ELECTROMAGNETIC PROPERTIES OF SMALL SOLID STATE PARTICLES AND REALISTIC SURFACES.
Item
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Title
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ELECTROMAGNETIC PROPERTIES OF SMALL SOLID STATE PARTICLES AND REALISTIC SURFACES.
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Identifier
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AAI8302501
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identifier
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8302501
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Creator
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DAS, PURNA CHANDRA.
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Contributor
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Joel I. Gersten
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Date
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1983
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Condensed Matter
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Abstract
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We study the electromagnetic properties of small solid state particles. In particular the origin and consequences of spontaneous electric dipole moments in small particles of diameter ranging from 10-1000 (ANGSTROM) are considered. Theoretical analysis of such particles with or without nearby molecules is done and their surface effects are extracted. Various mechanisms promoting the dipole moments are considered (dispersion dipole due to nearby molecules, binary composite structures, and asymmetric homogeneous structures). The study is basically divided into two parts--homogeneous systems and inhomogeneous systems. Under homogeneous systems we evaluate the dipole moment of a hemispherical jellium shape. Under inhomogeneous systems we evaluate the dipole moment of an atom near a spheroid and the dipole moment of a bimetallic spheroid.;Rough surfaces have unusual optical properties. We model roughness as a spheroidal bump protruding out of a flat plane surface and study the surface shape (electromagnetic) resonances of such a bumpy surface. The shape resonances are based on the fact that there are localized states associated with the (vibrating) bumps, which can couple to the delocalized collective (electronic or ionic) excitations of the underlying substrate. Our goal is to study, and determine the frequencies and widths of these surface shape resonances.;The study of a rough surface and its neighborhood in various experimental situations by electron loss spectroscopy is a rapidly growing field. So we consider inelastic electron scattering from isolated metal spheres. The electron energy loss to be considered arises from the excitation of plasmons associated with the sphere. Expressions for the scattering cross section and for the radiative scattering are derived.;Finally we use the fact, that there exists a set of shape resonances for a bumpy surface to investigate the effects of the presence of a substrate on a molecule undergoing photochemical reaction. The energy accumulation by the molecule, as required in photochemical reaction, would be hindered if there were damping mechanisms such as are associated with the shape resonances. We therefore investigate the effects of the substrate on photochemical reaction taking into account the surface shape resonances. Expressions of the cross section for photochemistry and radiative cross section of the molecule are derived. We shall see if the enhancement of photochemical reactions occurs due to the enhanced local field near a rough surface.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Physics
