The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Yongkeun Park - One of the best experts on this subject based on the ideXlab platform.
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low coherent optical Diffraction Tomography by angle scanning illumination conference presentation
Quantitative Phase Imaging V, 2019Co-Authors: Kyeoreh Lee, Seungwoo Shin, Zahid Yaqoob, Yongkeun ParkAbstract:In coherent imaging systems, parasitic fringes and concentric patterns could commonly be found due to the unwanted multiple reflections [1]. One fundamental solution for the coherent noise is to use a temporally incoherent light source. However, maintaining the full-field interference fringe contrast using temporally incoherent light is not straightforward for interferometric imaging techniques such as quantitative phase imaging (QPI). Fortunately, several brilliant incoherent QPI techniques have been realized for wide-field imaging mainly through the common-path interferometer geometries [2-4]. However, it has been more difficult to implement incoherent-light-based optical Diffraction Tomography (ODT) due to the additional angle-scanning illumination unit that induces severe decoherence over the camera field-of-view [5]. Here, we suggest a temporally low-coherence optical Diffraction Tomography by angle-scanning broadband illumination based on general Mach-Zehnder interferometric geometry. We have designed an angle-scanning unit composed of two digital micromirror devices (DMDs) to maintain interference fringe contrast across the whole field of view during the angle-scanning sequence. Further, we have developed the theoretical framework for ODT reconstruction using incoherent light. In the light of our recent developments, we will discuss the theoretical and practical constraints, and suggest the best degree of incoherency for incoherent ODT. We will also demonstrate the incoherent optical Diffraction Tomography of plastic microspheres, human blood cells and rat pheochromocytoma cells. References 1. I. Choi, K. Lee, and Y. Park, "Compensation of aberration in quantitative phase imaging using lateral shifting and spiral phase integration," Opt. Express 25, 30771-30779 (2017). 2. Z. Wang, L. Millet, M. Mir, H. Ding, S. Unarunotai, J. Rogers, M. U. Gillette, and G. Popescu, "Spatial light interference microscopy (SLIM)," Opt. Express 19, 1016-1026 (2011). 3. B. Bhaduri, H. Pham, M. Mir, and G. Popescu, "Diffraction phase microscopy with white light," Opt. Lett. 37, 1094-1096 (2012). 4. Y. Baek, K. Lee, J. Yoon, K. Kim, and Y. Park, "White-light quantitative phase imaging unit," Opt. Express 24, 9308-9315 (2016). 5. M. Rinehart, Y. Zhu, and A. Wax, "Quantitative phase spectroscopy," Biomed. Opt. Express 3, 958-965 (2012).
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low coherent optical Diffraction Tomography by angle scanning illumination
Journal of Biophotonics, 2019Co-Authors: Seungwoo Shin, Kyeoreh Lee, Zahid Yaqoob, Yongkeun ParkAbstract:Temporally low-coherent optical Diffraction Tomography (ODT) is proposed and demonstrated based on angle-scanning Mach-Zehnder interferometry. Using a digital micromirror device based on diffractive tilting, the full-field interference of incoherent light is successfully maintained during every angle-scanning sequences. Further, current ODT reconstruction principles for temporally incoherent illuminations are thoroughly reviewed and developed. Several limitations of incoherent illumination are also discussed, such as the nondispersive assumption, optical sectioning capacity and illumination angle limitation. Using the proposed setup and reconstruction algorithms, low-coherent ODT imaging of plastic microspheres, human red blood cells and rat pheochromocytoma cells is experimentally demonstrated.
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super resolution three dimensional fluorescence and optical Diffraction Tomography of live cells using structured illumination generated by a digital micromirror device
Scientific Reports, 2018Co-Authors: Seungwoo Shin, Kyoohyun Kim, Doyeon Kim, Yongkeun ParkAbstract:We present a multimodal approach for measuring the three-dimensional (3D) refractive index (RI) and fluorescence distributions of live cells by combining optical Diffraction Tomography (ODT) and 3D structured illumination microscopy (SIM). A digital micromirror device is utilized to generate structured illumination patterns for both ODT and SIM, which enables fast and stable measurements. To verify its feasibility and applicability, the proposed method is used to measure the 3D RI distribution and 3D fluorescence image of various samples, including a cluster of fluorescent beads, and the time-lapse 3D RI dynamics of fluorescent beads inside a HeLa cell, from which the trajectory of the beads in the HeLa cell is analyzed using spatiotemporal correlations.
