The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
Timothy S Fisher - One of the best experts on this subject based on the ideXlab platform.
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extraordinary sensitivity of the electronic structure and properties of single walled carbon nanotubes to Molecular Charge transfer
Journal of Physical Chemistry C, 2008Co-Authors: Rakesh Voggu, Chandra Sekhar Rout, Aaron D Franklin, Timothy S FisherAbstract:Interaction of single-walled carbon nanotubes with electron-donor and -acceptor molecules causes significant changes in the electronic and Raman spectra. Electron-donating molecules such as tetrathiafulvalene and aniline cause changes opposite to those caused by electron-withdrawing molecules such as nitrobenzene and tetracyanoethylene. Thus, a proportion of the semiconducting SWNTs becomes metallic on electron donation through Molecular Charge transfer. Electrical resistivity measurements reveal a systematic variation with electron-donating or -withdrawing power of the interacting molecules.
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extraordinary sensitivity of the electronic structure and properties of single walled carbon nanotubes to Molecular Charge transfer
arXiv: Materials Science, 2008Co-Authors: Rakesh Voggu, Chandra Sekhar Rout, Aaron D Franklin, Timothy S FisherAbstract:Interaction of single-walled carbon nanotubes with electron donor and acceptor molecules causes significant changes in the electronic and Raman spectra, the relative proportion of the metallic species increasing on electron donation through Molecular Charge transfer, as also verified by electrical resistivity measurements.
Swapan K Pati - One of the best experts on this subject based on the ideXlab platform.
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Tuning the electronic and optical properties of graphene and boron-nitride quantum dots by Molecular Charge-transfer interactions: a theoretical study
Physical Chemistry Chemical Physics, 2013Co-Authors: Arkamita Bandyopadhyay, Sharma S. R. K. C. Yamijala, Swapan K PatiAbstract:Spin-polarized first-principles calculations have been performed to tune the electronic and optical properties of graphene (G) and boron-nitride (BN) quantum dots (QDs) through Molecular Charge-transfer using tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) as dopants. From our results, based on the formation energy and the distance between QDs and dopants, we infer that both the dopants are physisorbed on the QDs. Also, we find that GQDs interact strongly with the dopants compared to the BNQDs. Interestingly, although the dopants are physisorbed on QDs, their interactions lead to a decrement in the HOMO–LUMO gap of QDs by more than half of their original value. We have found a spin-polarized HOMO–LUMO gap in certain QD–dopant complexes. Mulliken population analysis, generation of density of states (DOS) and projected DOS (pDOS) plots, and optical conductivity calculations have been performed to support and understand the reasons behind our findings.
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Doping single-walled carbon nanotubes through Molecular Charge-transfer: a theoretical study
Nanoscale, 2010Co-Authors: Arun K Manna, Swapan K PatiAbstract:We study the effect of the Molecular Charge transfer on the electronic structure of metallic (5,5) and semiconducting (8,0) single-walled carbon nanotubes (SWNTs) induced by surface adsorption of various organic donor–acceptor molecules of different affinities using ab initio density functional theory. Our results, obtained from first-principles spin-polarized calculations show that the adsorption of molecules with different affinities reflects the difference in interaction strength that measure the overall energy of adsorption. Moderate values of the binding energy of these surface adsorbed Molecular Charge-transfer complexes suggest that the nature of interaction is in the physisorption regime, and mainly governs by Coulombic forces. We also find that the large band gap of semiconducting (8,0) SWNT can be tuned through the surface adsorption of selective organic molecules which gives rise to mid-gap localized Molecular levels near the Fermi energy with tuning of band gap region. Interestingly, we find that the metallic (5,5) SWNT and semiconducting (8,0) SWNT turn into semiconducting and metallic nanotubes respectively in presence of selective surface adsorbed molecules, corroborating recent experimental findings. We also suggest that these Charge transfer effect can be probed through optical conductivity measurement, as the low-frequency profiles are affected by Charge transfer.
