The Experts below are selected from a list of 101367 Experts worldwide ranked by ideXlab platform
George C Schatz - One of the best experts on this subject based on the ideXlab platform.
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combined quantum mechanics tddft and classical Electrodynamics mie theory methods for calculating surface enhanced raman and hyper raman spectra
Journal of Physical Chemistry A, 2012Co-Authors: Jonathan M Mullin, Nicholas Valley, Martin G Blaber, George C SchatzAbstract:Multiscale models that combine quantum mechanics and classical Electrodynamics are presented, which allow for the evaluation of surface-enhanced Raman (SERS) and hyper-Raman scattering spectra (SEHRS) for both chemical (CHEM) and electrodynamic (EM) enhancement mechanisms. In these models, time-dependent density functional theory (TDDFT) for a system consisting of the adsorbed molecule and a metal cluster fragment of the metal particle is coupled to Mie theory for the metal particle, with the surface of the cluster being overlaid with the surface of the metal particle. In model A, the electromagnetic enhancement from plasmon-excitation of the metal particle is combined with the chemical enhancement associated with a static treatment of the molecule–metal structure to determine overall spectra. In model B, the frequency dependence of the Raman spectrum of the isolated molecule is combined with the enhancements determined in model A to refine the enhancement estimate. An equivalent theory at the level of mo...
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dna linked metal nanosphere materials structural basis for the optical properties
Journal of Physical Chemistry B, 2000Co-Authors: Anne A Lazarides, George C SchatzAbstract:The structural basis for the aggregation-induced optical properties of colloidal gold nanosphere aggregates is examined by means of Electrodynamics calculations. Recently developed methods for calculating the electrodynamic response of aggregates composed of large numbers of small metal nanospheres in a dielectric medium are used to determine the optical changes associated with the formation of spherical aggregates. The calculations use accurate nanoparticle polarizabilities determined from Mie theory, an iterative conjugate-gradient solution algorithm, and fast-Fourier transform methods for efficient solution of the electrodynamic interacting nanoparticle equations. The UV extinction lowering and the shifting and broadening of the visible plasmon peak observed experimentally in solutions of DNA-linked gold nanospheres are explained as the collective electromagnetic response of thousands of nanoparticles.
E. A. Kihn - One of the best experts on this subject based on the ideXlab platform.
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Polar cap index comparisons with AMIE cross polar cap potential, electric field, and polar cap area
Geophysical Research Letters, 2004Co-Authors: Andrew Ridley, E. A. KihnAbstract:[1] The polar cap index (PCI) has been shown to be quite useful as an index of the electrodynamic processes within the high-latitude ionosphere. Here we use between 150 and 180 magnetometers to model the high-latitude Electrodynamics with the assimilative mapping of ionospheric Electrodynamics (AMIE) technique for all of 1997–2001. We compare AMIE calculations of the cross polar cap potential (CPCP), polar cap electric field, and polar cap area to the Northern PCI and the existing PCI-based relationships for these quantities. We find that the existing PCI estimates underestimate all of the AMIE derived quantities. The PCI is best correlated with the CPCP, while it correlates least with the polar cap electric field. In addition, there is a seasonal effect in the relationship between all AMIE quantities and the PCI. It is most pronounced in the electric field. The polar cap area is shown to have a linear fit in the summer and an asymptotic fit in the winter. These differences indicate that there may be a conductance difference in the techniques. We derive new relationships between the Northern PCI and the AMIE derived polar cap area, CPCP, and polar cap electric field which include the seasonal dependence.
Andrew Ridley - One of the best experts on this subject based on the ideXlab platform.
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Polar cap index comparisons with AMIE cross polar cap potential, electric field, and polar cap area
Geophysical Research Letters, 2004Co-Authors: Andrew Ridley, E. A. KihnAbstract:[1] The polar cap index (PCI) has been shown to be quite useful as an index of the electrodynamic processes within the high-latitude ionosphere. Here we use between 150 and 180 magnetometers to model the high-latitude Electrodynamics with the assimilative mapping of ionospheric Electrodynamics (AMIE) technique for all of 1997–2001. We compare AMIE calculations of the cross polar cap potential (CPCP), polar cap electric field, and polar cap area to the Northern PCI and the existing PCI-based relationships for these quantities. We find that the existing PCI estimates underestimate all of the AMIE derived quantities. The PCI is best correlated with the CPCP, while it correlates least with the polar cap electric field. In addition, there is a seasonal effect in the relationship between all AMIE quantities and the PCI. It is most pronounced in the electric field. The polar cap area is shown to have a linear fit in the summer and an asymptotic fit in the winter. These differences indicate that there may be a conductance difference in the techniques. We derive new relationships between the Northern PCI and the AMIE derived polar cap area, CPCP, and polar cap electric field which include the seasonal dependence.
Jin Young Kim - One of the best experts on this subject based on the ideXlab platform.
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bending of electromagnetic wave in an ultra strong magnetic field
Journal of Cosmology and Astroparticle Physics, 2012Co-Authors: Jin Young KimAbstract:We consider the bending of light by nonlinear Electrodynamics when the magnetic field B exceeds the critical value Bc = m2c2/e = 4.4 × 109T. Using the index of refraction derived from the analytic series representation in one-loop effective action of QED, we found the trajectory and the bending angle of light in geometric optics. The angle bent by ultra-strong magnetic field of magnetar was estimated and compared with the gravitational bending. The result may be useful in studying the lensing, birefringence, and other nonlinear quantum electrodynamic effects above Bc.
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bending of electromagnetic wave in an ultra strong magnetic field
arXiv: High Energy Physics - Phenomenology, 2012Co-Authors: Jin Young KimAbstract:We consider the bending of light by nonlinear Electrodynamics when the magnetic field $B$ exceeds the critical value $B_{\rm c}$. Using the index of refraction derived from the analytic series representation in one-loop effective action of QED, we found the trajectory and the bending angle of light in geometric optics. The angle bent by ultra-strong magnetic field of magnetar was estimated and compared with the gravitational bending. The result may be useful in studying the lensing, birefringence, and other nonlinear quantum electrodynamic effects above $B_{\rm c}$.
Jonathan M Mullin - One of the best experts on this subject based on the ideXlab platform.
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combined quantum mechanics tddft and classical Electrodynamics mie theory methods for calculating surface enhanced raman and hyper raman spectra
Journal of Physical Chemistry A, 2012Co-Authors: Jonathan M Mullin, Nicholas Valley, Martin G Blaber, George C SchatzAbstract:Multiscale models that combine quantum mechanics and classical Electrodynamics are presented, which allow for the evaluation of surface-enhanced Raman (SERS) and hyper-Raman scattering spectra (SEHRS) for both chemical (CHEM) and electrodynamic (EM) enhancement mechanisms. In these models, time-dependent density functional theory (TDDFT) for a system consisting of the adsorbed molecule and a metal cluster fragment of the metal particle is coupled to Mie theory for the metal particle, with the surface of the cluster being overlaid with the surface of the metal particle. In model A, the electromagnetic enhancement from plasmon-excitation of the metal particle is combined with the chemical enhancement associated with a static treatment of the molecule–metal structure to determine overall spectra. In model B, the frequency dependence of the Raman spectrum of the isolated molecule is combined with the enhancements determined in model A to refine the enhancement estimate. An equivalent theory at the level of mo...
