The Experts below are selected from a list of 20562 Experts worldwide ranked by ideXlab platform
Myung-hwan Whangbo - One of the best experts on this subject based on the ideXlab platform.
-
Characterization of the surfaces of the conducting salts α-(BEDT-TTF)2X (X = I3, IBr2) by scanning tunneling and atomic force microscopy
Synthetic Metals, 1994Co-Authors: S. N. Magonov, G. Bar, Jeffrey A. Paradis, J. Ren, H.-j. Cantov, Myung-hwan WhangboAbstract:Abstract We carried out scanning tunneling microscopy (STM) and atomic force microscopy (AFM) measurements of the α-(BEDT-TTF) 2 X (X = I 3 and IBr 2 ) salts and interpreted the results on the basis of the partial density ϱ ( r 0 , e f ) and total electron density ϱ ( r 0 ) plots calculated by the extended Huckel tight-binding method. Large scale STM images show surface modifications induced by the tip-surface interactions. The STM and AFM images show the patterns of the cation layers. The ϱ ( r 0 , e f ) plots are essential in relating the features of the observed atomic-resolution STM images to the surface structures and show that the Ethylene-Group hydrogen atoms of the protruded cations dominate the STM images. The dependence of the STM images of the BEDT-TTF salts on the tunneling gap resistance is probably caused by the tip-induced conformational change of the Ethylene Groups of the surface cations.
-
Scanning tunneling and atomic microscopy images of organic salt conductor (BEDT-TTF)2TlHg(SCN)4
The Journal of Physical Chemistry, 1993Co-Authors: S. N. Magonov, G. Bar, Hans-joachim Cantow, Jeffrey A. Paradis, J. Ren, Myung-hwan Whangbo, Eduard B. YagubskiiAbstract:Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) images were obtained for the organic conducting salt (BEDT-TTF)[sub 2]TlHg(SCN)[sub 4], in which layers of the cations BEDT-TTF[sup 0.5+] alternate with layers of the anions TlHgSCN[sub 4][sup 2]. These images were interpreted on the basis of the partial and total electron density plots of a cation layer calculated by the extended Hueckel tight-binding (EHTB) electronic band structure method. The observed STM and AFM patterns are dominated by the Ethylene Group hydrogen atoms of the cations. The patterns and intensity of the STM images vary as a function of the gap resistance. A probable cause for this observation was discussed from the viewpoint of a conformational change in the Ethylene Groups of BEDT-TTF. Our work provides a strong support for the use of partial and total electron density plots in the interpretation of STM and AFM images. 24 refs., 7 figs.
S. N. Magonov - One of the best experts on this subject based on the ideXlab platform.
-
Characterization of the surfaces of the conducting salts α-(BEDT-TTF)2X (X = I3, IBr2) by scanning tunneling and atomic force microscopy
Synthetic Metals, 1994Co-Authors: S. N. Magonov, G. Bar, Jeffrey A. Paradis, J. Ren, H.-j. Cantov, Myung-hwan WhangboAbstract:Abstract We carried out scanning tunneling microscopy (STM) and atomic force microscopy (AFM) measurements of the α-(BEDT-TTF) 2 X (X = I 3 and IBr 2 ) salts and interpreted the results on the basis of the partial density ϱ ( r 0 , e f ) and total electron density ϱ ( r 0 ) plots calculated by the extended Huckel tight-binding method. Large scale STM images show surface modifications induced by the tip-surface interactions. The STM and AFM images show the patterns of the cation layers. The ϱ ( r 0 , e f ) plots are essential in relating the features of the observed atomic-resolution STM images to the surface structures and show that the Ethylene-Group hydrogen atoms of the protruded cations dominate the STM images. The dependence of the STM images of the BEDT-TTF salts on the tunneling gap resistance is probably caused by the tip-induced conformational change of the Ethylene Groups of the surface cations.
-
Scanning tunneling and atomic microscopy images of organic salt conductor (BEDT-TTF)2TlHg(SCN)4
The Journal of Physical Chemistry, 1993Co-Authors: S. N. Magonov, G. Bar, Hans-joachim Cantow, Jeffrey A. Paradis, J. Ren, Myung-hwan Whangbo, Eduard B. YagubskiiAbstract:Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) images were obtained for the organic conducting salt (BEDT-TTF)[sub 2]TlHg(SCN)[sub 4], in which layers of the cations BEDT-TTF[sup 0.5+] alternate with layers of the anions TlHgSCN[sub 4][sup 2]. These images were interpreted on the basis of the partial and total electron density plots of a cation layer calculated by the extended Hueckel tight-binding (EHTB) electronic band structure method. The observed STM and AFM patterns are dominated by the Ethylene Group hydrogen atoms of the cations. The patterns and intensity of the STM images vary as a function of the gap resistance. A probable cause for this observation was discussed from the viewpoint of a conformational change in the Ethylene Groups of BEDT-TTF. Our work provides a strong support for the use of partial and total electron density plots in the interpretation of STM and AFM images. 24 refs., 7 figs.