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tuning the electronic structure of graphene by Molecular Charge transfer a computational study
Chemistry-an Asian Journal, 2009Co-Authors: Arun K Manna, Swapan K PatiAbstract:Insulating semiconducting conductors? The electronic properties of graphene can be tuned through Molecular Charge transfer, induced by organic electron donor (acceptor), TTF (TCNE, TCNQ), molecules. Such Molecular-Charge-transfer process has significant effects on optical and transport properties, in particular the characteristic Raman spectra of graphene. We have studied the modification in the electronic structure, as well as optical and transport properties of graphene induced by Molecular Charge transfer using ab initio density functional theory. Our results from first-principles spin-polarized calculations are compared with those of the available data from Raman spectroscopic studies of modified graphene systems. We find that electron donor and acceptor molecules adsorbed onto the graphene surface exhibit effective Molecular Charge transfer, giving rise to mid-gap Molecular levels with tuning of the band gap region near the Dirac point. The Molecular Charge transfer causes the stiffening or softening of the Raman G-band frequency in graphene, and we find that it also has a significant impact on the intensity ratio of the D- to G-band, corroborating experimental findings. We suggest that these Charge transfer mechanisms can be probed through the low-frequency profile of the optical conductivity.
Rakesh Voggu - One of the best experts on this subject based on the ideXlab platform.
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extraordinary sensitivity of the electronic structure and properties of single walled carbon nanotubes to Molecular Charge transfer
Journal of Physical Chemistry C, 2008Co-Authors: Rakesh Voggu, Chandra Sekhar Rout, Aaron D Franklin, Timothy S FisherAbstract:Interaction of single-walled carbon nanotubes with electron-donor and -acceptor molecules causes significant changes in the electronic and Raman spectra. Electron-donating molecules such as tetrathiafulvalene and aniline cause changes opposite to those caused by electron-withdrawing molecules such as nitrobenzene and tetracyanoethylene. Thus, a proportion of the semiconducting SWNTs becomes metallic on electron donation through Molecular Charge transfer. Electrical resistivity measurements reveal a systematic variation with electron-donating or -withdrawing power of the interacting molecules.
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extraordinary sensitivity of the electronic structure and properties of single walled carbon nanotubes to Molecular Charge transfer
arXiv: Materials Science, 2008Co-Authors: Rakesh Voggu, Chandra Sekhar Rout, Aaron D Franklin, Timothy S FisherAbstract:Interaction of single-walled carbon nanotubes with electron donor and acceptor molecules causes significant changes in the electronic and Raman spectra, the relative proportion of the metallic species increasing on electron donation through Molecular Charge transfer, as also verified by electrical resistivity measurements.
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changes in the electronic structure and properties of graphene induced by Molecular Charge transfer
arXiv: Materials Science, 2008Co-Authors: Rakesh Voggu, Chandra Sekhar RoutAbstract:Interaction with electron donor and acceptor molecules such as aniline and nitrobenzene brings about marked changes in the Raman spectrum and the electronic structure of graphene, prepared by the exfoliation of graphitic oxide.
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Changes in the electronic structure and properties of graphene induced by Molecular Charge-transfer.
Chemical communications (Cambridge England), 2008Co-Authors: Barun Das, Rakesh Voggu, Chandra Sekhar Rout, C. N. R. RaoAbstract:Interaction with electron-donor and -acceptor molecules such as aniline and nitrobenzene brings about marked changes in the D, G, G' and 2D bands of the Raman spectrum and the electronic structure of graphene, prepared by the exfoliation of graphitic oxide.
M. Kurmoo - One of the best experts on this subject based on the ideXlab platform.
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Temperature dependence (300 to 10K) of the structural and electronic properties of the Molecular Charge-transfer salt (BEDT-TTF)3 Cl2,2H2O
Synthetic Metals, 1995Co-Authors: Daniel Chasseau, S. Hebrard, V. Hays, G. Bravic, Jacques Gaultier, Laurent Ducasse, M. KurmooAbstract:Abstract The crystal and electronic structure of the Molecular Charge-transfer salt (BEDT-TTF) 3 Cl 2 2H 2 O was determined at 10, 130, 190 and 295K. The thermal expansion has been evaluated from measurements of cell parameters between 10 and 295K.
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Temperature dependence (300 to 12k) of the structural and electronic properties of the Molecular Charge - transfer salt ET/sub 3/Cl/sub 2/,2H/sub 2/O
International Conference on Science and Technology of Synthetic Metals, 1994Co-Authors: Daniel Chasseau, S. Hebrard, V. Hays, G. Bravic, Jacques Gaultier, L. Ducassse, M. KurmooAbstract:Summary form only given. The Molecular Charge-transfer salt (BEDT-TFF) /sub 3/Cl/sub 2/,2H/sub 2/O undergoes a metal-insulator transition at about 100K and becomes superconducting under pressure (10kbar) at 5K. The isobaric thermal expansions are calculated from the values of the lattice parameters (300 to 12K at ambient pressure). The electronic properties are deduced from the ambient pressure (295, 130 and 12K) crystal structures.
