Sensitivity of time‐resolved diffraction data to changes in internuclear distances and atomic positions

Jeong Haeyun,Ki Hosung,Kim Jong Goo,Kim Jungmin,Lee Yunbeom,Ihee Hyotcherl 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.3

Time-resolved x-ray liquidography (TRXL) is a powerful technique to study molecular structural dynamics in the solution phase. Typically, a TRXL experiment is conducted during limited beamtime at a beamline of a synchrotron or an x-ray free-electron laser, demanding a proper design and careful planning. In this regard, the optimal q range needs to be determined to find the optimal x-ray energy and sample-to-detector distance. For such purpose, here, we present effective ways to quantify the sensitivity of the TRXL data as a function of q to various factors such as the atomic positions, internuclear distances, solvent cage, and bulk solvent. The developed approaches are also applicable to other types of time-resolved diffraction, such as ultrafast electron diffraction.

Spatiotemporal Kinetics in Solution Studied by Time-Resolved X-Ray Liquidography (Solution Scattering)

Kim, Tae Kyu,Lee, Jae Hyuk,Wulff, Michael,Kong, Qingyu,Ihee, Hyotcherl WILEY-VCH Verlag 2009 CHEMPHYSCHEM -WEINHEIM- Vol.10 No.12

<P>Information about temporally varying molecular structure during chemical processes is crucial for understanding the mechanism and function of a chemical reaction. Using ultrashort optical pulses to trigger a reaction in solution and using time-resolved X-ray diffraction (scattering) to interrogate the structural changes in the molecules, time-resolved X-ray liquidography (TRXL) is a direct tool for probing structural dynamics for chemical reactions in solution. TRXL can provide direct structural information that is difficult to extract from ultrafast optical spectroscopy, such as the time dependence of bond lengths and angles of all molecular species including short-lived intermediates over a wide range of times, from picoseconds to milliseconds. TRXL elegantly complements ultrafast optical spectroscopy because the diffraction signals are sensitive to all chemical species simultaneously and the diffraction signal from each chemical species can be quantitatively calculated from its three-dimensional atomic coordinates and compared with experimental TRXL data. Since X-rays scatter from all the atoms in the solution sample, solutes as well as the solvent, the analysis of TRXL data can provide the temporal behavior of the solvent as well as the structural progression of all the solute molecules in all the reaction pathways, thus providing a global picture of the reactions and accurate branching ratios between multiple reaction pathways. The arrangement of the solvent around the solute molecule can also be extracted. This review summarizes recent developments in TRXL, including technical innovations in synchrotron beamlines and theoretical analysis of TRXL data, as well as several examples from simple molecules to an organometallic complex, nanoparticles, and proteins in solution. Future potential applications of TRXL in femtosecond studies and biologically relevant molecules are also briefly mentioned.</P> <B>Graphic Abstract</B> <P>Time and motion: Time-resolved X-ray liquidography (see picture) can directly probe the structural dynamics and spatiotemporal kinetics of the liquid phase with unprecedented spatial and temporal resolution. Recent developments in this method, including technical innovations, theoretical analysis, and several examples ranging from simple molecules to protein solutions, are reviewed. <img src='wiley_img/14394235-2009-10-12-CPHC200900154-content.gif' alt='wiley_img/14394235-2009-10-12-CPHC200900154-content'> </P>

Impact of rough silicon buffer layer on electronic quality of GaAs grown on Si substrate

B. Azeza,M. Ezzedini,Z. Zaaboub,R. M’ghaieth,L. Sfaxi,F. Hassen,H. Maaref 한국물리학회 2012 Current Applied Physics Vol.12 No.5

