The Experts below are selected from a list of 33258 Experts worldwide ranked by ideXlab platform
Peng Gao - One of the best experts on this subject based on the ideXlab platform.
-
picometer scale Atom Position analysis in annular bright field stem imaging
Ultramicroscopy, 2018Co-Authors: Peng Gao, Akihito Kumamoto, Ryo Ishikawa, Nathan R Lugg, Naoya Shibata, Yuichi IkuharaAbstract:Abstract We study the effects of specimen mistilt on the picometer-scale measurement of local structure by combing experiment and simulation in annular bright-field scanning transmission electron microscopy (ABF-STEM). A relative distance measurement method is proposed to separate the tilt effects from the scan noise and sample drift induced image distortion. We find that under a typical experimental condition a small specimen tilt (∼6 mrad) in 25 nm thick SrTiO3 along [001] causes 11.9 pm artificial displacement between O and Sr/TiO columns in ABF image, which is more than 3 times of scan noise and sample drift induced image distortion ∼3.2 pm, suggesting the tilt effect could be dominant for the quantitative analysis of ABF images. The artifact depends on the crystal mistilt angle, specimen thickness, defocus, convergence angle and uncorrected aberration. Our study provides useful insights into detecting and correcting tilt effects during both experiment operation and data analysis to extract the real structure information and avoid mis-interpretations of Atomic structure as well as the properties such as oxygen octahedral distortion/shift.
-
picometer scale Atom Position analysis in annular bright field stem imaging
arXiv: Materials Science, 2017Co-Authors: Peng Gao, Akihito Kumamoto, Ryo Ishikawa, Nathan R Lugg, Naoya Shibata, Yuichi IkuharaAbstract:We study the effects of specimen mistilt on the picometer-scale measurement of local structure by combing experiment and simulation in annular bright-field scanning transmission electron microscopy (ABF-STEM). A relative distance measurement method is proposed to separate the tilt effects from the scan noise and scan distortion. We find that under a typical experimental condition a small specimen tilt (~6 mrad) in 25 nm thick SrTiO3 along [001] causes 11.9 pm artificial displacement between O and Sr/TiO columns in ABF image, which is more than 3 times of scan noise and sample drift induced image distortion ~3.2 pm, suggesting the tilt effect could be dominant for the quantitative analysis of ABF images. The artifact depends the crystal mistilt angle, specimen thickness, defocus, convergence angle and uncorrected aberration. Our study provides useful insights into detecting and correcting tilt effects during both experiment operation and data analysis to extract the real structure information and avoid mis-interpretations of Atomic structure as well as the properties such as oxygen octahedral distortion/shift.
Yuichi Ikuhara - One of the best experts on this subject based on the ideXlab platform.
-
picometer scale Atom Position analysis in annular bright field stem imaging
Ultramicroscopy, 2018Co-Authors: Peng Gao, Akihito Kumamoto, Ryo Ishikawa, Nathan R Lugg, Naoya Shibata, Yuichi IkuharaAbstract:Abstract We study the effects of specimen mistilt on the picometer-scale measurement of local structure by combing experiment and simulation in annular bright-field scanning transmission electron microscopy (ABF-STEM). A relative distance measurement method is proposed to separate the tilt effects from the scan noise and sample drift induced image distortion. We find that under a typical experimental condition a small specimen tilt (∼6 mrad) in 25 nm thick SrTiO3 along [001] causes 11.9 pm artificial displacement between O and Sr/TiO columns in ABF image, which is more than 3 times of scan noise and sample drift induced image distortion ∼3.2 pm, suggesting the tilt effect could be dominant for the quantitative analysis of ABF images. The artifact depends on the crystal mistilt angle, specimen thickness, defocus, convergence angle and uncorrected aberration. Our study provides useful insights into detecting and correcting tilt effects during both experiment operation and data analysis to extract the real structure information and avoid mis-interpretations of Atomic structure as well as the properties such as oxygen octahedral distortion/shift.
-
picometer scale Atom Position analysis in annular bright field stem imaging
arXiv: Materials Science, 2017Co-Authors: Peng Gao, Akihito Kumamoto, Ryo Ishikawa, Nathan R Lugg, Naoya Shibata, Yuichi IkuharaAbstract:We study the effects of specimen mistilt on the picometer-scale measurement of local structure by combing experiment and simulation in annular bright-field scanning transmission electron microscopy (ABF-STEM). A relative distance measurement method is proposed to separate the tilt effects from the scan noise and scan distortion. We find that under a typical experimental condition a small specimen tilt (~6 mrad) in 25 nm thick SrTiO3 along [001] causes 11.9 pm artificial displacement between O and Sr/TiO columns in ABF image, which is more than 3 times of scan noise and sample drift induced image distortion ~3.2 pm, suggesting the tilt effect could be dominant for the quantitative analysis of ABF images. The artifact depends the crystal mistilt angle, specimen thickness, defocus, convergence angle and uncorrected aberration. Our study provides useful insights into detecting and correcting tilt effects during both experiment operation and data analysis to extract the real structure information and avoid mis-interpretations of Atomic structure as well as the properties such as oxygen octahedral distortion/shift.
Gang Liu - One of the best experts on this subject based on the ideXlab platform.
