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Simone Techert - One of the best experts on this subject based on the ideXlab platform.
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Current developments in Time-Resolved X-Ray Diffraction
Crystallography Reviews, 2006Co-Authors: Simone TechertAbstract:In Time-Resolved X-Ray Diffraction (TR-XRD), two different entities can be investigated as a function of time: the structural response function of a system upon photoexcitation and/or the population changes of short-living intermediates during the time course of a reaction. The time scales of these response functions might vary between hours and picoseconds, depending on the effects measured. By correlating the time evolution of structural changes with varying optical properties, it is possible to derive structure–function relationships in a time-dependent manner. The time-dependence of these relationships and the development of relevant methodologies is a major current interest in our group. Systems under investigation are organic materials with optical functionalities (molecular crystals, electron donor–acceptor systems) and solid state reactions (such as topochemical reactions)
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Experimental requirements for light-induced reactions in powders investigated by Time-Resolved X-Ray Diffraction
Journal of Synchrotron Radiation, 2004Co-Authors: Jav Davaasambuu, Pierrick Durand, Simone TechertAbstract:A general outline of how to perform a light-excited Time-Resolved Diffraction experiment by applying the optical pump/X-Ray probe technique is given. Owing to the difference in penetration depths between the optical light (laser) pump and the X-Ray probe, only specific or specially designed crystalline systems can be investigated, so special requirements have to be fulfilled concerning the sample and its compartments. A summary of the experimental conditions of optical pump/X-Ray probe experiments is presented, emphasizing why the use of powder Diffraction is a useful and necessary X-Ray technique for this kind of experiment. The possibilities and bottlenecks of Time-Resolved X-Ray Diffraction on the picosecond time scale will be demonstrated in the powder Diffraction studies of N,N-dimethylaminobenzonitrile and N,N-diisopropylaminobenzonitrile, where the photo-induced structural changes of these molecular organic systems have been studied as a function of time.
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First-, second- and third-order correlation function in Time-Resolved X-Ray Diffraction experiments
Journal of Applied Crystallography, 2004Co-Authors: Simone TechertAbstract:In the past decade, sustained progress has been made in the field of Time-Resolved X-Ray Diffraction and photocrystallography. Laser systems have been developed rapidly, and the combination of pulsed laser sources with pulsed X-Ray sources, particularly by using synchrotron X-Ray radiation and X-Rays generated by plasma sources, has made the application of pump-probe schemes routine. So far, however, most studies have been focused on two questions: (i) the refinement of structural changes during the course of a reaction, and (ii) possible relations between transient structural changes and the intermediates found by optical spectroscopy. In this work, a kinetic description for different time laws in Time-Resolved X-Ray Diffraction experiments is derived in the framework of time-dependent correlation functions. The derived time laws were applied to Time-Resolved studies on a [2+2] photodimerization and a reversible reaction undergoing structural reorganization.
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First investigations of the kinetics of the topochemical reaction of p-formyl-trans-cinnamic acid by Time-Resolved X-Ray Diffraction
Faraday Discussions, 2002Co-Authors: G. Busse, Th. Tschentscher, Michael Wulff, Bernd Frederichs, Anton Plech, Simone TechertAbstract:Under UV irradiation p-formyl-trans-cinnamic acid (p-FCA) crystals in the β-phase dimerise irreversibly to solid 4,4′-diformyl-β-truxinic acid. The experimental conditions were chosen in such a way (non-aqueous environment and room temperature) that the product formed is amorphous. The kinetics of this bimolecular reaction, which has not yet been characterised, was investigated by picosecond Time-Resolved X-Ray Diffraction. From the experimental results a mechanism for this topochemical reaction is proposed including two observed time constants, one less than 100 ps and another of several seconds. The feasibility of investigating this class of substances by Time-Resolved X-Ray Diffraction from third generation synchrotron sources and future free-electron lasers is discussed.