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label free high resolution 3 d imaging of gold nanoparticles inside live cells using optical Diffraction Tomography
Methods, 2017Co-Authors: Doyeon Kim, Kyoohyun Kim, Sangyun Lee, Changi Pack, Jiho Park, Yongkeun ParkAbstract:Delivery of gold nanoparticles (GNPs) into live cells has high potentials, ranging from molecular-specific imaging, photodiagnostics, to photothermal therapy. However, studying the long-term dynamics of cells with GNPs using conventional fluorescence techniques suffers from phototoxicity and photobleaching. Here, we present a method for 3-D imaging of GNPs inside live cells exploiting refractive index (RI) as imaging contrast. Employing optical Diffraction Tomography, 3-D RI tomograms of live cells with GNPs are precisely measured for an extended period with sub-micrometer resolution. The locations and contents of GNPs in live cells are precisely addressed and quantified due to their distinctly high RI values, which was validated by confocal fluorescence imaging of fluorescent dye conjugated GNPs. In addition, we perform quantitative imaging analysis including the segmentations of GNPs in the cytosol, the volume distributions of aggregated GNPs, and the temporal evolution of GNPs contents in HeLa and 4T1 cells.
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time multiplexed structured illumination using a dmd for optical Diffraction Tomography
Optics Letters, 2017Co-Authors: Seungwoo Shin, Yongkeun ParkAbstract:We present a time-multiplexing structured illumination control technique for optical Diffraction Tomography (ODT). Instead of tilting the angle of illumination, time-multiplexed sinusoidal illumination is exploited using a digital micromirror device (DMD). The present method effectively eliminates unwanted diffracted beams from binary DMD patterns, which deteriorates the image quality of the ODT in the previous binary Lee hologram method. We experimentally show the feasibility and advantage of the present method by reconstructing three-dimensional refractive index distributions of various samples and comparing with a conventional Lee hologram method.
Enrico Mugnaioli - One of the best experts on this subject based on the ideXlab platform.
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crystal structures of two important pharmaceuticals solved by 3d precession electron Diffraction Tomography
Organic Process Research & Development, 2018Co-Authors: Partha P Das, Mauro Gemmi, Athanassios S. Galanis, Stavros Nicolopoulos, Enrico Mugnaioli, Camilla Tossi, Gheorghe Borodi, Mihaela PopAbstract:The crystal structures of two important marketed pharmaceuticals, namely, ramelteon (RAM) and tolvaptan (TOL), were determined for the first time using 3D precession electron Diffraction Tomography (PEDT) on 500 nm-sized crystals. The results were compared with the same structures determined by single-crystal X-ray Diffraction on subsequently grown 50–200 μm single crystals, indicating a good match of molecular conformation, crystal packing, and unit cell parameters. The X-ray crystal structures were used to validate the developed workflow of data acquisition and structure solution with electron Diffraction. This study highlights that 3D PEDT alone is able to provide accurate crystal structures from pharmaceutical nanocrystals that will suffice for most practical applications when no larger crystals can be grown.
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ab initio structure determination of cu2 xte plasmonic nanocrystals by precession assisted electron Diffraction Tomography and haadf stem imaging
Inorganic Chemistry, 2018Co-Authors: Enrico Mugnaioli, Mauro Gemmi, Jeremy David, Giovanni Bertoni, Roberto Gaspari, Luca De Trizio, Liberato MannaAbstract:We investigated pseudo-cubic Cu2–xTe nanosheets using electron Diffraction Tomography and high-resolution HAADF-STEM imaging. The structure of this metastable nanomaterial, which has a strong local...
