The Experts below are selected from a list of 101271 Experts worldwide ranked by ideXlab platform
Michael L Steigerwald - One of the best experts on this subject based on the ideXlab platform.
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influence of Molecular Conformation on electron transport in giant conjugated macrocycles
Journal of the American Chemical Society, 2018Co-Authors: Melissa Ball, Michael L Steigerwald, Colin Nuckolls, Boyuan Zhang, Daniel W Paley, Virginia Cary RitterAbstract:We describe here the direct connection between the Molecular Conformation of a conjugated macrocycle and its macroscopic charge transport properties. We incorporate chiral, helical perylene diimide ribbons into the two separate macrocycles as the n-type, electron transporting material. As the macrocycles’ films and electronic structures are analogous, the important finding is that the macrocycles’ Molecular structures and their associated dynamics determine device performance in organic field effect transistors. We show the more flexible macrocycle has a 4-fold increase in electron mobility in field effect transistor devices. Using a combination of spectroscopy and density functional theory calculations, we find that the origin of the difference in device performance is the ability of more flexible isomer to make interMolecular contacts relative to the more rigid counterpart.
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Dependence of single-molecule junction conductance on Molecular Conformation
Nature, 2006Co-Authors: Latha Venkataraman, Jens Klare, Mark S. Hybertsen, Colin Nuckolls, Michael L SteigerwaldAbstract:Since it was first suggested that a single molecule might function as an active electronic component, a number of techniques have been developed to measure the charge transport properties of single molecules. Although scanning tunnelling microscopy observations under high vacuum conditions can allow stable measurements of electron transport, most measurements of a single molecule bonded in a metal-molecule-metal junction exhibit relatively large variations in conductance. As a result, even simple predictions about how molecules behave in such junctions have still not been rigorously tested. For instance, it is well known that the tunnelling current passing through a molecule depends on its Conformation; but although some experiments have verified this effect, a comprehensive mapping of how junction conductance changes with Molecular Conformation is not yet available. In the simple case of a biphenyl--a molecule with two phenyl rings linked by a single C-C bond--conductance is expected to change with the relative twist angle between the two rings, with the planar Conformation having the highest conductance. Here we use amine link groups to form single-molecule junctions with more reproducible current-voltage characteristics. This allows us to extract average conductance values from thousands of individual measurements on a series of seven biphenyl molecules with different ring substitutions that alter the twist angle of the molecules. We find that the conductance for the series decreases with increasing twist angle, consistent with a cosine-squared relation predicted for transport through pi-conjugated biphenyl systems.
Colin Nuckolls - One of the best experts on this subject based on the ideXlab platform.
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influence of Molecular Conformation on electron transport in giant conjugated macrocycles
Journal of the American Chemical Society, 2018Co-Authors: Melissa Ball, Michael L Steigerwald, Colin Nuckolls, Boyuan Zhang, Daniel W Paley, Virginia Cary RitterAbstract:We describe here the direct connection between the Molecular Conformation of a conjugated macrocycle and its macroscopic charge transport properties. We incorporate chiral, helical perylene diimide ribbons into the two separate macrocycles as the n-type, electron transporting material. As the macrocycles’ films and electronic structures are analogous, the important finding is that the macrocycles’ Molecular structures and their associated dynamics determine device performance in organic field effect transistors. We show the more flexible macrocycle has a 4-fold increase in electron mobility in field effect transistor devices. Using a combination of spectroscopy and density functional theory calculations, we find that the origin of the difference in device performance is the ability of more flexible isomer to make interMolecular contacts relative to the more rigid counterpart.
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Dependence of single-molecule junction conductance on Molecular Conformation
Nature, 2006Co-Authors: Latha Venkataraman, Jens Klare, Mark S. Hybertsen, Colin Nuckolls, Michael L SteigerwaldAbstract:Since it was first suggested that a single molecule might function as an active electronic component, a number of techniques have been developed to measure the charge transport properties of single molecules. Although scanning tunnelling microscopy observations under high vacuum conditions can allow stable measurements of electron transport, most measurements of a single molecule bonded in a metal-molecule-metal junction exhibit relatively large variations in conductance. As a result, even simple predictions about how molecules behave in such junctions have still not been rigorously tested. For instance, it is well known that the tunnelling current passing through a molecule depends on its Conformation; but although some experiments have verified this effect, a comprehensive mapping of how junction conductance changes with Molecular Conformation is not yet available. In the simple case of a biphenyl--a molecule with two phenyl rings linked by a single C-C bond--conductance is expected to change with the relative twist angle between the two rings, with the planar Conformation having the highest conductance. Here we use amine link groups to form single-molecule junctions with more reproducible current-voltage characteristics. This allows us to extract average conductance values from thousands of individual measurements on a series of seven biphenyl molecules with different ring substitutions that alter the twist angle of the molecules. We find that the conductance for the series decreases with increasing twist angle, consistent with a cosine-squared relation predicted for transport through pi-conjugated biphenyl systems.
