The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform

Francesca Terenziani - One of the best experts on this subject based on the ideXlab platform.

  • first hyperpolarizability dispersion of the octupolar molecule crystal violet multiple resonances and vibrational and solvation effects
    Journal of the American Chemical Society, 2010
    Co-Authors: Jochen Campo, Anna Painelli, Francesca Terenziani, Tanguy Van Regemorter, David Beljonne, E Goovaerts, Wim Wenseleers
    Abstract:

    The first hyperpolarizability (β) dispersion curve is measured for the first time for an octupolar nonlinear optical (NLO) molecule (crystal violet, CV) and modeled theoretically, yielding an in-depth understanding of the electronic structure and vibronic and solvation effects on such octupolar conjugated systems. Tunable wavelength hyper-Rayleigh scattering (HRS) measurements were performed on this prototypical octupolar molecule in the broad fundamental wavelength range of 620−1580 nm, showing significant shortcomings of the commonly used β dispersion models. Three well-separated β resonances involving the lowest-energy State and several higher excited States are clearly observed, including a significant contribution from a nominally one-photon forbidden transition. The experimental results for second-harmonic wavelengths above 330 nm are successfully modeled by means of a vibronically coupled essential-State Description for octupolar chromophores, developed by Terenziani et al. (J. Phys. Chem. B 2008, ...

  • symmetry breaking in octupolar chromophores solvatochromism and electroabsorption
    Journal of Physical Chemistry B, 2008
    Co-Authors: Francesca Terenziani, Cristina Sissa, Anna Painelli
    Abstract:

    In this contribution, we adopt an essential-State Description for octupolar (AD3 or DA3) chromophores (where A is an electron-acceptor and D is an electron-donor) that also accounts for the coupling of electrons to molecular vibrations and for solvation effects. The first excited State of octupolar chromophores is always multistable and can therefore support symmetry breaking. In particular, symmetry is always broken in the relaxed excited State of octupolar dyes in polar solvents, with consequent localization of the excitation on one of the dipolar molecular branches. This rationalizes the common observation of strongly solvatochromic fluorescence spectra for octupolar chromophores. The model is validated through the comparison with experimental data. The essential-State model is also adopted to derive a perturbative expression for the electroabsorption spectrum:  if compared with the formalism derived for dipolar molecules, a new term appears for octupolar chromophores, due to the field activation of an...

  • charge instability in quadrupolar chromophores symmetry breaking and solvatochromism
    Journal of the American Chemical Society, 2006
    Co-Authors: Francesca Terenziani, Anna Painelli, Claudine Katan, Marina Charlot, Mireille Blancharddesce
    Abstract:

    We present a joint theoretical and experimental work aimed to understand the spectroscopic behavior of multipolar dyes of interest for nonlinear optics (NLO) applications. In particular, we focus on the occurrence of broken-symmetry States in quadrupolar organic dyes and their spectroscopic consequences. To gain a unified Description, we have developed a model based on a few-State Description of the charge-transfer processes characterizing the low-energy physics of these systems. The model takes into account the coupling between electrons and slow degrees of freedom, namely, molecular vibrations and polar solvation coordinates. We predict the occurrence of symmetry breaking in either the ground or first excited State. In this respect, quadrupolar chromophores are classified in three different classes, with distinctively different spectroscopic behavior. Cases of true and false symmetry breaking are discriminated and discussed by making resort to nonadiabatic calculations. The theoretical model is applied ...

  • Charge Instability in Quadrupolar Chromophores: Symmetry Breaking and Solvatochromism
    Journal of the American Chemical Society, 2006
    Co-Authors: Francesca Terenziani, Anna Painelli, Claudine Katan, Marina Charlot, Mireille Blanchard-desce
    Abstract:

    We present a joint theoretical and experimental work aimed to understand the spectroscopic behavior of multipolar dyes of interest for nonlinear optics (NLO) applications. In particular, we focus on the occurrence of broken-symmetry States in quadrupolar organic dyes and their spectroscopic consequences. To gain a unified Description, we have developed a model based on a few-State Description of the charge-transfer processes characterizing the low-energy physics of these systems. The model takes into account the coupling between electrons and slow degrees of freedom, namely, molecular vibrations and polar solvation coordinates. We predict the occurrence of symmetry breaking in either the ground or first excited State. In this respect, quadrupolar chromophores are classified in three different classes, with distinctively different spectroscopic behavior. Cases of true and false symmetry breaking are discriminated and discussed by making resort to nonadiabatic calculations. The theoretical model is applied to three representative quadrupolar chromophores: their qualitatively different solvatochromic properties are connected to the presence or absence of broken-symmetry States and related to two-photon absorption (TPA) cross-sections. The proposed approach provides useful guidelines for the synthesis of dyes for TPA application and represents a general and unifying reference frame to understand energy-transfer processes in multipolar molecular systems, offering important clues to understand basic properties of materials of interest for NLO and energy-harvesting applications.

Kuniyuki Miwa - One of the best experts on this subject based on the ideXlab platform.