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First investigations of the kinetics of the topochemical reaction of p-formyl-trans-cinnamic acid by Time-Resolved X-Ray Diffraction
Faraday discussions, 2002Co-Authors: G. Busse, Th. Tschentscher, Michael Wulff, Bernd Frederichs, Anton Plech, Simone TechertAbstract:Under UV irradiation p-formyl-trans-cinnamic acid (p-FCA) crystals in the beta-phase dimerise irreversibly to solid 4,4'-diformyl-beta-truxinic acid. The experimental conditions were chosen in such a way (non-aqueous environment and room temperature) that the product formed is amorphous. The kinetics of this bimolecular reaction, which has not yet been characterised, was investigated by picosecond Time-Resolved X-Ray Diffraction. From the experimental results a mechanism for this topochemical reaction is proposed including two observed time constants, one less than 100 ps and another of several seconds. The feasibility of investigating this class of substances by Time-Resolved X-Ray Diffraction from third generation synchrotron sources and future free-electron lasers is discussed.
Michael Wulff - One of the best experts on this subject based on the ideXlab platform.
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Observation of the shock-induced β-Sn to b.c.t.-Sn transition using Time-Resolved X-Ray Diffraction.
Journal of Synchrotron Radiation, 2019Co-Authors: Richard Briggs, R. Torchio, A. Sollier, F. Occelli, Laurent Videau, N. Kretzschmar, Michael WulffAbstract:Time-Resolved X-Ray Diffraction measurements have been carried out on dynamically compressed Sn up to a maximum pressure of ∼13 GPa at the European Synchrotron Radiation Facility. The phase transition from β-Sn to body-centered tetragonal (b.c.t.) Sn has been observed using synchrotron X-Ray Diffraction for the first time undergoing shock compression and release. Following maximum compression, the sample releases to lower pressures for several nanoseconds until the reverse transition occurs. The data are in good agreement with previous shock boundaries that indicate that the β-Sn phase is stable ∼2 GPa higher than the static boundary upon compression and the b.c.t.-Sn phase is stable ∼1 GPa lower upon release. The transition to the high-pressure phase reveals a loss of texture in the X-Ray Diffraction data from the `quasi' single-crystal β-Sn structure to a more powder-like Debye–Scherrer ring.
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Successive Dynamical Steps of Photoinduced Switching of a Molecular Fe(III) Spin-Crossover Material by Time-Resolved X-Ray Diffraction
Physical Review Letters, 2015Co-Authors: Maciej Lorenc, Michael Wulff, Johan Hébert, Marie-laure Boillot, Elzbieta Trzop, Hervé Cailleau, Servol Marina, Emanuele Pontecorvo, Marylise Buron-le Cointe, Marina Servol, Nicolas Moisan, Lorenc Maciej, Cailleau Hervé, Koshihara Shin-Ya, Wulff Michaël, Pontecorvo Emanuele, Moisan Nicolas, Hébert Johan, Trzop Elzbieta, Buron-Le Cointe Marylise, Boillot Marie-Laure, Collet EricAbstract:We investigate the out-of-equilibrium switching dynamics of a molecular Fe(III) spin-crossover solid triggered by a femtosecond laser flash. The Time-Resolved X-Ray Diffraction and optical results show that the dynamics span from subpicosecond local photoswitching followed by volume expansion (nanosecond) and thermal switching (microsecond). We present a physical picture of the consecutive steps in the photoswitching of molecular materials.
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The c-axis thermal conductivity of graphite film of nanometer thickness measured by time resolved X-Ray Diffraction
Applied Physics Letters, 2012Co-Authors: Maher Harb, Michael Wulff, A. Jurgilaitis, Henrik Enquist, C. Von Korff Schmising, Ivan Maximov, Petr V. Shvets, Alexander N. Obraztsov, D. Khakhulin, Jörgen LarssonAbstract:We report on the use of time resolved X-Ray Diffraction to measure the dynamics of strain in laser-excited graphite film of nanometer thickness, obtained by chemical vapour deposition (CVD). Heat transport in the CVD film is simulated with a 1-dimensional heat diffusion model. We find the experimental data to be consistent with a c-axis thermal conductivity of ∼0.7 W m−1 K−1. This value is four orders of magnitude lower than the thermal conductivity in-plane, confirming recent theoretical calculations of the thermal conductivity of multilayer graphene.
