Akihiro Suzuki

Single-shot three-dimensional structure determination of nanocrystals with femtosecond X-ray free-electron laser pulses

Conventional three-dimensional (3D) structure determination methods require either multiple measurements at different sample orientations or a collection of serial sections through a sample. Here we report the experimental demonstration of single-shot 3D structure determination of an object; in this case, individual gold nanocrystals at ~5.5 nm resolution using ~10 fs X-ray free-electron laser pulses. Coherent diffraction patterns are collected from high-index-faceted nanocrystals, each struck by an X-ray free-electron laser pulse. Taking advantage of the symmetry of the nanocrystal and the curvature of the Ewald sphere, we reconstruct the 3D structure of each nanocrystal from a single-shot diffraction pattern. By averaging a sufficient number of identical nanocrystals, this method may be used to determine the 3D structure of nanocrystals at atomic resolution. As symmetry exists in many virus particles, this method may also be applied to 3D structure studies of such particles at nanometer resolution on femtosecond time scales.

Coherent diffraction imaging analysis of shape-controlled nanoparticles with focused hard X-ray free-electron laser pulses

We report the first demonstration of the coherent diffraction imaging analysis of nanoparticles using focused hard X-ray free-electron laser pulses, allowing us to analyze the size distribution of particles as well as the electron density projection of individual particles. We measured 1000 single-shot coherent X-ray diffraction patterns of shape-controlled Ag nanocubes and Au/Ag nanoboxes and estimated the edge length from the speckle size of the coherent diffraction patterns. We then reconstructed the two-dimensional electron density projection with sub-10 nm resolution from selected coherent diffraction patterns. This method enables the simultaneous analysis of the size distribution of synthesized nanoparticles and the structures of particles at nanoscale resolution to address correlations between individual structures of components and the statistical properties in heterogeneous systems such as nanoparticles and cells.

KOTOBUKI-1 apparatus for cryogenic coherent X-ray diffraction imaging

We have developed an experimental apparatus named KOTOBUKI-1 for use in coherent X-ray diffraction imaging experiments of frozen-hydrated non-crystalline particles at cryogenic temperature. For cryogenic specimen stage with small positional fluctuation for a long exposure time of more than several minutes, we here use a cryogenic pot cooled by the evaporation cooling effect for liquid nitrogen. In addition, a loading device is developed to bring specimens stored in liquid nitrogen to the specimen stage in vacuum. The apparatus allows diffraction data collection for frozen-hydrated specimens at 66 K with a positional fluctuation of less than 0.4 μm and provides an experimental environment to easily exchange specimens from liquid nitrogen storage to the specimen stage. The apparatus was developed and utilized in diffraction data collection of non-crystalline particles with dimensions of μm from material and biological sciences, such as metal colloid particles and chloroplast, at BL29XU of SPring-8. Recently, it has been applied for single-shot diffraction data collection of non-crystalline particles with dimensions of sub-μm using X-ray free electron laser at BL3 of SACLA.

Multiscale element mapping of buried structures by ptychographic x-ray diffraction microscopy using anomalous scattering

We propose an element mapping technique of nano-meso-microscale structures buried within large and/or thick objects by ptychographic x-ray diffraction microscopy using anomalous scattering. We performed quantitative imagings of both the electron density and Au element of Au/Ag nanoparticles at the pixel resolution of better than 10u2009nm in a field of view larger than 5u2009×u20095u2009μm2 by directly phasing ptychographic coherent diffraction patterns acquired at two x-ray energies below the Au L3 edge. This method provides us with multiscale structural and elemental information for understanding the element/property relationship linking nanoscale structures to macroscopic functional properties in material and biological systems.

High-resolution and high-sensitivity phase-contrast imaging by focused hard x-ray ptychography with a spatial filter

We demonstrate high-resolution and high-sensitivity x-ray phase-contrast imaging of a weakly scattering extended object by scanning coherent diffractive imaging, i.e., ptychography, using a focused x-ray beam with a spatial filter. We develop the x-ray illumination optics installed with the spatial filter to collect coherent diffraction patterns with a high signal-to-noise ratio. We quantitatively visualize the object with a slight phase shift (∼λ/320) at spatial resolution better than 17 nm in a field of view larger than ∼2×2μm2. The present coherent method has a marked potential for high-resolution and wide-field-of-view observation of weakly scattering objects such as biological soft tissues.

