Visualizing Electric and Magnetic Field Coupling in Au-Nanorod Trimer Structures via Stimulated Electron Energy Gain and Cathodoluminescence Spectroscopy: Implications for Meta-Atom Imaging

David A. Garfinkel; Vasudevan Iyer; Robyn Seils; Grace Pakeltis; Marc R. Bourgeois; Andrew W. Rossi; Clay Klein; Benjamin J. Lawrie; David J. Masiello; Philip D. Rack

doi:10.1021/acsanm.1c03171

Visualizing Electric and Magnetic Field Coupling in Au-Nanorod Trimer Structures via Stimulated Electron Energy Gain and Cathodoluminescence Spectroscopy: Implications for Meta-Atom Imaging

David A. Garfinkel, Vasudevan Iyer, Robyn Seils, Grace Pakeltis, Marc R. Bourgeois, Andrew W. Rossi, Clay Klein, Benjamin J. Lawrie, David J. Masiello, Philip D. Rack

Quantum Heterostructures

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2 Scopus citations

Abstract

Trimer meta-atoms composed of three gold rods in an equilateral triangular geometry were fabricated, and their near-field plasmonic responses were characterized via electron energy loss (EEL), cathodoluminescence (CL), and stimulated electron energy loss/gain (sEEL/sEEG) spectroscopy. The trimer structure hybridizes into a low-energy mode with all three rods coupling in-phase, which produces a circulating current and thus a magnetic field. The next highest-energy mode consists of two rods coupling out-of-phase and produces a net electric dipole. We investigate the near fields of hybridized magnetic and electric modes via EEL and CL and correlate their spectral characteristics and intensity maps. Then, by changing the length of the trimer rods, we tune the magnetic and electric modes to our laser energy and characterize the excited state via sEEL/sEEG spectroscopy. Exploration of the tilt dependence, relative to the optical source, of the two modes reveals that the electric mode sEEG intensity increases more than the expected sin²(θ) dependence of the optical electric field coupling (see the Supporting Information for a detailed description). After correcting for the tail of the close-proximity electric mode, we demonstrate sEEG via coupling of the magnetic component of the optical field to the magnetic meta-atoms, which has the expected cos²(θ) tilt dependence. This realization opens the possibility to explore the nanoscale excited-state near-field imaging of other magnetic meta-atom structures.

Original language	English
Pages (from-to)	1798-1807
Number of pages	10
Journal	ACS Applied Nano Materials
Volume	5
Issue number	2
DOIs	https://doi.org/10.1021/acsanm.1c03171
State	Published - Feb 25 2022

Funding

D.A.G., R.S., G.P., and P.D.R. acknowledge support from the National Science Foundation under grant NSF DMR 1709275. P.D.R. acknowledges that the laser delivery system was built by Tom Moore and Greg Magel at Waviks, Inc. and the system development is supported by NSF SBIR-1721719 and 1853201. Work at the University of Washington was supported by the U.S. National Science Foundation under Award CHE-1954393 (M.R.B., A.W.R., and D.J.M.). All the authors acknowledge that the nanofabrication, high-energy resolution EELS measurements, and CL were conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

Funders	Funder number
National Science Foundation	NSF DMR 1709275, SBIR-1721719, CHE-1954393, 1853201

Keywords

electron energy spectroscopy
magnetic dipole
meta-atom
plasmonic
trimer

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10.1021/acsanm.1c03171

Cite this

Garfinkel, D. A., Iyer, V., Seils, R., Pakeltis, G., Bourgeois, M. R., Rossi, A. W., Klein, C., Lawrie, B. J., Masiello, D. J., & Rack, P. D. (2022). Visualizing Electric and Magnetic Field Coupling in Au-Nanorod Trimer Structures via Stimulated Electron Energy Gain and Cathodoluminescence Spectroscopy: Implications for Meta-Atom Imaging. ACS Applied Nano Materials, 5(2), 1798-1807. https://doi.org/10.1021/acsanm.1c03171

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title = "Visualizing Electric and Magnetic Field Coupling in Au-Nanorod Trimer Structures via Stimulated Electron Energy Gain and Cathodoluminescence Spectroscopy: Implications for Meta-Atom Imaging",

abstract = "Trimer meta-atoms composed of three gold rods in an equilateral triangular geometry were fabricated, and their near-field plasmonic responses were characterized via electron energy loss (EEL), cathodoluminescence (CL), and stimulated electron energy loss/gain (sEEL/sEEG) spectroscopy. The trimer structure hybridizes into a low-energy mode with all three rods coupling in-phase, which produces a circulating current and thus a magnetic field. The next highest-energy mode consists of two rods coupling out-of-phase and produces a net electric dipole. We investigate the near fields of hybridized magnetic and electric modes via EEL and CL and correlate their spectral characteristics and intensity maps. Then, by changing the length of the trimer rods, we tune the magnetic and electric modes to our laser energy and characterize the excited state via sEEL/sEEG spectroscopy. Exploration of the tilt dependence, relative to the optical source, of the two modes reveals that the electric mode sEEG intensity increases more than the expected sin2(θ) dependence of the optical electric field coupling (see the Supporting Information for a detailed description). After correcting for the tail of the close-proximity electric mode, we demonstrate sEEG via coupling of the magnetic component of the optical field to the magnetic meta-atoms, which has the expected cos2(θ) tilt dependence. This realization opens the possibility to explore the nanoscale excited-state near-field imaging of other magnetic meta-atom structures.",