Latha Venkataraman - One of the best experts on this subject based on the ideXlab platform.
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Dependence of single-molecule junction conductance on Molecular Conformation
Nature, 2006Co-Authors: Latha Venkataraman, Jens Klare, Mark S. Hybertsen, Colin Nuckolls, Michael L SteigerwaldAbstract:Since it was first suggested that a single molecule might function as an active electronic component, a number of techniques have been developed to measure the charge transport properties of single molecules. Although scanning tunnelling microscopy observations under high vacuum conditions can allow stable measurements of electron transport, most measurements of a single molecule bonded in a metal-molecule-metal junction exhibit relatively large variations in conductance. As a result, even simple predictions about how molecules behave in such junctions have still not been rigorously tested. For instance, it is well known that the tunnelling current passing through a molecule depends on its Conformation; but although some experiments have verified this effect, a comprehensive mapping of how junction conductance changes with Molecular Conformation is not yet available. In the simple case of a biphenyl--a molecule with two phenyl rings linked by a single C-C bond--conductance is expected to change with the relative twist angle between the two rings, with the planar Conformation having the highest conductance. Here we use amine link groups to form single-molecule junctions with more reproducible current-voltage characteristics. This allows us to extract average conductance values from thousands of individual measurements on a series of seven biphenyl molecules with different ring substitutions that alter the twist angle of the molecules. We find that the conductance for the series decreases with increasing twist angle, consistent with a cosine-squared relation predicted for transport through pi-conjugated biphenyl systems.
Yujun Zhao - One of the best experts on this subject based on the ideXlab platform.
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geometrical eigen subspace framework based Molecular Conformation representation for efficient structure recognition and comparison
Journal of Chemical Physics, 2017Co-Authors: Xiaobao Yang, Yujun ZhaoAbstract:We have developed an extended distance matrix approach to study the Molecular geometric configuration through spectral decomposition. It is shown that the positions of all atoms in the eigen-space can be specified precisely by their eigen-coordinates, while the refined atomic eigen-subspace projection array adopted in our approach is demonstrated to be a competent invariant in structure comparison. Furthermore, a visual eigen-subspace projection function (EPF) is derived to characterize the surrounding configuration of an atom naturally. A complete set of atomic EPFs constitute an intrinsic representation of Molecular Conformation, based on which the interatomic EPF distance and interMolecular EPF distance can be reasonably defined. Exemplified with a few cases, the interMolecular EPF distance shows exceptional rationality and efficiency in structure recognition and comparison.
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geometrical eigen subspace framework based Molecular Conformation representation for efficient structure recognition and comparison
arXiv: Materials Science, 2017Co-Authors: Xiaobao Yang, Yujun ZhaoAbstract:We have developed an extended distance matrix approach to study the Molecular geometric configuration through spectral decomposition. It is shown that the positions of all atoms in the eigen-space can be specified precisely by their eigen-coordinates, while the refined atomic eigen-subspace projection array adopted in our approach is demonstrated to be a competent invariant in structure comparison. Furthermore, a visual eigen-subspace projection function (EPF) is derived to characterize the surrounding configuration of an atom naturally. A complete set of atomic EPFs constitute an intrinsic representation of Molecular Conformation, based on which the interatomic EPF distance and interMolecular EPF distance in the eigen-space can be reasonably defined. Exemplified with a few cases, the interMolecular EPF distance shows exceptional rationality and efficiency in structure recognition and comparison.
Elke Scheer - One of the best experts on this subject based on the ideXlab platform.
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conductance and vibrational states of single molecule junctions controlled by mechanical stretching and material variation
Physical Review Letters, 2011Co-Authors: Hyunwook Song, Florian Strigl, Hansfridtjof Pernau, Elke ScheerAbstract:The changes of Molecular Conformation, contact geometry, and metal-molecule bonding are revealed by inelastic-electron-tunneling spectroscopy measurements characterizing the Molecular vibrational modes and the metal-phonon modes in alkanedithiol Molecular junctions at low temperature. Combining inelastic-electron-tunneling spectroscopy with mechanical control and electrode material variation (Au or Pt) enables separating the influence of contact geometry and of Molecular Conformation. The mechanical strain of different electrode materials can be imposed onto the molecule, opening a new route for controlling the charge transport through individual molecules.
