Open AccessHigh spatial and energy resolution electron energy loss spectroscopy of the magnetic and electric excitations in plasmonic nanorod oligomers
Author(s) -
Grace Pakeltis,
Enzo Rotunno,
Siamak Khorassani,
David A. Garfinkel,
Robyn Collette,
Claire A. West,
Scott T. Retterer,
Juan Carlos Idrobo,
David J. Masiello,
Philip D. Rack
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.416046
Subject(s) - plasmon , optics , electron energy loss spectroscopy , nanorod , dipole , electron , materials science , magnetic dipole , molecular physics , spectroscopy , physics , transmission electron microscopy , nanotechnology , quantum mechanics
We leverage the high spatial and energy resolution of monochromated aberration-corrected scanning transmission electron microscopy to study the hybridization of cyclic assemblies of plasmonic gold nanorods. Detailed experiments and simulations elucidate the hybridization of the coupled long-axis dipole modes into collective magnetic and electric dipole plasmon resonances. We resolve the magnetic dipole mode in these closed loop oligomers with electron energy loss spectroscopy and confirm the mode assignment with its characteristic spectrum image. The energy splitting of the magnetic mode and antibonding modes increases with the number of polygon edges (n). For the n=3-6 oligomers studied, optical simulations using normal incidence and s-polarized oblique incidence show the respective electric and magnetic modes' extinction efficiencies are maximized in the n=4 arrangement.