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High pressure and low temperature X-ray crystallography: the crystal structure of the Molecular Charge transfer salt α'- (bis(ethylenedithio)-tetrathiafulvalene)2AuBr2
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 1993Co-Authors: Daniel Chasseau, Jacques Gaultier, Laurent Ducasse, G. Bravic, M. KurmooAbstract:An X-ray diffraction technique is described that allows determination of crystal structure and the variation of lattice parameters of single crystals as a function of hydrostatic pressure up to 14 kbar and of temperature from 300 K to 12 K. As an example of the technique results are presented on the Molecular Charge transfer salt $\alpha ^{\prime}$-(BEDT-TTF)$\_{2}$AuBr$\_{2}$ (BEDT-TTF = bis(ethylenedithio)-tetrathiafulvalene) to elucidate the nature of a structural phase transition which occurs at 250 K at ambient pressure and 7 kbar at 300 K. The transition, of second order, is characterized by the appearance of ${\textstyle\frac{1}{2}}$b$^{\ast}$ superlattice reflections at high pressure or low temperature but without any drastic change in the basic crystal structure. The isobaric thermal expansions and the isothermal compressibilities are anisotropic, being larger along a than along b and c, though of different magnitudes and directional properties, i.e. the effect of applying pressure at ambient temperature is not equivalent to lowering the temperature at ambient pressure. Transfer integral calculations show that marked dimerization along the stacking axis, already present at 300 K, is related to electronic localization.
Arun K Manna - One of the best experts on this subject based on the ideXlab platform.
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Doping single-walled carbon nanotubes through Molecular Charge-transfer: a theoretical study
Nanoscale, 2010Co-Authors: Arun K Manna, Swapan K PatiAbstract:We study the effect of the Molecular Charge transfer on the electronic structure of metallic (5,5) and semiconducting (8,0) single-walled carbon nanotubes (SWNTs) induced by surface adsorption of various organic donor–acceptor molecules of different affinities using ab initio density functional theory. Our results, obtained from first-principles spin-polarized calculations show that the adsorption of molecules with different affinities reflects the difference in interaction strength that measure the overall energy of adsorption. Moderate values of the binding energy of these surface adsorbed Molecular Charge-transfer complexes suggest that the nature of interaction is in the physisorption regime, and mainly governs by Coulombic forces. We also find that the large band gap of semiconducting (8,0) SWNT can be tuned through the surface adsorption of selective organic molecules which gives rise to mid-gap localized Molecular levels near the Fermi energy with tuning of band gap region. Interestingly, we find that the metallic (5,5) SWNT and semiconducting (8,0) SWNT turn into semiconducting and metallic nanotubes respectively in presence of selective surface adsorbed molecules, corroborating recent experimental findings. We also suggest that these Charge transfer effect can be probed through optical conductivity measurement, as the low-frequency profiles are affected by Charge transfer.
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tuning the electronic structure of graphene by Molecular Charge transfer a computational study
Chemistry-an Asian Journal, 2009Co-Authors: Arun K Manna, Swapan K PatiAbstract:Insulating semiconducting conductors? The electronic properties of graphene can be tuned through Molecular Charge transfer, induced by organic electron donor (acceptor), TTF (TCNE, TCNQ), molecules. Such Molecular-Charge-transfer process has significant effects on optical and transport properties, in particular the characteristic Raman spectra of graphene. We have studied the modification in the electronic structure, as well as optical and transport properties of graphene induced by Molecular Charge transfer using ab initio density functional theory. Our results from first-principles spin-polarized calculations are compared with those of the available data from Raman spectroscopic studies of modified graphene systems. We find that electron donor and acceptor molecules adsorbed onto the graphene surface exhibit effective Molecular Charge transfer, giving rise to mid-gap Molecular levels with tuning of the band gap region near the Dirac point. The Molecular Charge transfer causes the stiffening or softening of the Raman G-band frequency in graphene, and we find that it also has a significant impact on the intensity ratio of the D- to G-band, corroborating experimental findings. We suggest that these Charge transfer mechanisms can be probed through the low-frequency profile of the optical conductivity.