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Recombination of photodissociated iodine: A Time-Resolved X-Ray-Diffraction study
Journal of Chemical Physics, 2006Co-Authors: Michael Wulff, S. Bratos, F. Mirloup, Maciej Lorenc, Rodolphe Vuilleumier, Q. Kong, Anton Plech, H. IheeAbstract:A Time-Resolved X-Ray-Diffraction experiment is presented that aims to study the recombination of laser-dissociated iodine molecules dissolved in CCl4. This process is monitored over an extended time interval from pico- to microseconds. The variations of atom-atom distances are probed with a milliangstrom resolution. A recent theory of Time-Resolved X-Ray Diffraction is used to analyze the experimental data; it employs the correlation function approach of statistical mechanics. The most striking outcome of this study is the experimental determination of time-dependent I-I atom-atom distribution functions. The structure of the CCl4 solvent changes simultaneously; the solvent thus appears as a reaction partner rather than an inert medium hosting it. Thermal expansion of the system is nonuniform in time, an effect due to the presence of the acoustic horizon. One concludes that a Time-Resolved X-Ray Diffraction permits real-time visualization of solvent and solute motions during a chemical reaction.
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First investigations of the kinetics of the topochemical reaction of p-formyl-trans-cinnamic acid by Time-Resolved X-Ray Diffraction
Faraday Discussions, 2002Co-Authors: G. Busse, Th. Tschentscher, Michael Wulff, Bernd Frederichs, Anton Plech, Simone TechertAbstract:Under UV irradiation p-formyl-trans-cinnamic acid (p-FCA) crystals in the β-phase dimerise irreversibly to solid 4,4′-diformyl-β-truxinic acid. The experimental conditions were chosen in such a way (non-aqueous environment and room temperature) that the product formed is amorphous. The kinetics of this bimolecular reaction, which has not yet been characterised, was investigated by picosecond Time-Resolved X-Ray Diffraction. From the experimental results a mechanism for this topochemical reaction is proposed including two observed time constants, one less than 100 ps and another of several seconds. The feasibility of investigating this class of substances by Time-Resolved X-Ray Diffraction from third generation synchrotron sources and future free-electron lasers is discussed.
Peter M. Rentzepis - One of the best experts on this subject based on the ideXlab platform.
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Ultrafast structural dynamics studied by kilohertz Time-Resolved X-Ray Diffraction
Chinese Physics B, 2015Co-Authors: Guo Xin, Peter M. Rentzepis, Jiang Zhou-ya, Chen Long, Chen Li-ming, Xin Jian-guo, Chen JieAbstract:Ultrashort multi-ke V X-Ray pulses are generated by electron plasma produced by the irradiation of femtosecond pulses on metals. These sub-picosecond X-Ray pulses have extended the field of X-Ray spectroscopy into the femtosecond time domain. However, pulse-to-pulse instability and long data acquisition time restrict the application of ultrashort X-Ray systems operating at low repetition rates. Here we report on the performance of a femtosecond laser plasma-induced hard X-Ray source that operates at 1-k Hz repetition rate, and provides a flux of 2.0 × 1010 photons/s of Cu Kαradiation. Using this system for Time-Resolved X-Ray Diffraction experiments, we record in real time, the transient processes and structural changes induced by the interaction of 400-nm femtosecond pulse with the surface of a 200-nm thick Au(111) single crystal.
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Laser-Induced Transient Structural Changes in Ag(111) Studied by Time Resolved X-Ray Diffraction
MRS Proceedings, 2013Co-Authors: Jie Chen, Peter M. RentzepisAbstract:ABSTRACTThe transient lattice changes on the Ag(111) crystal due to acoustic wave propagation after excitation with femtosecond pulses was studied by means of time resolved X-Ray Diffraction. The lattice disorder after UV irradiation is detected by changes of the XRD rocking curve shift, broadening, and total Diffraction intensity as a function of time. We have observed a blast force formed within two picoseconds after fs UV irradiation. Experimental results show an initial lattice contraction followed by lattice expansion that propagates with sound velocity.
