Wilfred K. Fullagar ◽  
Philip Coppens
Keyword(s):  
Excited State ◽  
State Structure ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray

Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

1983 ◽  
Vol 41 ◽  
pp. 446-447
Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Heavy Atom ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Salt Solutions ◽  
X Ray ◽  
Isomorphous Replacement ◽  
Structure Factors ◽  
Diffraction Structure ◽  
The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

Highlights in the history of X-ray topography1

1995 ◽  
Vol 210 (6) ◽  
Author(s):  
A. R. Lang
Keyword(s):  
Magnetic Domain ◽  
Diffraction Theory ◽  
Dislocation Loops ◽  
X Ray Diffraction ◽  
X Ray ◽  
Domain Structures ◽  
Structure Factors ◽  
History Of ◽  
Dislocation Sources ◽  
Non Destructive

AbstractX-ray topography provides a non-destructive method of mapping point-by-point variations in orientation and reflecting power within crystals. The discovery, made by several workers independently, that in nearly perfect crystals it was possible to detect individual dislocations by X-ray diffraction contrast started an epoch of rapid exploitation of X-ray topography as a new, general method for assessing crystal perfection. Another discovery, that of X-ray Pendellösung, led to important theoretical developments in X-ray diffraction theory and to a new and precise method for measuring structure factors on an absolute scale. Other highlights picked out for mention are studies of Frank-Read dislocation sources, the discovery of long dislocation helices and lines of coaxial dislocation loops in aluminium, of internal magnetic domain structures in Fe-3 wt.% Si, and of stacking faults in silicon and natural diamonds.

scholarly journals Direct observations of shock-induced melting in a porous solid using time-resolved x-ray diffraction

2020 ◽  
Vol 4 (6) ◽  
Author(s):  
A. Mandal ◽  
B. J. Jensen ◽  
M. C. Hudspeth ◽  
S. Root ◽  
R. S. Crum ◽  
...  
Keyword(s):  
Porous Solid ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Direct Observations

scholarly journals Bulk modulus of H2O across the ice VII–ice X transition measured by time-resolved x-ray diffraction in dynamic diamond anvil cell experiments

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
A. S. J. Méndez ◽  
F. Trybel ◽  
R. J. Husband ◽  
G. Steinle-Neumann ◽  
H.-P. Liermann ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Diamond Anvil Cell ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Diamond Anvil

Time-resolved isothermal crystallization of absorbable PGA-co-PLA copolymer by synchrotron small-angle X-ray scattering and wide-angle X-ray diffraction

Polymer ◽  
2001 ◽  
Vol 42 (21) ◽  
pp. 8965-8973 ◽  
Author(s):  
Zhi-Gang Wang ◽  
Xuehui Wang ◽  
Benjamin S. Hsiao ◽  
Saša Andjelić ◽  
Dennis Jamiolkowski ◽  
...  
Keyword(s):  
Small Angle ◽  
Isothermal Crystallization ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering
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