scholarly journals Transient lattice contraction in the solid-to-plasma transition

2016 ◽  
Vol 2 (1) ◽  
pp. e1500837 ◽  
Author(s):  
Ken R. Ferguson ◽  
Maximilian Bucher ◽  
Tais Gorkhover ◽  
Sébastien Boutet ◽  
Hironobu Fukuzawa ◽  
...  
Keyword(s):  
Electronic Excitation ◽  
Condensed Matter ◽  
Structural Evolution ◽  
Dense Matter ◽  
Lattice Contraction ◽  
Van Der Waals Clusters ◽  
X Ray ◽  
Ultrafast Imaging ◽  
Isochorically Heated ◽  
Bond Character

In condensed matter systems, strong optical excitations can induce phonon-driven processes that alter their mechanical properties. We report on a new phenomenon where a massive electronic excitation induces a collective change in the bond character that leads to transient lattice contraction. Single large van der Waals clusters were isochorically heated to a nanoplasma state with an intense 10-fs x-ray (pump) pulse. The structural evolution of the nanoplasma was probed with a second intense x-ray (probe) pulse, showing systematic contraction stemming from electron delocalization during the solid-to-plasma transition. These findings are relevant for any material in extreme conditions ranging from the time evolution of warm or hot dense matter to ultrafast imaging with intense x-ray pulses or, more generally, any situation that involves a condensed matter-to-plasma transition.

scholarly journals Free-Electron X-Ray Laser Measurements of Collisional-Damped Plasmons in Isochorically Heated Warm Dense Matter

2015 ◽  
Vol 115 (11) ◽  
Author(s):  
P. Sperling ◽  
E. J. Gamboa ◽  
H. J. Lee ◽  
H. K. Chung ◽  
E. Galtier ◽  
...  
Keyword(s):  
Free Electron ◽  
Dense Matter ◽  
Warm Dense Matter ◽  
X Ray ◽  
Laser Measurements ◽  
Isochorically Heated

STRUCTURAL EVOLUTION OF EXCEPTIONALLY IRON-DEFICIENT HEMATITE NANOCRYSTALS AS OBSERVED BY IN SITU SYNCHROTRON X-RAY DIFFRACTION

2019 ◽  
Author(s):  
Si Athena Chen ◽  
◽  
Peter Heaney ◽  
Jeffrey E. Post ◽  
Peter J. Eng ◽  
...  
Keyword(s):  
Structural Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Iron Deficient

scholarly journals Effect of tungsten disulfide nanotubes on crystallization of polylactide under uniaxial deformation and annealing

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Fausta Loffredo ◽  
Loredana Tammaro ◽  
Tiziana Di Luccio ◽  
Carmela Borriello ◽  
Fulvia Villani ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Structural Evolution ◽  
Tungsten Disulfide ◽  
Fine Tuning ◽  
Nanocomposite Films ◽  
Uniaxial Deformation ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering

AbstractTungsten disulfide (WS2) nanotubes (NTs) are examined here as a filler for polylactide (PLA) for their ability to accelerate PLA crystallization and for their promising biocompatibility in relevant to biomedical applications of PLA-WS2 nanocomposites. In this work, we have studied the structural and thermal properties of PLA-WS2 nanocomposite films varying the concentration of WS2 NTs from 0 (neat PLA) to 0.6 wt%. The films were uniaxially drawn at 90 °C and annealed at the same temperature for 3 and 10 min. Using wide angle x-ray scattering, Raman spectroscopy and differential scanning calorimetry, we probed the effects of WS2 NT addition on the structure of the PLA films at various stages of processing (unstretched, stretching, annealing). We found that 0.6 wt% of WS2 induces the same level of crystallinity in as stretched PLA-WS2 as annealing in neat PLA for 10 min. These data provide useful insights into the role of WS2 NTs on the structural evolution of PLA-WS2 composites under uniaxial deformation, and extend their applicability to situations where fine tuning of PLA crystallinity is desirable.

scholarly journals X-ray transient absorption reveals the 1Au (nπ*) state of pyrazine in electronic relaxation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Valeriu Scutelnic ◽  
Shota Tsuru ◽  
Mátyás Pápai ◽  
Zheyue Yang ◽  
Michael Epshtein ◽  
...  
Keyword(s):  
Electronic Excitation ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Nonadiabatic Dynamics ◽  
X Ray ◽  
Organic Chromophores ◽  
Dynamics Simulations ◽  
X Ray Absorption ◽  
Structure Calculations