D Schweitzer - One of the best experts on this subject based on the ideXlab platform.
-
determining Ethylene Group disorder levels in κ bedt ttf 2 cu n c n 2 br
Physical Review B, 2007Co-Authors: A U B Wolter, R Feyerherm, E Dudzik, S Sullow, Ch Strack, M Lang, D SchweitzerAbstract:We present a detailed structural investigation of the organic superconductor $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{C}\mathrm{N})}_{2}]\mathrm{Br}$ at temperatures $T$ from $9\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Anomalies in the $T$ dependence of the lattice parameters are associated with a glasslike transition previously reported at ${T}_{g}=77\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. From structure refinements at 9, 100, and $300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, the orthorhombic crystalline symmetry, space Group $Pnma$, is established at all temperatures. Further, we extract the $T$ dependence of the occupation factor of the eclipsed conformation of the terminal Ethylene Groups of the BEDT-TTF molecule. At $300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, we find 67(2)%, with an increase to 97(3)% at $9\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. We conclude that the glasslike transition is not primarily caused by configurational freezing-out of the Ethylene Groups.
-
Determining Ethylene Group disorder levels in {kappa}-(BEDT-TTF){sub 2}Cu[N(China){sub 2}]Br
Physical Review B, 2007Co-Authors: A U B Wolter, R Feyerherm, E Dudzik, S Sullow, Ch Strack, M Lang, D SchweitzerAbstract:We present a detailed structural investigation of the organic superconductor {kappa}-(BEDT-TTF){sub 2}Cu[N(China){sub 2}]Br at temperatures T from 9 to 300 K. Anomalies in the T dependence of the lattice parameters are associated with a glasslike transition previously reported at T{sub g}=77 K. From structure refinements at 9, 100, and 300 K, the orthorhombic crystalline symmetry, space Group Pnma, is established at all temperatures. Further, we extract the T dependence of the occupation factor of the eclipsed conformation of the terminal Ethylene Groups of the BEDT-TTF molecule. At 300 K, we find 67(2)%, with an increase to 97(3)% at 9 K. We conclude that the glasslike transition is not primarily caused by configurational freezing-out of the Ethylene Groups.
M Lang - One of the best experts on this subject based on the ideXlab platform.
-
Relaxation dynamics in the one-dimensional organic charge-transfer salt δ − ( EDT − TTF − CONMe 2 ) 2 Br
Physical Review B, 2018Co-Authors: J. K. H. Fischer, M Lang, Peter Lunkenheimer, C. Leva, Stephen M. Winter, Cécile Mézière, Patrick Batail, Alois Loidl, Rudra Sekhar MannaAbstract:A detailed investigation of the charge-ordered charge-transfer salt δ−(EDT−TTF−CONMe2)2Br by thermal-expansion measurements and dielectric spectroscopy reveals three dynamic processes of relaxational character. The slowest one exhibits the characteristics of glassy freezing and is ascribed to the conformational dynamics of terminal Ethylene Groups of the organic molecules. Such a process was previously found for related charge-transfer salts where, however, the anions form polymerlike chains, in contrast to the spherical anions of the present material. Dielectric spectroscopy reveals two additional relaxational processes. The characteristics of the faster one are consistent with excitations of a one-dimensional Wigner lattice as recently observed in this material by infrared spectroscopy, which are also accompanied by conformational changes of the molecules. However, at low temperature the Ethylene-Group relaxation exhibits the cooperativity-induced dramatic slowing down that is typical for glassy freezing, while the defect-related Wigner-lattice excitation follows thermally activated behavior as expected for single-dipole relaxations.
