Optical scattering from nanoparticle aggregates

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Title: Optical scattering from nanoparticle aggregates
Author: Travis, Kort Alan
Abstract: Nanometer -scale particles of the noble metals have been used for decades as contrast enhancement agents in electron microscopy . Over the past several years it has been demonstrated that these particles also function as excellent contrast agents for optical imaging techniques . The resonant optical scattering they exhibit enables scattering cross sections that may be many orders of magnitude greater than the analogous efficiency factor for fluorescent dye molecules . Biologically relevant labeling with nanoparticles generally results in aggregates containing a few to several tens of particles . The electrodynamic coupling between particles in these aggregates produces observable shifts in the resonance -scattering spectrum . This dissertation provides a theoretical analysis of the scattering from nanoparticle aggregates . The key objectives are to describe this scattering behavior qualitatively and to provide numerical codes usable for modeling its application to biomedical engineering . Considerations of the lowest -order dipole -dipole coupling lead to simple qualitative predictions of the behavior of the spectral properties of the optical cross sections as they depend on number of particles , inter -particle spacing , and aggregate aspect ratio . More comprehensive analysis using the multiple -particle T -matrix formalism allows the elaboration of more subtle cross -section spectral features depending on the interactions of the electrodynamic collective -modes of the aggregate , of individual -particle modes , and of modes associated with groups of particles within the aggregate sub -structure . In combination these analyses and the supporting numerical code -base provide a unified electrodynamic approach which facilitates interpretation of experimental cross section spectra , guides the design of new biophysical experiments using nanoparticle aggregates , and enables optimal fabrication of nanoparticle structures for biophysical applications .
URI: http : / /hdl .handle .net /2152 /ETD -UT -2010 -12 -2247
Date: 2011-02-09

Citation

Optical scattering from nanoparticle aggregates. Doctoral dissertation, University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /ETD -UT -2010 -12 -2247 .

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