AbstractElectronic relaxation in organic chromophores often proceeds via states not directly accessible by photoexcitation. We report on the photoinduced dynamics of pyrazine that involves such states, excited by a 267 nm laser and probed with X-ray transient absorption spectroscopy in a table-top setup. In addition to the previously characterized 1B2u (ππ*) (S2) and 1B3u (nπ*) (S1) states, the participation of the optically dark 1Au (nπ*) state is assigned by a combination of experimental X-ray core-to-valence spectroscopy, electronic structure calculations, nonadiabatic dynamics simulations, and X-ray spectral computations. Despite 1Au (nπ*) and 1B3u (nπ*) states having similar energies at relaxed geometry, their X-ray absorption spectra differ largely in transition energy and oscillator strength. The 1Au (nπ*) state is populated in 200 ± 50 femtoseconds after electronic excitation and plays a key role in the relaxation of pyrazine to the ground state.

In situ synchrotron small- and wide-angle X-ray study on the structural evolution of Kevlar fiber under uniaxial stretching

RSC Advances ◽  
2016 ◽  
Vol 6 (85) ◽  
pp. 81552-81558 ◽  
Author(s):  
Xiaoyun Li ◽  
Feng Tian ◽  
Ping Zhou ◽  
Chunming Yang ◽  
Xiuhong Li ◽  
...  
Keyword(s):  
Structural Evolution ◽  
Wide Angle ◽  
Uniaxial Stretching ◽  
X Ray ◽  
Kevlar Fiber

In situ SAXS and WAXS study on the structural evolution and mechanism of two different Kevlar fibers during stretching.

scholarly journals Atomic Migration Studies with X-Ray Photon Correlation Spectroscopy

2014 ◽  
Vol 2 ◽  
pp. 73-94 ◽  
Author(s):  
Markus Stana ◽  
Manuel Ross ◽  
Bogdan Sepiol
Keyword(s):  
Low Temperatures ◽  
Short Range ◽  
Short Range Order ◽  
Photon Correlation Spectroscopy ◽  
Condensed Matter ◽  
Correlation Spectroscopy ◽  
Atomic Scale ◽  
Photon Correlation ◽  
X Ray ◽  
Amorphous Systems

The new technique of atomic-scale X-ray Photon Correlation Spectroscopy (aXPCS) makesuse of a coherent X-ray beam to study the dynamics of various processes in condensed matter systems.Particularly atomistic migration mechanisms are still far from being understood in most of intermetallicalloys and in amorphous systems. Special emphasis must be given to the opportunity to measureatomistic diffusion at relatively low temperatures where such measurements were far out of reach withpreviously established methods. The importance of short-range order is demonstrated on the basis ofMonte Carlo simulations.

Structural evolution of NASICON-type Li1+xAlxGe2−x(PO4)3 using in situ synchrotron X-ray powder diffraction

2016 ◽  
Vol 4 (20) ◽  
pp. 7718-7726 ◽  
Author(s):  
Dorsasadat Safanama ◽  
Neeraj Sharma ◽  
Rayavarapu Prasada Rao ◽  
Helen E. A. Brand ◽  
Stefan Adams
Keyword(s):  
Solid Electrolyte ◽  
Diffraction Study ◽  
Powder Diffraction ◽  
Structural Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nasicon Type ◽  
Precursor Glass

In situ synchrotron X-ray diffraction study of the synthesis of solid-electrolyte Li1+xAlxGe2−x(PO4)3 (LAGP) from the precursor glass reveals that an initially crystallized dopant poor phase transforms into the Al-doped LAGP at 800 °C.

scholarly journals Structural Evolution in Wet Mechanically Alloyed Co-Fe-(Ta,W)-B Alloys

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 800
Author(s):  
Vladimír Girman ◽  
Maksym Lisnichuk ◽  
Daria Yudina ◽  
Miloš Matvija ◽  
Pavol Sovák ◽  
...  
Keyword(s):  
Structural Changes ◽  
Magnetic Measurements ◽  
Structural Evolution ◽  
High Energy ◽  
Control Agent ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.

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