  • many body State Description of single molecule electroluminescence driven by a scanning tunneling microscope
    Nano Letters, 2019
    Co-Authors: Kuniyuki Miwa, Hiroshi Imada, Miyabi Imaiimada, Kensuke Kimura, Michael Y Galperin
    Abstract:

    Electron transport and optical properties of a single molecule in contact with conductive materials have attracted considerable attention because of their scientific importance and potential applications. With the recent progress in experimental techniques, especially by virtue of scanning tunneling microscope (STM)-induced light emission, where the tunneling current of the STM is used as an atomic-scale source for induction of light emission from a single molecule, it has become possible to investigate single-molecule properties at subnanometer spatial resolution. Despite extensive experimental studies, the microscopic mechanism of electronic excitation of a single molecule in STM-induced light emission has yet to be clarified. Here we present a formulation of single-molecule electroluminescence driven by electron transfer between a molecule and metal electrodes based on a many-body State representation of the molecule. The effects of intramolecular Coulomb interaction on conductance and luminescence spe...

  • many body State Description of single molecule electroluminescence driven by a scanning tunneling microscope
    Nano Letters, 2019
    Co-Authors: Kuniyuki Miwa, Hiroshi Imada, Miyabi Imaiimada, Kensuke Kimura, Michael Galperin, Yousoo Kim
    Abstract:

    Electron transport and optical properties of a single molecule in contact with conductive materials have attracted considerable attention because of their scientific importance and potential applications. With the recent progress in experimental techniques, especially by virtue of scanning tunneling microscope (STM)-induced light emission, where the tunneling current of the STM is used as an atomic-scale source for induction of light emission from a single molecule, it has become possible to investigate single-molecule properties at subnanometer spatial resolution. Despite extensive experimental studies, the microscopic mechanism of electronic excitation of a single molecule in STM-induced light emission has yet to be clarified. Here we present a formulation of single-molecule electroluminescence driven by electron transfer between a molecule and metal electrodes based on a many-body State representation of the molecule. The effects of intramolecular Coulomb interaction on conductance and luminescence spectra are investigated using the nonequilibrium Hubbard Green's function technique combined with first-principles calculations. We compare simulation results with experimental data and find that the intramolecular Coulomb interaction is crucial for reproducing recent experiments for a single phthalocyanine molecule. The developed theory provides a unified Description of the electron transport and optical properties of a single molecule in contact with metal electrodes driven out of equilibrium, and thereby, it contributes to a microscopic understanding of optoelectronic conversion in single molecules on solid surfaces and in nanometer-scale junctions.

Anna Painelli - One of the best experts on this subject based on the ideXlab platform.

  • first hyperpolarizability dispersion of the octupolar molecule crystal violet multiple resonances and vibrational and solvation effects
    Journal of the American Chemical Society, 2010
    Co-Authors: Jochen Campo, Anna Painelli, Francesca Terenziani, Tanguy Van Regemorter, David Beljonne, E Goovaerts, Wim Wenseleers
    Abstract:

    The first hyperpolarizability (β) dispersion curve is measured for the first time for an octupolar nonlinear optical (NLO) molecule (crystal violet, CV) and modeled theoretically, yielding an in-depth understanding of the electronic structure and vibronic and solvation effects on such octupolar conjugated systems. Tunable wavelength hyper-Rayleigh scattering (HRS) measurements were performed on this prototypical octupolar molecule in the broad fundamental wavelength range of 620−1580 nm, showing significant shortcomings of the commonly used β dispersion models. Three well-separated β resonances involving the lowest-energy State and several higher excited States are clearly observed, including a significant contribution from a nominally one-photon forbidden transition. The experimental results for second-harmonic wavelengths above 330 nm are successfully modeled by means of a vibronically coupled essential-State Description for octupolar chromophores, developed by Terenziani et al. (J. Phys. Chem. B 2008, ...

  • symmetry breaking in octupolar chromophores solvatochromism and electroabsorption
    Journal of Physical Chemistry B, 2008
    Co-Authors: Francesca Terenziani, Cristina Sissa, Anna Painelli
    Abstract:

    In this contribution, we adopt an essential-State Description for octupolar (AD3 or DA3) chromophores (where A is an electron-acceptor and D is an electron-donor) that also accounts for the coupling of electrons to molecular vibrations and for solvation effects. The first excited State of octupolar chromophores is always multistable and can therefore support symmetry breaking. In particular, symmetry is always broken in the relaxed excited State of octupolar dyes in polar solvents, with consequent localization of the excitation on one of the dipolar molecular branches. This rationalizes the common observation of strongly solvatochromic fluorescence spectra for octupolar chromophores. The model is validated through the comparison with experimental data. The essential-State model is also adopted to derive a perturbative expression for the electroabsorption spectrum:  if compared with the formalism derived for dipolar molecules, a new term appears for octupolar chromophores, due to the field activation of an...

