Time-resolved Diffraction Measurements Research Articles

Cooperative motion analysis of group II chaperonins at single molecule level using nanocrystal and time-resolved diffraction measurement

Cooperative motion analysis of group II chaperonins at single molecule level using nanocrystal and time-resolved diffraction measurement

Imaging electronic motions in atoms by energy-resolved ultrafast electron diffraction

We propose energy-resolved ultrafast electron diffraction as a means of directly imaging target electronic motions whose space, time, and energy information can be simultaneously retrieved from time-resolved diffraction measurements. The energy-resolved diffraction images are simulated for breathing, wiggling, and hybrid modes of electronic motion in the H atom. The simulations demonstrate the capabilities of ultrafast electron diffraction to image and distinguish different kinds of electronic motion. The theoretical analysis of the scattering process identifies the requirements for time- and state-resolved imaging of electronic motion and provides interpretations of the results.

A fast X-ray detector using silicon avalanche photodiodes of 64-pixel linear array

We have developed a silicon avalanche-photodiode (Si-APD) array detector operated in the linear mode for time-resolved measurements using pulsed synchrotron X-rays. The Si-APD detector had 64 pixels of a linear array, where the pixel size was 100 μm by 200 μm with a 50-μm gap between pixels and a depleted thickness was 10 μm. A nanosecond response of the array detector is extremely valuable for time-resolved X-ray diffraction measurements in the multi-bunch mode operation of a 500M-Hz synchrotron ring. In order to apply the APD detector for the time-resolved diffraction measurements with 2-ns pulse-pair resolving time and a count rate of more than 10 s−1, an ultra fast ASIC has newly been developed for processing a nanosecond-width pulse from each pixel of the Si-APD array. A prototype system had a 10-ns time resolution and a high count-rate of more than 107 s−1/pixel in the first test measurement using synchrotron X-ray beam.

Synchrotron Radiation Study on Time-Resolved Tetragonal Lattice Strain of BaTiO3 under Electric Field

The dynamic response of an intrinsic lattice strain in a tetragonal BaTiO3 single crystal to an electric field is investigated. Time-resolved diffraction measurement using high-energy synchrotron radiation enables us to detect the time dependence of the small change in the tetragonality of BaTiO3 during polarization reversal and piezoelectric vibration after a step like electric field antiparallel to the spontaneous polarization is applied to the sample.

Ultra-high-precision time control system over any long time delay for laser pump and synchrotron x-ray probe experiment

An ultra-high-precision clock system for long time delay has been developed for picosecond time-resolved x-ray diffraction measurements using synchrotron radiation (SR) pulses and synchronized femtosecond laser pulses. The time delay control between pump laser pulse and the probe SR pulse was achieved by combining an in-phase quadrature modulator and a synchronous counter. This method allowed us to change the delay time by a nearly infinite amount while maintaining the precision of +/-8.40 ps. Time-resolved diffraction measurements using the delay control system were demonstrated for precise measurement of an acoustic velocity in a single crystal of gallium arsenide.

Time-resolved diffraction measurements of electric-field-induced strain in tetragonal lead zirconate titanate

The dynamic electric-field-induced strain in piezoelectric ceramics enables their use in a broad range of sensor, actuator, and electronic devices. In piezoelectric ceramics which are also ferroelectric, this macroscopic strain is comprised of both intrinsic (piezoelectric) and extrinsic (non-180° domain switching) strain components. Extrinsic contributions are accompanied by hysteresis, nonlinearity, and fatigue. Though technologically significant, direct measurement of these mechanisms and their relative contributions to the macroscopic response has not yet been achieved at driving frequencies of interest. Here we report measurements of these mechanisms in ceramic lead zirconate titanate during application of subcoercive cyclic driving electric fields using an in-situ stroboscopic neutron diffraction technique. Calculations are made from the diffraction measurements to determine the relative contributions of these different strain mechanisms. During applied electric field square waves of +0.5Ec unipolar and ±0.5Ec bipolar, at 1 Hz, non-180° domain switching is found to contribute 34% and 40% of the macroscopically measured strain, respectively.