The electronic and the structural properties of n-GaAs layers grown on rough surface of silicon substrate by molecular beam epitaxy (MBE) has been investigated by photoluminescence (PL), time resolved photoluminescence (TRPL) and high resolution X-ray diffraction (HRXRD). The relationship between electronic and structural properties of the n-GaAs layer was checked, showing that the defect density is a strong cause for trapping the minority carriers. The impact of introducing intermediate rough silicon layer between silicon substrate and n-GaAs layer on the electronic properties was observed, showing that the structure grown on rough Si involves higher lifetime than those developed on flat silicon substrate. Such structure could be used for economic solar cells fabrication. The electronic and the structural properties of n-GaAs layers grown on rough surface of silicon substrate by molecular beam epitaxy (MBE) has been investigated by photoluminescence (PL), time resolved photoluminescence (TRPL) and high resolution X-ray diffraction (HRXRD). The relationship between electronic and structural properties of the n-GaAs layer was checked, showing that the defect density is a strong cause for trapping the minority carriers. The impact of introducing intermediate rough silicon layer between silicon substrate and n-GaAs layer on the electronic properties was observed, showing that the structure grown on rough Si involves higher lifetime than those developed on flat silicon substrate. Such structure could be used for economic solar cells fabrication.

Ultrafast Electron Diffraction Technology for Exploring Dynamics of Molecules

Kyu Ha Jang,Key Young Oang,In-Hyung Baek,Sadiq Setiniyaz,Ki-TaeLee,Young Uk Jeong,Hyunwoo Kim 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.4

With the recent successful development of X-ray free electron lasers (X-FELs), it became possible to explore sub-nano structure dynamics of materials with 100-fs temporal accuracy. Ultrafast electron diffraction (UED) can achieve similar performance at a much lower cost and on a smaller scale by using ultrashort and low-energy electron beams. The UEDs are suitable for studying thin films, surfaces, and gas samples that are difficult to study with the X-FELs. Starting from non-relativistic UEDs using low-energy electron beams of less than 100 keV, it led to the development of relativistic UEDs using a-few-MeV electron beams. These efforts have contributed to the identification of the unexplored mechanism of matter by observing the dynamics of atoms with higher temporal accuracy. Electron beam is easier to handle than X-rays, and various technologies are being developed to improve the performance of UED. We review UEDs historically based on the development of core technologies. And application researches with the UEDs will be outlined in this paper.

Solid Phase Characterization and Groundwater Solubility of Synthetic Sklodowskite

Wansik Cha,Junghwan Park,Hye Ran Noh,Hye-Ryun Cho 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

The disposal of spent nuclear fuel (SNF) in a deep geological repository (DGR) is a widely accepted strategy for the long-term sequestration of radiotoxic SNF. Ensuring the safety of a DGR requires the prediction of various reactions and migration behaviors of radionuclides (RNs) present in SNF within its geochemical surroundings. Understanding the dissolution behaviors of mineral phases harboring these RNs is crucial, as the levels of RNs in groundwater are basically linked to the solubility of these solid phases. Accurate measurements of solubility demand the use of welldefined solid materials characterized by chemical compositions and structures. Herein, we attempted the synthesis of sklodowskite, a magnesium-uranyl (U(VI))-silicate, employing a twostep hydrothermal synthetic approach documented previously. Subsequently, we subjected this synthesized sklodowskite to various analytical techniques, including powder X-ray diffraction (pXRD), scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX), and vibrational spectroscopies (FTIR and Raman). Based on our findings, we confidently identify the obtained mineral phase as sklodowskite (Mg[UO2SiO3OH]2·5H2O). This identification is primarily based on the similarity between its pXRD pattern and the reference XRD pattern of sklodowskite. Furthermore, the measured infrared and Raman spectra show the vibrational modes of UO2 2+ and SiO4 4- ions, particularly within the 700~1,100 cm-1 region, which support that the synthetic mineral has a characteristic layered uranyl-silicate structure of crystalline sklodowskite. Finally, we utilized synthetic minerals to estimate its solubility up to about three months in a model groundwater, where the dissolved species composition is analogous to that of granitic groundwater from the KAERI Underground Research Tunnel. In this presentation, we will present in detail the results of spectroscopic characterizations and the methodology employed to assess the solubility of the U(VI)-silicate solid phase.

X선의 초고속 결정구조 측정법

구영덕(Y.D.Koo),김영철(Y.C.Kim),오창섭(C.S.Oh) 한국에너지학회 2014 에너지공학 Vol.23 No.3