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Crystal Structures of Two Important Pharmaceuticals Solved by 3D Precession Electron Diffraction Tomography
2018Co-Authors: Partha P. Das, Mauro Gemmi, Stavros Nicolopoulos, Enrico Mugnaioli, Camilla Tossi, Athanasios Galanis, Gheorghe Borodi, Mihaela M. PopAbstract:The crystal structures of two important marketed pharmaceuticals, namely, ramelteon (RAM) and tolvaptan (TOL), were determined for the first time using 3D precession electron Diffraction Tomography (PEDT) on 500 nm-sized crystals. The results were compared with the same structures determined by single-crystal X-ray Diffraction on subsequently grown 50–200 μm single crystals, indicating a good match of molecular conformation, crystal packing, and unit cell parameters. The X-ray crystal structures were used to validate the developed workflow of data acquisition and structure solution with electron Diffraction. This study highlights that 3D PEDT alone is able to provide accurate crystal structures from pharmaceutical nanocrystals that will suffice for most practical applications when no larger crystals can be grown
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ultrafast electron Diffraction Tomography for structure determination of the new zeolite itq 58
Journal of the American Chemical Society, 2016Co-Authors: Jorge Simancas, Mauro Gemmi, Stavros Nicolopoulos, Partha P Das, Raquel Simancas, Pablo J Bereciartua, Jose L Jorda, Fernando Rey, Avelino Corma, Enrico MugnaioliAbstract:In this work a new ultrafast data collection strategy for electron Diffraction Tomography is presented that allows reducing data acquisition time by one order of magnitude. This methodology minimizes the radiation damage of beam-sensitive materials, such as microporous materials. This method, combined with the precession of the electron beam, provides high quality data enabling the determination of very complex structures. Most importantly, the implementation of this new electron Diffraction methodology is easily affordable in any modern electron microscope. As a proof of concept, we have solved a new highly complex zeolitic structure named ITQ-58, with a very low symmetry (triclinic) and a large unit cell volume (1874.6 A3), containing 16 silicon and 32 oxygen atoms in its asymmetric unit, which would be very difficult to solve with the state of the art techniques.
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ba6p12n17o9br3 a column type phosphate structure solved from single nanocrystal data obtained by automated electron Diffraction Tomography
European Journal of Inorganic Chemistry, 2012Co-Authors: Enrico Mugnaioli, Ute Kolb, Stefan J Sedlmaier, Oliver Oeckler, Wolfgang SchnickAbstract:Oxonitridophosphate Ba6P12N17O9Br3 was synthesized by heating a multicomponent mixture of BaBr2, BaS, phosphoryl triamide and thiophosphoryl triamide in an evacuated and sealed silica-glass ampoule to 750 °C. Ba6P12N17O9Br3 was obtained as the main product as a nanocrystalline powder. The crystal structure was determined ab initio on the basis of electron Diffraction data acquired from a single needle-shaped nanocrystal by automated Diffraction Tomography. Ba6P12N17O9Br3 crystallizes in the hexagonal space group P63/m (no. 176) with unit cell parameters a = 14.654(19), c = 8.255(9) A and Z = 2. Its structure includes triangular, column-shaped anions of ∞1{(P12N17O9)9–}, which are built from vertex-sharing P(O,N)4 tetrahedra with 3-rings and three-coordinate nitrogen atoms. The 1D anions are separated by Ba2+ and Br– ions, which are arranged in channels parallel to the phosphate anions along [001]. The Ba2+ ions are eight- and nine-coordinated by Br– and O/N atoms, respectively.
Kyoohyun Kim - One of the best experts on this subject based on the ideXlab platform.
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quantitative imaging of caenorhabditis elegans dauer larvae during cryptobiotic transition using optical Diffraction Tomography
bioRxiv, 2021Co-Authors: Kyoohyun Kim, Vamshidhar Gade, Teymuras V Kurzchalia, Jochen GuckAbstract:Upon starvation or overcrowding, the nematode Caenorhabditis elegans enters diapause by forming a dauer larva. This larva can further transit into an anhydrobiotic state and survive harsh desiccation. We previously identified the genetic and biochemical pathways essential for survival -- but without an accompanying physical model, the mechanistic understanding of this amazing phenomenon will remain inadequate. Neither microscopic investigation of structural changes upon entry into anhydrobiosis nor the most basic quantitative characterization of material properties of living desiccated larvae, however, have been feasible, due to lack of appropriate techniques. Here, we employed optical Diffraction Tomography (ODT) to quantitatively assess the internal mass density distribution of living larvae in the reproductive and diapause stages. More importantly, ODT allowed for the first time physical analysis of desiccated dauer larvae: their mass density was significantly increased in the anhydrobiotic state. We also applied ODT on different mutants that are sensitive to desiccation. Remarkably, one of them displayed structural abnormalities in the anhydrobiotic stage that could not be observed either by conventional light or electron microscopy. Our advance opens a door to quantitatively assessing fine differences in material properties and structure necessary to fully understanding an organism on the verge of life and death.
