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Janne Pesonen - One of the best experts on this subject based on the ideXlab platform.

  • constrained Molecular Vibration rotation hamiltonians contravariant metric tensor
    Journal of Chemical Physics, 2013
    Co-Authors: Janne Pesonen
    Abstract:

    Here, I present a practical recipe for obtaining contravariant Vibration-rotation metric tensors, and thus the kinetic energy operators, when some degrees of freedom are constrained rigidly. An element of the contravariant metric tensor is obtained as a sum of dot products of contravariant measuring vectors, which are obtained from their unconstrained counterparts by adding a frozen mode correction. The present method applies in principle for any choice of shape coordinates and a body-frame for which the contravariant measuring vectors can be evaluated. In contrast to the existing methods, the present method does not involve evaluation of covariant metric tensors, matrix inversions, chain rules of derivation, or numerical differentiation. It is applied in the sequel paper [L. Partanen, J. Pesonen, E. Sjoholm, and L. Halonen, J. Chem. Phys. 139, 144311 (2013)] to study the effects of several different approximations to the kinetic energy operator, when the two large-amplitude OH-torsional motions in H2SO4 ...

  • constrained Molecular Vibration rotation hamiltonians contravariant metric tensor
    Journal of Chemical Physics, 2013
    Co-Authors: Janne Pesonen
    Abstract:

    Here, I present a practical recipe for obtaining contravariant Vibration-rotation metric tensors, and thus the kinetic energy operators, when some degrees of freedom are constrained rigidly. An element of the contravariant metric tensor is obtained as a sum of dot products of contravariant measuring vectors, which are obtained from their unconstrained counterparts by adding a frozen mode correction. The present method applies in principle for any choice of shape coordinates and a body-frame for which the contravariant measuring vectors can be evaluated. In contrast to the existing methods, the present method does not involve evaluation of covariant metric tensors, matrix inversions, chain rules of derivation, or numerical differentiation. It is applied in the sequel paper [L. Partanen, J. Pesonen, E. Sjoholm, and L. Halonen, J. Chem. Phys. 139, 144311 (2013)] to study the effects of several different approximations to the kinetic energy operator, when the two large-amplitude OH-torsional motions in H2SO4 are of interest.

Tobias J Kippenberg - One of the best experts on this subject based on the ideXlab platform.

  • Molecular cavity optomechanics as a theory of plasmon enhanced raman scattering
    Nature Nanotechnology, 2016
    Co-Authors: Philippe Roelli, Christophe Galland, Nicolas Piro, Tobias J Kippenberg
    Abstract:

    The exceptional enhancement of Raman scattering by localized plasmonic resonances in the near field of metallic nanoparticles, surfaces or tips (SERS, TERS) has enabled spectroscopic fingerprinting down to the single molecule level. The conventional explanation attributes the enhancement to the subwavelength confinement of the electromagnetic field near nanoantennas. Here, we introduce a new model that also accounts for the dynamical nature of the plasmon-molecule interaction. We thereby reveal an enhancement mechanism not considered before: dynamical backaction amplification of Molecular Vibrations. We first map the system onto the canonical Hamiltonian of cavity optomechanics, in which the Molecular Vibration and the plasmon are parametrically coupled. We express the vacuum optomechanical coupling rate for individual molecules in plasmonic 'hot-spots' in terms of the Vibrational mode's Raman activity and find it to be orders of magnitude larger than for microfabricated optomechanical systems. Remarkably, the frequency of commonly studied Molecular Vibrations can be comparable to or larger than the plasmon's decay rate. Together, these considerations predict that an excitation laser blue-detuned from the plasmon resonance can parametrically amplify the Molecular Vibration, leading to a nonlinear enhancement of Raman emission that is not predicted by the conventional theory. Our optomechanical approach recovers known results, provides a quantitative framework for the calculation of cross-sections, and enables the design of novel systems that leverage dynamical backaction to achieve additional, mode-selective enhancements. It also provides a quantum mechanical framework to analyse plasmon-Vibrational interactions in terms of Molecular quantum optomechanics.

  • Molecular cavity optomechanics as a theory of plasmon enhanced raman scattering
    Nature Nanotechnology, 2016
    Co-Authors: Philippe Roelli, Christophe Galland, Nicolas Piro, Tobias J Kippenberg
    Abstract:

    The exceptional enhancement of Raman scattering by localized plasmonic resonances in the near field of metallic nanoparticles, surfaces or tips (SERS, TERS) has enabled spectroscopic fingerprinting down to the single molecule level. The conventional explanation attributes the enhancement to the subwavelength confinement of the electromagnetic field near nanoantennas. Here, we introduce a new model that also accounts for the dynamical nature of the plasmon–molecule interaction. We thereby reveal an enhancement mechanism not considered before: dynamical backaction amplification of Molecular Vibrations. We first map the system onto the canonical Hamiltonian of cavity optomechanics, in which the Molecular Vibration and the plasmon are parametrically coupled. We express the vacuum optomechanical coupling rate for individual molecules in plasmonic ‘hot-spots’ in terms of the Vibrational mode's Raman activity and find it to be orders of magnitude larger than for microfabricated optomechanical systems. Remarkably, the frequency of commonly studied Molecular Vibrations can be comparable to or larger than the plasmon's decay rate. Together, these considerations predict that an excitation laser blue-detuned from the plasmon resonance can parametrically amplify the Molecular Vibration, leading to a nonlinear enhancement of Raman emission that is not predicted by the conventional theory. Our optomechanical approach recovers known results, provides a quantitative framework for the calculation of cross-sections, and enables the design of novel systems that leverage dynamical backaction to achieve additional, mode-selective enhancements. It also provides a quantum mechanical framework to analyse plasmon–Vibrational interactions in terms of Molecular quantum optomechanics. A cavity optomechanics model accounting for the intrinsic dynamics of the interaction between plasmons and Molecular Vibrations reveals a parametric amplification mechanism that may provide an explanation for features recently observed in nonlinear Raman spectroscopy experiments.

