High spatial and energy resolution electron energy loss spectroscopy of the magnetic and electric excitations in plasmonic nanorod oligomers.

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.

[1]  S. Reich,et al.  Selection Rules for Structured Light in Nanooligomers and Other Nanosystems , 2020, 2102.07649.

[2]  J. Idrobo,et al.  Infrared plasmonics: STEM-EELS characterization of Fabry-Pérot resonance damping in gold nanowires , 2020 .

[3]  Stephen J. Bauman,et al.  Dynamic Plasmonic Pixels. , 2019, ACS nano.

[4]  Ottawa,et al.  Orbital Angular Momentum and Energy Loss Characterization of Plasmonic Excitations in Metallic Nanostructures in TEM , 2018, ACS Photonics.

[5]  Ashour M. Ahmed,et al.  Plasmonic hybridization between two metallic nanorods , 2018, Optik.

[6]  J. Hachtel,et al.  Exploring the capabilities of monochromated electron energy loss spectroscopy in the infrared regime , 2018, Scientific Reports.

[7]  J. Verbeeck,et al.  Probing the symmetry of the potential of localized surface plasmon resonances with phase-shaped electron beams , 2016, Nature Communications.

[8]  Jacob A. Busche,et al.  STEM/EELS Imaging of Magnetic Hybridization in Symmetric and Symmetry-Broken Plasmon Oligomer Dimers and All-Magnetic Fano Interference. , 2016, Nano letters.

[9]  Charles R Cherqui,et al.  Imaging Plasmon Hybridization in Metal Nanoparticle Aggregates with Electron Energy-Loss Spectroscopy , 2016 .

[10]  M. Lipson,et al.  Broadband mid-infrared frequency comb generation in a Si3N4 microresonator , 2015, 2015 Conference on Lasers and Electro-Optics (CLEO).

[11]  G. Haran,et al.  The simplest plasmonic molecules: Metal nanoparticle dimers and trimers , 2014 .

[12]  Andrea Alù,et al.  The quest for optical magnetism: from split-ring resonators to plasmonic nanoparticles and nanoclusters , 2014 .

[13]  P. Batson,et al.  Vibrational spectroscopy in the electron microscope , 2014, Nature.

[14]  H. Ditlbacher,et al.  Morphing a Plasmonic Nanodisk into a Nanotriangle , 2014, Nano letters.

[15]  Andrea Alu,et al.  A subwavelength plasmonic metamolecule exhibiting magnetic-based optical Fano resonance , 2013, CLEO: 2013.

[16]  M. Hentschel,et al.  Plasmonic oligomers in cylindrical vector light beams , 2013, Beilstein journal of nanotechnology.

[17]  R. Olmon,et al.  Optical dielectric function of gold , 2012 .

[18]  J. Camden,et al.  Characterization of the electron- and photon-driven plasmonic excitations of metal nanorods. , 2012, ACS nano.

[19]  M. Kociak,et al.  Modal decompositions of the local electromagnetic density of states and spatially resolved electron energy loss probability in terms of geometric modes , 2012 .

[20]  Ulrich Hohenester,et al.  MNPBEM - A Matlab toolbox for the simulation of plasmonic nanoparticles , 2011, Comput. Phys. Commun..

[21]  Xiang Zhang,et al.  Metamaterials: a new frontier of science and technology. , 2011, Chemical Society reviews.

[22]  Zhensen Wu,et al.  Analysis of electromagnetic scattering by uniaxial anisotropic bispheres. , 2011, Journal of the Optical Society of America. A, Optics, image science, and vision.

[23]  Harald Giessen,et al.  Coupling effects in optical metamaterials. , 2010, Angewandte Chemie.

[24]  Federico Capasso,et al.  Self-Assembled Plasmonic Nanoparticle Clusters , 2010, Science.

[25]  F. D. Abajo,et al.  Optical excitations in electron microscopy , 2009, 0903.1669.

[26]  Peter Nordlander,et al.  Plasmon modes of nanosphere trimers and quadrumers. , 2006, The journal of physical chemistry. B.

[27]  E. N. Economou,et al.  Saturation of the magnetic response of split-ring resonators at optical frequencies. , 2005, Physical review letters.

[28]  B. Draine,et al.  Discrete-Dipole Approximation For Scattering Calculations , 1994 .