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combined fluorescence optical Diffraction Tomography and brillouin microscopy
bioRxiv, 2020Co-Authors: Raimund Schlusler, Kyoohyun Kim, Martin Notzel, Anna Taubenberger, Shada Abuhattum Hofemeier, Timon Beck, Paul Muller, Shovamayee Maharana, Gheorghe CojocAbstract:Abstract Quantitative measurements of physical parameters become increasingly important for understanding biological processes. Brillouin microscopy (BM) has recently emerged as one technique providing the 3D distribution of viscoelastic properties inside biological samples — so far relying on the implicit assumption that refractive index (RI) and density can be neglected. Here, we present a novel method (FOB microscopy) combining BM with optical Diffraction Tomography and epi-fluorescence imaging for explicitly measuring the Brillouin shift, RI and absolute density with molecular specificity. We show that neglecting the RI and density might lead to erroneous conclusions. Investigating the cell nucleus, we find that it has lower density but higher longitudinal modulus. Thus, the longitudinal modulus is not merely sensitive to the water content of the sample — a postulate vividly discussed in the field. We demonstrate the further utility of FOB on various biological systems including adipocytes and intracellular membraneless compartments. FOB microscopy can provide unexpected scientific discoveries and shed quantitative light on processes such as phase separation and transition inside living cells.
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super resolution three dimensional fluorescence and optical Diffraction Tomography of live cells using structured illumination generated by a digital micromirror device
Scientific Reports, 2018Co-Authors: Seungwoo Shin, Kyoohyun Kim, Doyeon Kim, Yongkeun ParkAbstract:We present a multimodal approach for measuring the three-dimensional (3D) refractive index (RI) and fluorescence distributions of live cells by combining optical Diffraction Tomography (ODT) and 3D structured illumination microscopy (SIM). A digital micromirror device is utilized to generate structured illumination patterns for both ODT and SIM, which enables fast and stable measurements. To verify its feasibility and applicability, the proposed method is used to measure the 3D RI distribution and 3D fluorescence image of various samples, including a cluster of fluorescent beads, and the time-lapse 3D RI dynamics of fluorescent beads inside a HeLa cell, from which the trajectory of the beads in the HeLa cell is analyzed using spatiotemporal correlations.
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label free high resolution 3 d imaging of gold nanoparticles inside live cells using optical Diffraction Tomography
Methods, 2017Co-Authors: Doyeon Kim, Kyoohyun Kim, Sangyun Lee, Changi Pack, Jiho Park, Yongkeun ParkAbstract:Delivery of gold nanoparticles (GNPs) into live cells has high potentials, ranging from molecular-specific imaging, photodiagnostics, to photothermal therapy. However, studying the long-term dynamics of cells with GNPs using conventional fluorescence techniques suffers from phototoxicity and photobleaching. Here, we present a method for 3-D imaging of GNPs inside live cells exploiting refractive index (RI) as imaging contrast. Employing optical Diffraction Tomography, 3-D RI tomograms of live cells with GNPs are precisely measured for an extended period with sub-micrometer resolution. The locations and contents of GNPs in live cells are precisely addressed and quantified due to their distinctly high RI values, which was validated by confocal fluorescence imaging of fluorescent dye conjugated GNPs. In addition, we perform quantitative imaging analysis including the segmentations of GNPs in the cytosol, the volume distributions of aggregated GNPs, and the temporal evolution of GNPs contents in HeLa and 4T1 cells.
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label free high resolution 3 d imaging of gold nanoparticles inside live cells using optical Diffraction Tomography
bioRxiv, 2016Co-Authors: Doyeon Kim, Kyoohyun Kim, Sangyun Lee, Jiho Park, Yongkeun ParkAbstract:Delivery of gold nanoparticles (GNPs) into live cells has high potentials, ranging from molecular-specific imaging, photodiagnostics, to photothermal therapy. However, studying the long-term dynamics of cells with GNPs using conventional fluorescence techniques suffer from phototoxicity and photobeaching. Here, we present a method for 3-D imaging of GNPs inside live cells exploiting refractive index (RI) as imaging contrast. Employing optical Diffraction Tomography, 3-D RI tomograms of live cells with GNPs are precisely measured for an extended period of time with sub-micrometre resolution. The locations and contents of GNPs in live cells are precisely addressed and quantified due to their distinctly high RI values, which was validated by confocal fluorescence imaging of fluorescent dye conjugated GNPs. We present segmentations of GNPs from cytosols and perform quantitative analysis of the volume distribution of aggregated GNPs as well as the temporal evolution of GNPs contents in HeLa and 4T1 cells.