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Coherent Acoustic Wave Oscillations and Melting on Ag(111) Surface by Time Resolved X-Ray Diffraction
Applied Physics Letters, 2012Co-Authors: Jie Chen, Jau Tang, Peter M. RentzepisAbstract:The transient structural disorder on the Ag(111) crystal after excitation with fs pulses was studied by means of time resolved X-Ray Diffraction. The lattice disorder after UV irradiation is detected by changes in the XRD rocking curve including peak shift, broadening, and total Diffraction intensity. We have observed blast and pressure wave formation and melting and mosaic crystal formation during re-crystallization. A blast force was formed within 2 ps after fs UV irradiation of the crystal, followed lattice contraction, melting phase transition, and mosaic crystal formation as the temperature decreases below melting. The experimental data are also supported by theoretical simulations.
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Laser-induced transient structure and stress in a platinum(111) crystal studied by Time-Resolved X-Ray Diffraction
Journal of Applied Crystallography, 1999Co-Authors: P. Chen, Ivan V. Tomov, Peter M. RentzepisAbstract:Nanosecond Time-Resolved X-Ray Diffraction has been employed to study the transient structure deformation of a Pt(111) crystal induced by laser pulse heating. A direct-imaging X-Ray CCD system with high spatial resolution allowed the detection of structural changes of the order of 10−3 Å. The time evolution of lattice strain was measured with 12 ns resolution. The lattice spacings were found to suffer a transient change from 2.2653 to 2.2695 (10) Å, and the strain reached its maximum value 10 ns after laser irradiation.
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Lattice dynamics of laser-heated GaAs crystals by means of Time-Resolved X-Ray Diffraction
The Journal of Physical Chemistry A, 1999Co-Authors: Peilin Chen, Ivan V. Tomov, Peter M. RentzepisAbstract:Nanosecond Time-Resolved X-Ray Diffraction has been employed to study the transient lattice structure of GaAs crystals induced by laser pulse heating. The time evolution of lattice spacing changes was measured with 12 ns resolution. A direct imaging X-Ray CCD system with high spatial resolution allowed for the detection of transient structural changes on the order of 5 {times} 10{sup {minus}4} {angstrom}.
Kazutaka G. Nakamura - One of the best experts on this subject based on the ideXlab platform.
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probed by Time-Resolved X-Ray Diffraction
2017Co-Authors: Kazutaka G. Nakamura, Yoichiro Hironaka, Hiroaki Kishimura, Ken-ichi KondoAbstract:Structural dynamics of 3OOps laser irradiated semiconductor is studied by means of picosecond Time-Resolved X-RayDiffraction. Picosecond pulsed X rays are generated by focusing intense femtosecond laser beams onto metal target.Time-Resolved X-Ray Diffraction is performed by a laser pump and X-Ray probe technique. Lattice expansion due toacoustic phonon generation and propagation is observed in a silicon crystal in a single laser shot experiment at laserenergy density of 1.0 J/cm2. On the other hand, in a multiple laser shot experiment, lattice compression due to lasershock compression is observed at l4 J/cm2.Keywords: femtosecond laser, X-Ray pulse, Time-Resolved X-Ray Diffraction, structural dynamics
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Structural Dynamics of Polycrystals under Shock Compression Observed via Nanosecond Time-Resolved X-Ray Diffraction
MRS Online Proceedings Library, 2013Co-Authors: Kazutaka G. Nakamura, Kouhei Ichiyanagi, Nobuaki Kawai, Shin-ichi AdachiAbstract:Dynamics of structural phase transition in polycrystalline samples (tetragonal stabilized zirconia and bismuth) under laser-shock compression has been studied using nanosecond Time-Resolved X-Ray Diffraction technique based on synchrotron radiation. Tetragonal zirconia shows the structural phase transition to the monoclinic phase within 20 ns during shock compression without any intermediate and reverts back to the tetragonal phase during pressure release. Bismuth shows more complex phase transition dynamics. The Bi-I phase, which is the stable phase at ambient pressure and temperature, transfers to Bi-V phase within 4 ns under shock compression and gradually reverts back following the path of Bi-V →Bi-III → Bi-II → Bi-I within 30 ns during pressure release.
