scholarly journals Probing Electronic Strain Generation by Separated Electron-Hole Pairs Using Time-Resolved X-ray Scattering

2019 ◽  
Vol 9 (22) ◽  
pp. 4788
Author(s):  
Sooheyong Lee ◽  
Wonhyuk Jo ◽  
Anthony D. DiChiara ◽  
Timothy P. Holmes ◽  
Stephen Santowski ◽  
...  
Keyword(s):  
Charge Carriers ◽  
Excess Charge ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
Time Resolved ◽  
Transient Conditions ◽  
Strain Measurements ◽  
X Ray ◽  
X Ray Scattering ◽  
Photoinduced Charge

Photogeneration of excess charge carriers in semiconductors produces electronic strain. Under transient conditions, electron-hole pairs may be separated across a potential barrier. Using time-resolved X-ray diffraction measurements across an intrinsic AlGaAs/n-doped GaAs interface, we find that the electronic strain is only produced by holes, and that electrons are not directly observable by strain measurements. The presence of photoinduced charge carriers in the n-doped GaAs is indirectly confirmed by delayed heat generation via recombination.

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

A method of material design for systematic absence of X-ray diffraction

2010 ◽  
Vol 25 (S1) ◽  
pp. S48-S51
Author(s):  
Huan-hua Wang
Keyword(s):  
Solid Solution ◽  
Structure Factor ◽  
Material Design ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
Xrd Pattern ◽  
X Ray ◽  
X Ray Scattering ◽  
Calculation Process

Materials with systematic absence of X-ray diffraction (XRD) peaks are desirable for conducting some special researches using X-ray diffraction or time-resolved X-ray scattering. This paper proposes a method for designing this kind of materials. It utilizes solid solution to reduce the structure factor of a selected reflection to zero by choosing proper components and their contents to let the reflection amplitudes from different atomic layers in a unit cell of the solid solution cancel each other completely. This method on how to select a solid solvent and how to calculate its content was illustrated using SrTiO3 as an example. A solid solution Sr1−xCaxTiO3 with a systematic absence of the (001) diffraction can be designed, and the value of x can be determined to be x=0.54 using an iteration calculation process. This result was verified by the experimental XRD pattern of a Sr0.46Ca0.54TiO3 sample.

scholarly journals On the possibility of the Observation of Intramolecular Reaction Dynamics in Liquids by Time-resolved X-ray Scattering

2002 ◽  
Vol 216 (5) ◽  
Author(s):  
S. Techert ◽  
S. Schmatz
Keyword(s):  
Gas Phase ◽  
Free Electron Laser ◽  
Structural Changes ◽  
Reaction Dynamics ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Trans Stilbene

The feasibility of time-resolved structural studies using pulsed X-ray radiation from a 3rd generation synchrotron is discussed and compared with scattering experiments which might be possible with a future free electron laser (X-FEL). As an example, it is shown that the structural changes during the isomerisation process of trans-stilbene into cis-stilbene can be observed using time-resolved X-ray diffraction in the gas-phase as well as in solution.

New Insight of Isothermal Melt Crystallization in Poly(aryl ether ether ketone) via Time-Resolved Simultaneous Small-Angle X-ray Scattering/Wide-Angle X-ray Diffraction Measurements

1995 ◽  
Vol 28 (20) ◽  
pp. 6931-6936 ◽  
Author(s):  
Benjamin S. Hsiao ◽  
Bryan B. Sauer ◽  
Ravi K. Verma ◽  
H. Gerhard Zachmann ◽  
Soenke Seifert ◽  
...  
Keyword(s):  
Small Angle ◽  
Wide Angle ◽  
Melt Crystallization ◽  
Aryl Ether ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Ether Ether Ketone ◽  
Ether Ketone

A time-resolved SAXS study on the crystalline morphology of long-term stored isotactic polypropylene

2004 ◽  
Vol 37 (2) ◽  
pp. 295-299 ◽  
Author(s):  
Jun-Ting Xu ◽  
Yu-Jin Zhang ◽  
Zhi-Qiang Fan
Keyword(s):  
Isotactic Polypropylene ◽  
Crystal Form ◽  
Crystalline Morphology ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Time Resolved ◽  
Crystal Forms ◽  
X Ray ◽  
X Ray Scattering

The crystalline morphology of a long-term stored metallocene isotactic polypropylene (mPP) has been studied with time-resolved small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD), and compared with that of the freshly crystallized sample. It was found that both α and γ crystal forms occur in the long-term stored mPP, whereas freshly crystallized mPP contains only the α crystal form. Double SAXS peaks were observed for the long-term stored mPP, which can be assigned to the α and γ crystals. Based on the SAXS result, it is inferred that the crystal stacks of the α and γ forms in the long-term stored mPP are arranged according to the block mode.

Time-Resolved Saxs and Waxs Studies on Ordering Process in Oriented Crystallization of Polymers

1986 ◽  
Vol 79 ◽  
Author(s):  
Kenji Saijo ◽  
Takeji Hashimoto
Keyword(s):  
Structure Evolution ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Oriented Crystallization ◽  
Polybutadiene Rubber ◽  
Integrated Intensity ◽  
Crystallization Of Polymers ◽  
As Stress

AbstractMechanism and dynamics of the ordering process in oriented crystallization of polymers were investigated by time-resolved small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXS). As a model system for the oriented crystallization, a cross-linked polybutadiene rubber with a high cis-1,4-linkage was chosen, and the structure evolution during the isothermal crystallization was investigated under constant elongations by real time and in situ analyses of the microscopic observables such as long spacing, crystallite size, SAXS integrated intensity, WAXS crystallinity and WAXS line width as well as a macroscopic observable such as stress. The isothermal ordering processes were explored in three different crystallization regimes: crystallization from (i) unoriented melts, (ii) weakly-to-moderately oriented melts and (iii) highly oriented melts.

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

Time-Resolved Cryo-Electron Microscopy of Oscillating Microtubules

1990 ◽  
Vol 48 (1) ◽  
pp. 502-503
Author(s):  
Eva-Maria Mandelkow ◽  
Ron Milligan
Keyword(s):  
Electron Microscopy ◽  
Dynamic Instability ◽  
Entire Solution ◽  
Reaction Scheme ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
A Chain ◽  
Ray Scattering

Microtubules form part of the cytoskeleton of eukaryotic cells. They are hollow libers of about 25 nm diameter made up of 13 protofilaments, each of which consists of a chain of heterodimers of α-and β-tubulin. Microtubules can be assembled in vitro at 37°C in the presence of GTP which is hydrolyzed during the reaction, and they are disassembled at 4°C. In contrast to most other polymers microtubules show the behavior of “dynamic instability”, i.e. they can switch between phases of growth and phases of shrinkage, even at an overall steady state [1]. In certain conditions an entire solution can be synchronized, leading to autonomous oscillations in the degree of assembly which can be observed by X-ray scattering (Fig. 1), light scattering, or electron microscopy [2-5]. In addition such solutions are capable of generating spontaneous spatial patterns [6].In an earlier study we have analyzed the structure of microtubules and their cold-induced disassembly by cryo-EM [7]. One result was that disassembly takes place by loss of protofilament fragments (tubulin oligomers) which fray apart at the microtubule ends. We also looked at microtubule oscillations by time-resolved X-ray scattering and proposed a reaction scheme [4] which involves a cyclic interconversion of tubulin, microtubules, and oligomers (Fig. 2). The present study was undertaken to answer two questions: (a) What is the nature of the oscillations as seen by time-resolved cryo-EM? (b) Do microtubules disassemble by fraying protofilament fragments during oscillations at 37°C?

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