  • charge instability in quadrupolar chromophores symmetry breaking and solvatochromism
    Journal of the American Chemical Society, 2006
    Co-Authors: Francesca Terenziani, Anna Painelli, Claudine Katan, Marina Charlot, Mireille Blancharddesce
    Abstract:

    We present a joint theoretical and experimental work aimed to understand the spectroscopic behavior of multipolar dyes of interest for nonlinear optics (NLO) applications. In particular, we focus on the occurrence of broken-symmetry States in quadrupolar organic dyes and their spectroscopic consequences. To gain a unified Description, we have developed a model based on a few-State Description of the charge-transfer processes characterizing the low-energy physics of these systems. The model takes into account the coupling between electrons and slow degrees of freedom, namely, molecular vibrations and polar solvation coordinates. We predict the occurrence of symmetry breaking in either the ground or first excited State. In this respect, quadrupolar chromophores are classified in three different classes, with distinctively different spectroscopic behavior. Cases of true and false symmetry breaking are discriminated and discussed by making resort to nonadiabatic calculations. The theoretical model is applied ...

  • Charge Instability in Quadrupolar Chromophores: Symmetry Breaking and Solvatochromism
    Journal of the American Chemical Society, 2006
    Co-Authors: Francesca Terenziani, Anna Painelli, Claudine Katan, Marina Charlot, Mireille Blanchard-desce
    Abstract:

    We present a joint theoretical and experimental work aimed to understand the spectroscopic behavior of multipolar dyes of interest for nonlinear optics (NLO) applications. In particular, we focus on the occurrence of broken-symmetry States in quadrupolar organic dyes and their spectroscopic consequences. To gain a unified Description, we have developed a model based on a few-State Description of the charge-transfer processes characterizing the low-energy physics of these systems. The model takes into account the coupling between electrons and slow degrees of freedom, namely, molecular vibrations and polar solvation coordinates. We predict the occurrence of symmetry breaking in either the ground or first excited State. In this respect, quadrupolar chromophores are classified in three different classes, with distinctively different spectroscopic behavior. Cases of true and false symmetry breaking are discriminated and discussed by making resort to nonadiabatic calculations. The theoretical model is applied to three representative quadrupolar chromophores: their qualitatively different solvatochromic properties are connected to the presence or absence of broken-symmetry States and related to two-photon absorption (TPA) cross-sections. The proposed approach provides useful guidelines for the synthesis of dyes for TPA application and represents a general and unifying reference frame to understand energy-transfer processes in multipolar molecular systems, offering important clues to understand basic properties of materials of interest for NLO and energy-harvesting applications.

Michael Y Galperin - One of the best experts on this subject based on the ideXlab platform.

  • many body State Description of single molecule electroluminescence driven by a scanning tunneling microscope
    Nano Letters, 2019
    Co-Authors: Kuniyuki Miwa, Hiroshi Imada, Miyabi Imaiimada, Kensuke Kimura, Michael Y Galperin
    Abstract:

    Electron transport and optical properties of a single molecule in contact with conductive materials have attracted considerable attention because of their scientific importance and potential applications. With the recent progress in experimental techniques, especially by virtue of scanning tunneling microscope (STM)-induced light emission, where the tunneling current of the STM is used as an atomic-scale source for induction of light emission from a single molecule, it has become possible to investigate single-molecule properties at subnanometer spatial resolution. Despite extensive experimental studies, the microscopic mechanism of electronic excitation of a single molecule in STM-induced light emission has yet to be clarified. Here we present a formulation of single-molecule electroluminescence driven by electron transfer between a molecule and metal electrodes based on a many-body State representation of the molecule. The effects of intramolecular Coulomb interaction on conductance and luminescence spe...

Yousoo Kim - One of the best experts on this subject based on the ideXlab platform.

  • many body State Description of single molecule electroluminescence driven by a scanning tunneling microscope
    Nano Letters, 2019
    Co-Authors: Kuniyuki Miwa, Hiroshi Imada, Miyabi Imaiimada, Kensuke Kimura, Michael Galperin, Yousoo Kim
    Abstract:

    Electron transport and optical properties of a single molecule in contact with conductive materials have attracted considerable attention because of their scientific importance and potential applications. With the recent progress in experimental techniques, especially by virtue of scanning tunneling microscope (STM)-induced light emission, where the tunneling current of the STM is used as an atomic-scale source for induction of light emission from a single molecule, it has become possible to investigate single-molecule properties at subnanometer spatial resolution. Despite extensive experimental studies, the microscopic mechanism of electronic excitation of a single molecule in STM-induced light emission has yet to be clarified. Here we present a formulation of single-molecule electroluminescence driven by electron transfer between a molecule and metal electrodes based on a many-body State representation of the molecule. The effects of intramolecular Coulomb interaction on conductance and luminescence spectra are investigated using the nonequilibrium Hubbard Green's function technique combined with first-principles calculations. We compare simulation results with experimental data and find that the intramolecular Coulomb interaction is crucial for reproducing recent experiments for a single phthalocyanine molecule. The developed theory provides a unified Description of the electron transport and optical properties of a single molecule in contact with metal electrodes driven out of equilibrium, and thereby, it contributes to a microscopic understanding of optoelectronic conversion in single molecules on solid surfaces and in nanometer-scale junctions.