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Femtosecond Time-Resolved X-Ray Diffraction from optical coherent phonons in CdTe(111) crystal
Applied Physics Letters, 2008Co-Authors: Kazutaka G. Nakamura, Yoichiro Hironaka, Jun Irisawa, Kunie Ishioka, Satoshi Ishii, Shusei Ishitsu, Masato Shiokawa, Hiroshi Takahashi, K. Dharmalingam, Masahiro KitajimaAbstract:Coherent phonons excited in a CdTe(111) crystal by 70 fs laser irradiation have been investigated by femtosecond Time-Resolved X-Ray Diffraction. The longitudinal optical phonon with a frequency of approximately 5 THz near the Brillouin zone center has been detected as modulation in intensities of X-Ray Diffraction. Atomic displacement in the [111] direction in the coherent longitudinal optical phonon has been estimated.
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Lattice dynamics in two-photon-excited CdS studied by picosecond Time-Resolved X-Ray Diffraction
Physica B: Condensed Matter, 2008Co-Authors: Hiroaki Kishimura, Yoichiro Hironaka, Kazutaka G. NakamuraAbstract:Abstract Lattice dynamics and radiative processes in single-crystal cadmium sulfide induced by two-photon excitation with a femtosecond laser are investigated. The development of lattice expansion is directly observed by picosecond Time-Resolved X-Ray Diffraction. The obtained lattice dynamics are explained on the basis of a thermally induced impulsive-strain model. The model calculation indicates that two- and more-photon absorption processes occur and that reflectivity rapidly increases under laser irradiation. In photoluminescence spectroscopy, the spectra for TW cm−2 excitation are shifted to lower energy and show an additional shoulder at 2.35 eV. Furthermore, emission due to Fabry–Perot laser modes with self-formed cavities was observed under 11 TW cm−2 excitation. The discrepancy between carrier densities deduced from the lattice expansion and the PL spectra indicates that the predominant process at a higher carrier density is not radiative recombination, but Auger recombination followed by lattice heating.
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Micromosaic formation in laser-irradiated Si probed by picosecond Time-Resolved X-Ray Diffraction
Physical Review B, 2006Co-Authors: Hiroaki Kishimura, Kazutaka G. Nakamura, Yoichiro Hironaka, Ken-ichi Kondo, Yasuhisa H. Okano, Hiroto Morishita, Toshiyuki AtouAbstract:The transient lattice behavior of single-crystal Si(111) under 300 ps laser irradiation has been observed by Time-Resolved X-Ray Diffraction. At first, the rocking curves of the laser-irradiated Si(111) have a higher-angle-shifted component. The higher-angle component is attributed to lattice compression, which is induced by laser ablation. The maximum lattice strain is estimated at 5.6%, which is larger than the Hugoniot elastic limit for Si(111). After 1000 ps, a broadening of the main peak was recorded. In addition, the rocking curve of a recovered sample is clearly broader than that of a pristine sample. Reciprocal space mapping for the recovered sample shows that the lattice spacing of the recovered sample does not change from that of the pristine sample, whereas lattice planes are misoriented. The results of Time-Resolved measurement and the assessment of the recovered sample indicate that mosaic blocks with inclined orientations are induced by laser-driven elastic compression and the subsequent pressure release, rather than plastic deformation.
Anton Plech - One of the best experts on this subject based on the ideXlab platform.
