Seminar: "A Taxonomy of the Magneto-Optical
Responses of Cyclic Plasmon-Supporting Metal Oligomers" by David J.
Masiello
Thursday, November 6, 2014 11:00 AM to 12:00 PM
CREOL Room 103
CREOL Room 103
David J. Masiello, Assistant Professor
Department of Chemistry, University of Washington
Abstract:
The optical-frequency magnetic and electric properties of
cyclic plasmon-supporting metal nanoparticle oligomers are explored through a
combination of scanning transmission electron microscopy (STEM)/electron
energy-loss spectroscopy (EELS) simulation and first-principles theory. A
tight-binding type model is introduced to explore the rich hybridization
physics in these plasmonic systems and tested with full-wave numerical
electrodynamics simulations of the STEM electron probe. Building from a
microscopic electric model, connection is made at the macroscopic level between
the hybridization of localized magnetic moments into delocalized magnetic
plasmons of controllable magnetic order and the mixing of atomic p_z orbitals
into delocalized pi molecular orbitals of varying nodal structure spanning the
molecule. It is found that the STEM electrons are uniquely capable of exciting
all of the different hybridized eigenmodes of the nanoparticle
assembly---including multipolar closed-loop ferromagnetic and antiferromagnetic
plasmons, giant electric dipole resonances, and radial breathing modes---by
raster scanning the beam to the appropriate position. Comparison to plane-wave
light scattering and cathodoluminescence (CL) spectroscopy is made. The
presented work provides a unified understanding of the complete plasmon
eigenstructure of such oligomer systems as well as of the excitation conditions
necessary to probe each mode.
Biography:
David J. Masiello completed a B.S. degree in mathematics
from the University of Florida in 1999. He then joined the University of
Florida's Quantum Theory Project as a graduate student in chemical physics,
where, in 2004, he received the Ph.D. degree working under the tutelage of
Professor Yngve Öhrn. His dissertation work explored a nonperturbative
treatment of the interaction between molecules and the electromagnetic field,
accounting for the redistribution of energy not only between different internal
molecular degrees of freedom but also for its liberation to the dynamical
electromagnetic field. He then took two postdoctoral positions, one with
Prof. William P. Reinhardt at the University of Washington (2004-2006) and the
second with Professor George C. Schatz at Northwestern University
(2006-2009). Subsequently, David was hired back to the University of
Washington in 2010 where he is now an assistant professor in theoretical
chemistry. Currently, Professor Masiello's research focuses on the theoretical
understanding of a variety of nanoscale light-matter interactions involving the
excitation of surface plasmon resonances. Examples include electron
energy-loss spectroscopy, cathodoluminescence, thermo-plasmonics,
plasmon-enhanced catalysis, and plasmon-enhanced linear and nonlinear molecular
optical phenomena. As of Spring 2014, David is also a faculty member by
courtesy in the Physics and Applied Mathematics departments at UW.
For more information:
Dr. Leonid Glebov
407-823-6983
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