Philippe Roelli - One of the best experts on this subject based on the ideXlab platform.

  • Molecular cavity optomechanics as a theory of plasmon enhanced raman scattering
    Nature Nanotechnology, 2016
    Co-Authors: Philippe Roelli, Christophe Galland, Nicolas Piro, Tobias J Kippenberg
    Abstract:

    The exceptional enhancement of Raman scattering by localized plasmonic resonances in the near field of metallic nanoparticles, surfaces or tips (SERS, TERS) has enabled spectroscopic fingerprinting down to the single molecule level. The conventional explanation attributes the enhancement to the subwavelength confinement of the electromagnetic field near nanoantennas. Here, we introduce a new model that also accounts for the dynamical nature of the plasmon-molecule interaction. We thereby reveal an enhancement mechanism not considered before: dynamical backaction amplification of Molecular Vibrations. We first map the system onto the canonical Hamiltonian of cavity optomechanics, in which the Molecular Vibration and the plasmon are parametrically coupled. We express the vacuum optomechanical coupling rate for individual molecules in plasmonic 'hot-spots' in terms of the Vibrational mode's Raman activity and find it to be orders of magnitude larger than for microfabricated optomechanical systems. Remarkably, the frequency of commonly studied Molecular Vibrations can be comparable to or larger than the plasmon's decay rate. Together, these considerations predict that an excitation laser blue-detuned from the plasmon resonance can parametrically amplify the Molecular Vibration, leading to a nonlinear enhancement of Raman emission that is not predicted by the conventional theory. Our optomechanical approach recovers known results, provides a quantitative framework for the calculation of cross-sections, and enables the design of novel systems that leverage dynamical backaction to achieve additional, mode-selective enhancements. It also provides a quantum mechanical framework to analyse plasmon-Vibrational interactions in terms of Molecular quantum optomechanics.

  • Molecular cavity optomechanics as a theory of plasmon enhanced raman scattering
    Nature Nanotechnology, 2016
    Co-Authors: Philippe Roelli, Christophe Galland, Nicolas Piro, Tobias J Kippenberg
    Abstract:

    The exceptional enhancement of Raman scattering by localized plasmonic resonances in the near field of metallic nanoparticles, surfaces or tips (SERS, TERS) has enabled spectroscopic fingerprinting down to the single molecule level. The conventional explanation attributes the enhancement to the subwavelength confinement of the electromagnetic field near nanoantennas. Here, we introduce a new model that also accounts for the dynamical nature of the plasmon–molecule interaction. We thereby reveal an enhancement mechanism not considered before: dynamical backaction amplification of Molecular Vibrations. We first map the system onto the canonical Hamiltonian of cavity optomechanics, in which the Molecular Vibration and the plasmon are parametrically coupled. We express the vacuum optomechanical coupling rate for individual molecules in plasmonic ‘hot-spots’ in terms of the Vibrational mode's Raman activity and find it to be orders of magnitude larger than for microfabricated optomechanical systems. Remarkably, the frequency of commonly studied Molecular Vibrations can be comparable to or larger than the plasmon's decay rate. Together, these considerations predict that an excitation laser blue-detuned from the plasmon resonance can parametrically amplify the Molecular Vibration, leading to a nonlinear enhancement of Raman emission that is not predicted by the conventional theory. Our optomechanical approach recovers known results, provides a quantitative framework for the calculation of cross-sections, and enables the design of novel systems that leverage dynamical backaction to achieve additional, mode-selective enhancements. It also provides a quantum mechanical framework to analyse plasmon–Vibrational interactions in terms of Molecular quantum optomechanics. A cavity optomechanics model accounting for the intrinsic dynamics of the interaction between plasmons and Molecular Vibrations reveals a parametric amplification mechanism that may provide an explanation for features recently observed in nonlinear Raman spectroscopy experiments.

Satoshi Kawata - One of the best experts on this subject based on the ideXlab platform.

Zhiwei Huang - One of the best experts on this subject based on the ideXlab platform.

  • heterodyne polarization coherent anti stokes raman scattering microscopy
    Applied Physics Letters, 2008
    Co-Authors: Wei Zheng, Zhiwei Huang
    Abstract:

    We develop a heterodyne-detected polarization coherent anti-Stokes Raman scattering (HP-CARS) microscopy for high sensitive and high contrast Molecular Vibration imaging. The HP-CARS technique, which utilizes interference of the weak resonant CARS signal and the relatively intense local oscillator field generated simultaneously within the same focal excitation volume of the sample for optical heterodyne detection, yields an approximately sevenfold improvement in Vibrational contrast compared with local oscillator CARS, while exhibiting a 12-fold amplification of the resonant signal compared with P-CARS. We demonstrate this method by imaging both 4.69μm polystyrene beads and unstained human epithelial cells in aqueous environments.