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Recombination of photodissociated iodine: A Time-Resolved X-Ray-Diffraction study
Journal of Chemical Physics, 2006Co-Authors: Michael Wulff, S. Bratos, F. Mirloup, Maciej Lorenc, Rodolphe Vuilleumier, Q. Kong, Anton Plech, H. IheeAbstract:A Time-Resolved X-Ray-Diffraction experiment is presented that aims to study the recombination of laser-dissociated iodine molecules dissolved in CCl4. This process is monitored over an extended time interval from pico- to microseconds. The variations of atom-atom distances are probed with a milliangstrom resolution. A recent theory of Time-Resolved X-Ray Diffraction is used to analyze the experimental data; it employs the correlation function approach of statistical mechanics. The most striking outcome of this study is the experimental determination of time-dependent I-I atom-atom distribution functions. The structure of the CCl4 solvent changes simultaneously; the solvent thus appears as a reaction partner rather than an inert medium hosting it. Thermal expansion of the system is nonuniform in time, an effect due to the presence of the acoustic horizon. One concludes that a Time-Resolved X-Ray Diffraction permits real-time visualization of solvent and solute motions during a chemical reaction.
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Time resolved X-Ray Diffraction and non-thermal inelastic X-Ray scattering
AIP Conference Proceedings, 2004Co-Authors: Peter Sondhauss, Anton Plech, Justin S. Wark, Jörgen Larsson, Michael Harbst, G.a. Naylor, K. Scheidt, Ola Synnergren, M. WulfAbstract:Atomic processes like e.g. molecular vibrations, chemical reactions or phase transitions happen on picosecond down to femtosecond time scales. Novel pulsed X-Ray sources or alternatively ultrafast X-Ray detectors allow the investigation of these processes in real time. A powerful tool for the investigation of the dynamics in crystalline materials is time resolved X-Ray Diffraction (TRXD). As an example the authors present the measurement of "phonon branch folding" in a GaSb/InAs superlattice by means of TRXD. In the second part we look forward to the near future of TRXD. X-Ray scattering from coherent acoustic and optical phonons has recently become describable within the framework of dynamical Diffraction theory. This theory provides the means for the detailed modeling of how various lattice dynamical processes manifest themselves in the diffracted X-Ray signal. Simulations are presented showing the effects of coherent acoustic and optical phonons on the rocking curve of quartz (010) (Less)
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First investigations of the kinetics of the topochemical reaction of p-formyl-trans-cinnamic acid by Time-Resolved X-Ray Diffraction
Faraday Discussions, 2002Co-Authors: G. Busse, Th. Tschentscher, Michael Wulff, Bernd Frederichs, Anton Plech, Simone TechertAbstract:Under UV irradiation p-formyl-trans-cinnamic acid (p-FCA) crystals in the β-phase dimerise irreversibly to solid 4,4′-diformyl-β-truxinic acid. The experimental conditions were chosen in such a way (non-aqueous environment and room temperature) that the product formed is amorphous. The kinetics of this bimolecular reaction, which has not yet been characterised, was investigated by picosecond Time-Resolved X-Ray Diffraction. From the experimental results a mechanism for this topochemical reaction is proposed including two observed time constants, one less than 100 ps and another of several seconds. The feasibility of investigating this class of substances by Time-Resolved X-Ray Diffraction from third generation synchrotron sources and future free-electron lasers is discussed.
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First investigations of the kinetics of the topochemical reaction of p-formyl-trans-cinnamic acid by Time-Resolved X-Ray Diffraction
Faraday discussions, 2002Co-Authors: G. Busse, Th. Tschentscher, Michael Wulff, Bernd Frederichs, Anton Plech, Simone TechertAbstract:Under UV irradiation p-formyl-trans-cinnamic acid (p-FCA) crystals in the beta-phase dimerise irreversibly to solid 4,4'-diformyl-beta-truxinic acid. The experimental conditions were chosen in such a way (non-aqueous environment and room temperature) that the product formed is amorphous. The kinetics of this bimolecular reaction, which has not yet been characterised, was investigated by picosecond Time-Resolved X-Ray Diffraction. From the experimental results a mechanism for this topochemical reaction is proposed including two observed time constants, one less than 100 ps and another of several seconds. The feasibility of investigating this class of substances by Time-Resolved X-Ray Diffraction from third generation synchrotron sources and future free-electron lasers is discussed.