-
Substituent Position effect on the properties of new unsymmetrical isomeric diarylethenes having a chlorine Atom
Journal of Photochemistry and Photobiology A-chemistry, 2008Co-Authors: Congbin Fan, Gang Liu, Tianshe YangAbstract:Abstract Three new unsymmetrical photochromic diarylethenes bearing a chlorine Atom at para-, meta- and ortho-Position of one terminal benzene ring, namely {1-(2-methyl-5-phenyl-3-thienyl)-2-[2-methyl-5-(4-chlorophenyl)-3-thienyl]}perfluorocyclopentene (para 1o), {1-(2-methyl-5-phenyl-3-thienyl)-2-[2-methyl-5-(3-chlorophenyl)-3-thienyl]}perfluorocyclopentene (meta 2o), and {1-(2-methyl-5-phenyl-3-thienyl)-2-[2-methyl-5-(2-chlorophenyl) -3-thienyl]}perfluorocyclopentene (ortho 3o), have been synthesized. The substituent Position effect on their properties, including photochromism, fluorescence both in solution and in PMMA amorphous film and their electrochemical properties were investigated in detail. The results elucidated that the chlorine Atom and its substituent Position had a remarkable effect on the absorption characteristics, photochromic reactivity, fluorescence, as well as the electrochemical performances of these diarylethene compounds. For diarylethenes 1, 2 and 3, the cycloreversion quantum yields were gradually increased when the chlorine Atom was attached to the para-, meta- and ortho-Positions of the one terminal benzene rings; but their molar absorption coefficients both of their open-ring and closed-ring isomers were remarkably decreased. The fluorescent properties of para-substituted diarylethene embedded in poly(methyl methacylate) (PMMA) amorphous film showed good fluorescent switches (quenched to 28%). Furthermore, the cyclic voltammograms experiments elucidated that the electrochemical properties of these diarylethene derivatives were also remarkably dependent on the chlorine Atom Position effect, which may be attributed to the different electron-inducing ability and steric effect when the chlorine Atom was substituted on the different Position of the terminal benzene ring.
-
Synthesis and chlorine Atom Position effect on the properties of unsymmetrical photochromic diarylethenes
Journal of Photochemistry and Photobiology A: Chemistry, 2008Co-Authors: Liu‐shui Yan, Zhen-dong Wen, Gang Liu, Liang ShenAbstract:Abstract Unsymmetrical photochromic diarylethenes 1o–4o have been synthesized, which diarylethenes 1o–3o have a chlorine Atom at ortho-, meta- and para-Position of the terminal phenyl ring, respectively. The substituent Position effect of chlorine Atom on their properties, including photochromism both in solution and in the single crystalline phase and their electrochemical properties were investigated in detail. The results elucidated that the chlorine Atom and its substituted Position had significantly affected on the absorption characteristics, photochromic reactivity as well as the electrochemical performances of these diarylethene compounds. When the chlorine Atom was introduced into the phenyl ring of these diarylethene systems, the cycloreversion quantum yields were effectively depressed; but, the molar absorption coefficients of the open-ring isomer and the differences of oxidation potential onsets between the open- and closed-ring isomers of these diarylethenes were significantly increased. Moreover, the Position of the chlorine Atom had also influenced evidently the above optical and electrochemical features.
Liang Shen - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis and chlorine Atom Position effect on the properties of unsymmetrical photochromic diarylethenes
Journal of Photochemistry and Photobiology A: Chemistry, 2008Co-Authors: Liu‐shui Yan, Zhen-dong Wen, Gang Liu, Liang ShenAbstract:Abstract Unsymmetrical photochromic diarylethenes 1o–4o have been synthesized, which diarylethenes 1o–3o have a chlorine Atom at ortho-, meta- and para-Position of the terminal phenyl ring, respectively. The substituent Position effect of chlorine Atom on their properties, including photochromism both in solution and in the single crystalline phase and their electrochemical properties were investigated in detail. The results elucidated that the chlorine Atom and its substituted Position had significantly affected on the absorption characteristics, photochromic reactivity as well as the electrochemical performances of these diarylethene compounds. When the chlorine Atom was introduced into the phenyl ring of these diarylethene systems, the cycloreversion quantum yields were effectively depressed; but, the molar absorption coefficients of the open-ring isomer and the differences of oxidation potential onsets between the open- and closed-ring isomers of these diarylethenes were significantly increased. Moreover, the Position of the chlorine Atom had also influenced evidently the above optical and electrochemical features.
Chengfu Wei - One of the best experts on this subject based on the ideXlab platform.
-
research on the optical band Positions spin hamiltonian parameters and Atom Position parameter of co2 ion in cdse crystal
Journal of Magnetism and Magnetic Materials, 2015Co-Authors: Yang Mei, Wen-chen Zheng, Renming Peng, Chengfu WeiAbstract:Abstract The optical band Positions and EPR (or spin-Hamiltonian) parameters (g factors g//, g⊥ and zero-field splitting D) of Co2+ ion in the trigonally-distorted tetrahedral Cd2+ site of CdSe crystal are calculated simultaneously from the complete diagonalization (of energy matrix) method (CDM) based on the two-spin–orbit-parameter model. This model contains the contributions to the spectral data from both the spin–orbit parameters of central dn ion (i.e., one-spin–orbit-parameter model) in the conventional crystal-field theory and that of ligand ions via covalence effect. The calculated 12 optical band Positions and three spin-Hamiltonian parameters using four adjustable parameters show reasonable agreement with the experimental values. The local Atom-Position parameter uloc (where the corresponding parameter u in the host CdSe crystal is unlikely) in the Co2+ center is also estimated from the calculations. The calculations of these spectral data from the CDM based on the conventional one-spin–orbit parameter model are also made for comparison. It is found that the calculated optical band Positions are also close to the experimental values, but the calculated spin-Hamiltonian parameters are in poor agreement with the observed values. So, for the unified and reasonable calculations of optical and EPR data of dn ions in crystals (in particular, in the cases of ligand with large spin–orbit parameter), the CDM based on the two-spin–orbit-parameter model should be applied.