Stroboscopic X-Ray Diffraction Measurements of sub-ns Domain Dynamics in Ferroelectric Films

ABSTRACTWe used the Advanced Photon Source (APS) at Argonne National Laboratory to perform fast (ps range) time-resolved diffraction measurements of the dynamic characteristics in BaTiO3 films subjected to strong high-frequency electric fields. The time-dependent lattice response measured at frequencies between 6.5 MHz and 1.3 GHz revealed damped domain movements with attenuation time rapidly increasing with electric field frequency, v. We found that at frequencies higher than ν ∼ 600 MHz the domain motions in BaTiO3 films become heavily damped, information that may be important to future device operation. A minimum attenuation time, τ ∼ 330 ps, measured at ν = 1.3 GHz was limited by the time constant of the electrical circuit.

Measurement of the speed of X-rays.

X-ray pulses from the Advanced Photon Source at Argonne National Laboratory were used to measure the speed of X-rays in the energy range between 21 and 60 keV. An LiNbO(3)-based 0.58 GHz surface acoustic wave device served as a temporal analyzer in the stroboscopic time-resolved diffraction measurements. By synchronizing the surface acoustic wave excitation and periodic X-ray illumination of the LiNbO(3) crystal, the temporal modifications in the LiNbO(3) diffraction profiles could be followed and the time points of X-ray arrivals at the analyzer position for different analyzer to storage ring distances determined. The speed of the X-rays was determined as the ratio of measured spacings and corresponding delay time intervals. Within the experimental error bars, the obtained X-ray velocities converged to the tabulated constant for the speed of light in a vacuum.

特殊条件下の構造研究の新展開 高圧，応力過程での相転移の動的観察

Lattice instability due to plastic and elastic deformation under pressure induces many types of structure transformations, including changes of coordination number, cation ordering, electronic state such as charge disproportionation, charge transfer and electron density of state, and spin-lattice interaction. Nonhydrostaticity of compression brings metastable states or intermediate states, which are different from the thermo-dynamically stable phases, because they are temporary states in the dynamical process. Kinetic study of the pressure-induced transition is discussed in accordance with the in situ observation of time-resolved diffraction measurement. Besides the stress-strain relation, the crystallite size is an effective parameter of phase transition under pressure. Molecular dynamical calculation simulates the high-pressure phase transition.

Time Resolved Diffraction Measurements with an Imaging Plate at High Pressure and Temperature.

New developments of the imaging plate diffraction system at beamline X17B1 of the NSLS at Brookhaven National Laboratory for high pressure studies are reported here. Time resolved diffraction patterns can be recorded on an imaging plate by translating the plate in this system. This system was used to observe the olivine-spinel phase transformation in fayalite. The result demonstrates that the phase transformation relaxes stress stored in the sample. Some diffraction peaks of spinel phase, e. g. (400) and (440), were observed to appear prior to the others.

Powder diffraction for solid state reaction studies

A position sensitive detecting system for time resolved diffraction measurement is described. Investigation of the thermal decomposition of lime shows that quantitative results can be obtained studying solid state chemical reactions whose duration lasts about one second.

Charge integrating type position-sensitive proportional chamber for time-resolved measurements using intense X-ray sources

A position-sensitive detecting system for time-resolved diffraction measurements with very intensive X-ray sources has been developed. It consists of a charge integrating type gas-filled detector, multichannel analog multiplexers, a signal processor and a memory (120 ch.×128 phases×24 bits). The detector is 120 mm long in effective length by 10 mm×10 mm in cross section with a single anode of 20 μm diameter. One of the cathode planes consists of 120 cathode strips with a pitch of 1 mm. The spatial resolution is equal to the pitch under a certain detector current limit. The gas gain is adjustable to an appropriate value according to the X-ray intensity range of interest. For experiments with 8 keV X-ray sources, maximum absorption rates of 9×10 7 photons/s·mm with low applied voltage and minimum absorption rates of about 3 photons/s·mm with high applied voltage can be achieved. This system was applied to a time-resolved X-ray diffraction study on frog muscle using a synchrotron radiation source at the Photon Factory and we could collect diffraction patterns with a time resolution of 10 ms and only 10 stimulations.