Seungwoo Shin - One of the best experts on this subject based on the ideXlab platform.
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low coherent optical Diffraction Tomography by angle scanning illumination conference presentation
Quantitative Phase Imaging V, 2019Co-Authors: Kyeoreh Lee, Seungwoo Shin, Zahid Yaqoob, Yongkeun ParkAbstract:In coherent imaging systems, parasitic fringes and concentric patterns could commonly be found due to the unwanted multiple reflections [1]. One fundamental solution for the coherent noise is to use a temporally incoherent light source. However, maintaining the full-field interference fringe contrast using temporally incoherent light is not straightforward for interferometric imaging techniques such as quantitative phase imaging (QPI). Fortunately, several brilliant incoherent QPI techniques have been realized for wide-field imaging mainly through the common-path interferometer geometries [2-4]. However, it has been more difficult to implement incoherent-light-based optical Diffraction Tomography (ODT) due to the additional angle-scanning illumination unit that induces severe decoherence over the camera field-of-view [5]. Here, we suggest a temporally low-coherence optical Diffraction Tomography by angle-scanning broadband illumination based on general Mach-Zehnder interferometric geometry. We have designed an angle-scanning unit composed of two digital micromirror devices (DMDs) to maintain interference fringe contrast across the whole field of view during the angle-scanning sequence. Further, we have developed the theoretical framework for ODT reconstruction using incoherent light. In the light of our recent developments, we will discuss the theoretical and practical constraints, and suggest the best degree of incoherency for incoherent ODT. We will also demonstrate the incoherent optical Diffraction Tomography of plastic microspheres, human blood cells and rat pheochromocytoma cells. References 1. I. Choi, K. Lee, and Y. Park, "Compensation of aberration in quantitative phase imaging using lateral shifting and spiral phase integration," Opt. Express 25, 30771-30779 (2017). 2. Z. Wang, L. Millet, M. Mir, H. Ding, S. Unarunotai, J. Rogers, M. U. Gillette, and G. Popescu, "Spatial light interference microscopy (SLIM)," Opt. Express 19, 1016-1026 (2011). 3. B. Bhaduri, H. Pham, M. Mir, and G. Popescu, "Diffraction phase microscopy with white light," Opt. Lett. 37, 1094-1096 (2012). 4. Y. Baek, K. Lee, J. Yoon, K. Kim, and Y. Park, "White-light quantitative phase imaging unit," Opt. Express 24, 9308-9315 (2016). 5. M. Rinehart, Y. Zhu, and A. Wax, "Quantitative phase spectroscopy," Biomed. Opt. Express 3, 958-965 (2012).
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low coherent optical Diffraction Tomography by angle scanning illumination
Journal of Biophotonics, 2019Co-Authors: Seungwoo Shin, Kyeoreh Lee, Zahid Yaqoob, Yongkeun ParkAbstract:Temporally low-coherent optical Diffraction Tomography (ODT) is proposed and demonstrated based on angle-scanning Mach-Zehnder interferometry. Using a digital micromirror device based on diffractive tilting, the full-field interference of incoherent light is successfully maintained during every angle-scanning sequences. Further, current ODT reconstruction principles for temporally incoherent illuminations are thoroughly reviewed and developed. Several limitations of incoherent illumination are also discussed, such as the nondispersive assumption, optical sectioning capacity and illumination angle limitation. Using the proposed setup and reconstruction algorithms, low-coherent ODT imaging of plastic microspheres, human red blood cells and rat pheochromocytoma cells is experimentally demonstrated.
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super resolution three dimensional fluorescence and optical Diffraction Tomography of live cells using structured illumination generated by a digital micromirror device
Scientific Reports, 2018Co-Authors: Seungwoo Shin, Kyoohyun Kim, Doyeon Kim, Yongkeun ParkAbstract:We present a multimodal approach for measuring the three-dimensional (3D) refractive index (RI) and fluorescence distributions of live cells by combining optical Diffraction Tomography (ODT) and 3D structured illumination microscopy (SIM). A digital micromirror device is utilized to generate structured illumination patterns for both ODT and SIM, which enables fast and stable measurements. To verify its feasibility and applicability, the proposed method is used to measure the 3D RI distribution and 3D fluorescence image of various samples, including a cluster of fluorescent beads, and the time-lapse 3D RI dynamics of fluorescent beads inside a HeLa cell, from which the trajectory of the beads in the HeLa cell is analyzed using spatiotemporal correlations.