Automated calibration for micro hand using visual information

An automated calibration for micro-hand is proposed to obtain high quality micromanipulation system. The calibration is based on automatic focusing of micro-object and its position detection in the microscope frame using microscope images. The automatic focusing works well even in the tracking of moving target using chromatic aberration. The finger position can be detected automatically by integrating focusing and identification of the micro-hand finger wherever it is in the microscope view. These automated processes are implemented in the actual system. The experiment shows the system can attain around 2[/spl mu/m] in absolute positioning accuracy.

Automated micro handling

Biotechnologies demand high quality micro robotics including micromanipulation, micro machining, micro assembling, and other required micro operations. Most of them are done manually under microscope, and it might be an obstacle to increasing the efficiency of the operation. The automated micromanipulation (or automicromanipulation) system will be useful for reducing human tasks and improving the efficiency. We develop an auto-micromanipulation system including auto-calibration and auto-handling. Auto-calibration requires recognition of fingertip position in three-dimensional space. The fingertip position is detected by the combination of the one-dimensional search in depth using auto-focusing and the two-dimensional search in depth using auto-focusing and the two-dimensional search in the focused plane using the correlation matching. The color information processing is adopted for the auto-focusing. Using the calibrated micromanipulator, we achieved some micro tasks, picking up, rotating and so on. We developed an auto-micromanipulation system that can recognize and pick up a micro object automatically. The experimental results show the efficiency of our system.

Grain rotation and lattice deformation during photoinduced chemical reactions revealed by in situ X-ray nanodiffraction

In situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) have been used to investigate many physical science phenomena, ranging from phase transitions, chemical reactions and crystal growth to grain boundary dynamics. A major limitation of in situ XRD and TEM is a compromise that has to be made between spatial and temporal resolution. Here, we report the development of in situ X-ray nanodiffraction to measure high-resolution diffraction patterns from single grains with up to 5 ms temporal resolution. We observed, for the first time, grain rotation and lattice deformation in chemical reactions induced by X-ray photons: Br(-) + hv → Br + e(-) and e(-) + Ag(+) → Ag(0). The grain rotation and lattice deformation associated with the chemical reactions were quantified to be as fast as 3.25 rad s(-1) and as large as 0.5 Å, respectively. The ability to measure high-resolution diffraction patterns from individual grains with a temporal resolution of several milliseconds is expected to find broad applications in materials science, physics, chemistry andxa0nanoscience.

Dark-field X-ray ptychography

The dynamic range of X-ray detectors is a key factor limiting both the spatial resolution and sensitivity of X-ray ptychography as well as the coherent flux of incident X-rays. Here, we propose a method for high-resolution and high-sensitivity X-ray ptychography named dark-field X-ray ptychography, which compresses the dynamic range of intensities of diffraction patterns. In this method, a small reference object is aligned upstream of the sample. The scattered X-rays from the object work as a reference beam for in-line holography. Ptychographic diffraction patterns including the in-line hologram are collected, and then the image of the sample is reconstructed by an iterative phasing method. This method allows us to obscure the low-Q region of the diffraction patterns using a beamstop since the in-line hologram complements structural information in the low-Q region, resulting in the compression of the dynamic range of intensities of diffraction patterns. A numerical study shows that the dynamic range of intensities of diffraction patterns is decreased by about three orders of magnitude.

Efficient use of coherent X-rays in ptychography: Towards high-resolution and high-throughput observation of weak-phase objects

The efficient use of coherentX-rays is a crucial issue for ptychography at synchrotron facilities. We propose a method for optimizing the population of coherent modes for an optimal resolution. We show by a wave optical simulation that the intensity of a nearly diffraction-limited focusing X-ray beam can be described as an incoherent sum of a few orthogonal modes and that the first-mode flux significantly increases within a secondary source size by relaxing the requirement on the degree of coherence. We experimentally demonstrate it by means of multiple-mode ptychography with a synchrotron X-ray and achieve the high-resolution imaging of a weak-phase object. The present approach enables the high-resolution and high-throughput observation of weak-phase objects in materials science and biology.