-
determining Ethylene Group disorder levels in κ bedt ttf 2 cu n c n 2 br
Physical Review B, 2007Co-Authors: A U B Wolter, R Feyerherm, E Dudzik, S Sullow, Ch Strack, M Lang, D SchweitzerAbstract:We present a detailed structural investigation of the organic superconductor $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}\mathrm{Cu}[\mathrm{N}{(\mathrm{C}\mathrm{N})}_{2}]\mathrm{Br}$ at temperatures $T$ from $9\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Anomalies in the $T$ dependence of the lattice parameters are associated with a glasslike transition previously reported at ${T}_{g}=77\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. From structure refinements at 9, 100, and $300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, the orthorhombic crystalline symmetry, space Group $Pnma$, is established at all temperatures. Further, we extract the $T$ dependence of the occupation factor of the eclipsed conformation of the terminal Ethylene Groups of the BEDT-TTF molecule. At $300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, we find 67(2)%, with an increase to 97(3)% at $9\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. We conclude that the glasslike transition is not primarily caused by configurational freezing-out of the Ethylene Groups.
-
Determining Ethylene Group disorder levels in {kappa}-(BEDT-TTF){sub 2}Cu[N(China){sub 2}]Br
Physical Review B, 2007Co-Authors: A U B Wolter, R Feyerherm, E Dudzik, S Sullow, Ch Strack, M Lang, D SchweitzerAbstract:We present a detailed structural investigation of the organic superconductor {kappa}-(BEDT-TTF){sub 2}Cu[N(China){sub 2}]Br at temperatures T from 9 to 300 K. Anomalies in the T dependence of the lattice parameters are associated with a glasslike transition previously reported at T{sub g}=77 K. From structure refinements at 9, 100, and 300 K, the orthorhombic crystalline symmetry, space Group Pnma, is established at all temperatures. Further, we extract the T dependence of the occupation factor of the eclipsed conformation of the terminal Ethylene Groups of the BEDT-TTF molecule. At 300 K, we find 67(2)%, with an increase to 97(3)% at 9 K. We conclude that the glasslike transition is not primarily caused by configurational freezing-out of the Ethylene Groups.
J. K. H. Fischer - One of the best experts on this subject based on the ideXlab platform.
-
Relaxation dynamics in the one-dimensional organic charge-transfer salt δ − ( EDT − TTF − CONMe 2 ) 2 Br
Physical Review B, 2018Co-Authors: J. K. H. Fischer, M Lang, Peter Lunkenheimer, C. Leva, Stephen M. Winter, Cécile Mézière, Patrick Batail, Alois Loidl, Rudra Sekhar MannaAbstract:A detailed investigation of the charge-ordered charge-transfer salt δ−(EDT−TTF−CONMe2)2Br by thermal-expansion measurements and dielectric spectroscopy reveals three dynamic processes of relaxational character. The slowest one exhibits the characteristics of glassy freezing and is ascribed to the conformational dynamics of terminal Ethylene Groups of the organic molecules. Such a process was previously found for related charge-transfer salts where, however, the anions form polymerlike chains, in contrast to the spherical anions of the present material. Dielectric spectroscopy reveals two additional relaxational processes. The characteristics of the faster one are consistent with excitations of a one-dimensional Wigner lattice as recently observed in this material by infrared spectroscopy, which are also accompanied by conformational changes of the molecules. However, at low temperature the Ethylene-Group relaxation exhibits the cooperativity-induced dramatic slowing down that is typical for glassy freezing, while the defect-related Wigner-lattice excitation follows thermally activated behavior as expected for single-dipole relaxations.
-
Relaxation dynamics in the one-dimensional organic charge-transfer salt δ-(EDT-TTF-CONMe2)2Br
Physical Review B, 2018Co-Authors: J. K. H. Fischer, Peter Lunkenheimer, C. Leva, Cécile Mézière, Patrick Batail, Alois Loidl, S. Winter, M. Lang, R. MannaAbstract:A detailed investigation of the charge-ordered charge-transfer salt δ−(EDT−TTF−CONMe2)2Br by thermal-expansion measurements and dielectric spectroscopy reveals three dynamic processes of relaxational character. The slowest one exhibits the characteristics of glassy freezing and is ascribed to the conformational dynamics of terminal Ethylene Groups of the organic molecules. Such a process was previously found for related charge-transfer salts where, however, the anions form polymerlike chains, in contrast to the spherical anions of the present material. Dielectric spectroscopy reveals two additional relaxational processes. The characteristics of the faster one are consistent with excitations of a one-dimensional Wigner lattice as recently observed in this material by infrared spectroscopy, which are also accompanied by conformational changes of the molecules. However, at low temperature the Ethylene-Group relaxation exhibits the cooperativity-induced dramatic slowing down that is typical for glassy freezing, while the defect-related Wigner-lattice excitation follows thermally activated behavior as expected for single-dipole relaxations.