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time multiplexed structured illumination using a dmd for optical Diffraction Tomography
Optics Letters, 2017Co-Authors: Seungwoo Shin, Yongkeun ParkAbstract:We present a time-multiplexing structured illumination control technique for optical Diffraction Tomography (ODT). Instead of tilting the angle of illumination, time-multiplexed sinusoidal illumination is exploited using a digital micromirror device (DMD). The present method effectively eliminates unwanted diffracted beams from binary DMD patterns, which deteriorates the image quality of the ODT in the previous binary Lee hologram method. We experimentally show the feasibility and advantage of the present method by reconstructing three-dimensional refractive index distributions of various samples and comparing with a conventional Lee hologram method.
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optical Diffraction Tomography techniques for the study of cell pathophysiology
Journal of Biomedical Photonics & Engineering, 2016Co-Authors: Jonghee Yoon, Seungwoo Shin, Sua Yang, Yongkeun ParkAbstract:Three-dimensional imaging of biological cells is crucial for the investigation of cell biology, providing valuable information to reveal the mechanisms behind pathophysiology of cells and tissues. Recent advances in optical Diffraction Tomography (ODT) have demonstrated the potential for the study of various cells with its unique advantages of quantitative and label-free imaging capability. To provide insight on this rapidly growing field of research and to discuss its applications in biology and medicine, we present the summary of the ODT principle and highlight recent studies utilizing ODT with the emphasis on the applications to the pathophysiology of cells.
Ute Kolb - One of the best experts on this subject based on the ideXlab platform.
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a new microporous 12 ring zincosilicate thk 2 with many terminal silanols characterized by automated electron Diffraction Tomography
Dalton Transactions, 2020Co-Authors: Ute Kolb, Yasuhiro Sakamoto, Haishuang Zhao, Hermann Gies, Katsutoshi Yamamoto, Takuji IkedaAbstract:A newly synthesized microporous zincosilicate THK-2 (estimated structural composition: |(H2O)6.7(C6H13N)0.9|[Li0.5Zn3.1Si32O62.7(OH)9.3]) was characterized by single-crystal electron Diffraction using the automated electron Diffraction Tomography (ADT) approach in combination with powder X-ray Diffraction. The lattice constants and space group of as-synthesized THK-2 were a = 2.50377(7) nm, b = 1.43866(4) nm, c = 0.505369(8) nm, and Pccn (no. 56) with orthorhombic symmetry. Because the crystal lattice was almost identical to a hexagonal lattice (), the first several peaks in its powder X-ray Diffraction data severely overlapped, which suppressed the structural information to decide the framework topology. In order to overcome this intrinsic difficulty, the structure model of THK-2 was initially obtained by the direct method based on ADT data and refined by the Rietveld method. Its 3-dimensional framework structure was elucidated and it consisted of 4-, 5-, 6-rings of tetrahedral Si and Zn atoms and a one-dimensional straight channel with a 12-ring pore opening. Zn atoms were incorporated into the framework as four-coordinated [ZnO4], although their distribution was confirmed to be disorderly. In the as-synthesized THK-2, the site occupancy of Zn was as low as 0.39; that is, more than 60% of the Zn sites were vacant. Hexamethyleneimine and water molecules were accommodated in the straight channel in a disordered manner. The material was stable upon calcination, and the BET specific surface area and micropore volume of calcined THK-2 were 240.6 m2 g−1 and 0.12 ml g−1, respectively.
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ba6p12n17o9br3 a column type phosphate structure solved from single nanocrystal data obtained by automated electron Diffraction Tomography
European Journal of Inorganic Chemistry, 2012Co-Authors: Enrico Mugnaioli, Ute Kolb, Stefan J Sedlmaier, Oliver Oeckler, Wolfgang SchnickAbstract:Oxonitridophosphate Ba6P12N17O9Br3 was synthesized by heating a multicomponent mixture of BaBr2, BaS, phosphoryl triamide and thiophosphoryl triamide in an evacuated and sealed silica-glass ampoule to 750 °C. Ba6P12N17O9Br3 was obtained as the main product as a nanocrystalline powder. The crystal structure was determined ab initio on the basis of electron Diffraction data acquired from a single needle-shaped nanocrystal by automated Diffraction Tomography. Ba6P12N17O9Br3 crystallizes in the hexagonal space group P63/m (no. 176) with unit cell parameters a = 14.654(19), c = 8.255(9) A and Z = 2. Its structure includes triangular, column-shaped anions of ∞1{(P12N17O9)9–}, which are built from vertex-sharing P(O,N)4 tetrahedra with 3-rings and three-coordinate nitrogen atoms. The 1D anions are separated by Ba2+ and Br– ions, which are arranged in channels parallel to the phosphate anions along [001]. The Ba2+ ions are eight- and nine-coordinated by Br– and O/N atoms, respectively.
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srp3n5o a highly condensed layer phosphate structure solved from a nanocrystal by automated electron Diffraction Tomography
Chemistry: A European Journal, 2011Co-Authors: Stefan J Sedlmaier, Enrico Mugnaioli, Ute Kolb, Oliver Oeckler, Wolfgang SchnickAbstract:The oxonitridophosphate SrP(3)N(5)O has been synthesized by heating a multicomponent reactant mixture that consisted of phosphoryl triamide OP(NH(2))(3), thiophosphoryl triamide SP(NH(2))(3), SrS, and NH(4)Cl enclosed in evacuated and sealed silica-glass ampoules up to 750 °C. The compound was obtained as nanocrystalline powder with needle-shaped crystallites. The crystal structure was solved ab initio on the basis of electron Diffraction data by means of automated electron Diffraction Tomography (ADT) and verified by Rietveld refinement with X-ray powder Diffraction data. SrP(3)N(5)O crystallizes in the orthorhombic space group Pnma (no. 62) with unit-cell data of a=18.331(2), b=8.086(1), c=13.851(1) A and Z=16. The compound is a highly condensed layer phosphate with a degree of condensation κ=½. The corrugated layers (∞)(2){(P(3)N(5)O)(2-)} consist of linked, triangular columns built up from P(O,N)(4) tetrahedra with 3-rings and triply binding nitrogen atoms. The Sr(2+) ions are located between the layers and exhibit six-, eight-, and ninefold coordination. FTIR and solid-state NMR spectra of SrP(3)N(5)O are discussed as well.
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automated electron Diffraction Tomography a new tool for nano crystal structure analysis
Crystal Research and Technology, 2011Co-Authors: Ute Kolb, Enrico Mugnaioli, Tatiana GorelikAbstract:Automated electron Diffraction Tomography (ADT) comprises an upcoming method for “ab intio” structure analysis of nano crystals. ADT allows fine sampling of the reciprocal space by sequential collection of electron Diffraction patterns while tilting a nano crystal in fixed tilt steps around an arbitrary axis. Electron Diffraction is collected in nano Diffraction mode (NED) with a semi-parallel beam with a diameter down to 50 nm. For crystal tracking micro-probe STEM imaging is used. Full automation of the acquisition procedure allowed optimisation of the electron dose distribution and therefore analysis of highly beam sensitive samples. Cell parameters, space group and reflection intensities can be determined directly within a reconstructed 3d Diffraction volume using a dedicated software package (ADT3D). Intensity data sets extracted from such a volume usually show a high coverage and significantly reduced dynamical effects due to “off-zone” acquisition. The use of this data for “ab initio” structure solution by direct methods implemented in standard programs for X-ray crystallography is demonstrated. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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ab initio structure solution from electron Diffraction data obtained by a combination of automated Diffraction Tomography and precession technique
Ultramicroscopy, 2009Co-Authors: Enrico Mugnaioli, Tatiana Gorelik, Ute KolbAbstract:Abstract Using a combination of our recently developed automated Diffraction Tomography (ADT) module with precession electron technique (PED), quasi-kinematical 3D Diffraction data sets of an inorganic salt (BaSO4) were collected. The lattice cell parameters and their orientation within the data sets were found automatically. The extracted intensities were used for “ab initio” structure analysis by direct methods. The data set covered almost the complete set of possible symmetrically equivalent reflections for an orthorhombic structure. The structure solution in one step delivered all heavy (Ba, S) as well as light atoms (O). Results of the structure solution using direct methods, charge flipping and maximum entropy algorithms as well as structure refinement for three different 3D electron Diffraction data sets were presented.