keywords = "electron energy spectroscopy, magnetic dipole, meta-atom, plasmonic, trimer",

author = "Garfinkel, {David A.} and Vasudevan Iyer and Robyn Seils and Grace Pakeltis and Bourgeois, {Marc R.} and Rossi, {Andrew W.} and Clay Klein and Lawrie, {Benjamin J.} and Masiello, {David J.} and Rack, {Philip D.}",

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Garfinkel, DA, Iyer, V, Seils, R, Pakeltis, G, Bourgeois, MR, Rossi, AW, Klein, C, Lawrie, BJ, Masiello, DJ & Rack, PD 2022, 'Visualizing Electric and Magnetic Field Coupling in Au-Nanorod Trimer Structures via Stimulated Electron Energy Gain and Cathodoluminescence Spectroscopy: Implications for Meta-Atom Imaging', ACS Applied Nano Materials, vol. 5, no. 2, pp. 1798-1807. https://doi.org/10.1021/acsanm.1c03171

Visualizing Electric and Magnetic Field Coupling in Au-Nanorod Trimer Structures via Stimulated Electron Energy Gain and Cathodoluminescence Spectroscopy: Implications for Meta-Atom Imaging. / Garfinkel, David A.; Iyer, Vasudevan; Seils, Robyn et al.
In: ACS Applied Nano Materials, Vol. 5, No. 2, 25.02.2022, p. 1798-1807.

Research output: Contribution to journal › Article › peer-review

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T2 - Implications for Meta-Atom Imaging

AU - Garfinkel, David A.

AU - Iyer, Vasudevan

AU - Seils, Robyn

AU - Pakeltis, Grace

AU - Bourgeois, Marc R.

AU - Rossi, Andrew W.

AU - Klein, Clay

AU - Lawrie, Benjamin J.

AU - Masiello, David J.

AU - Rack, Philip D.

PY - 2022/2/25

Y1 - 2022/2/25

N2 - Trimer meta-atoms composed of three gold rods in an equilateral triangular geometry were fabricated, and their near-field plasmonic responses were characterized via electron energy loss (EEL), cathodoluminescence (CL), and stimulated electron energy loss/gain (sEEL/sEEG) spectroscopy. The trimer structure hybridizes into a low-energy mode with all three rods coupling in-phase, which produces a circulating current and thus a magnetic field. The next highest-energy mode consists of two rods coupling out-of-phase and produces a net electric dipole. We investigate the near fields of hybridized magnetic and electric modes via EEL and CL and correlate their spectral characteristics and intensity maps. Then, by changing the length of the trimer rods, we tune the magnetic and electric modes to our laser energy and characterize the excited state via sEEL/sEEG spectroscopy. Exploration of the tilt dependence, relative to the optical source, of the two modes reveals that the electric mode sEEG intensity increases more than the expected sin2(θ) dependence of the optical electric field coupling (see the Supporting Information for a detailed description). After correcting for the tail of the close-proximity electric mode, we demonstrate sEEG via coupling of the magnetic component of the optical field to the magnetic meta-atoms, which has the expected cos2(θ) tilt dependence. This realization opens the possibility to explore the nanoscale excited-state near-field imaging of other magnetic meta-atom structures.

AB - Trimer meta-atoms composed of three gold rods in an equilateral triangular geometry were fabricated, and their near-field plasmonic responses were characterized via electron energy loss (EEL), cathodoluminescence (CL), and stimulated electron energy loss/gain (sEEL/sEEG) spectroscopy. The trimer structure hybridizes into a low-energy mode with all three rods coupling in-phase, which produces a circulating current and thus a magnetic field. The next highest-energy mode consists of two rods coupling out-of-phase and produces a net electric dipole. We investigate the near fields of hybridized magnetic and electric modes via EEL and CL and correlate their spectral characteristics and intensity maps. Then, by changing the length of the trimer rods, we tune the magnetic and electric modes to our laser energy and characterize the excited state via sEEL/sEEG spectroscopy. Exploration of the tilt dependence, relative to the optical source, of the two modes reveals that the electric mode sEEG intensity increases more than the expected sin2(θ) dependence of the optical electric field coupling (see the Supporting Information for a detailed description). After correcting for the tail of the close-proximity electric mode, we demonstrate sEEG via coupling of the magnetic component of the optical field to the magnetic meta-atoms, which has the expected cos2(θ) tilt dependence. This realization opens the possibility to explore the nanoscale excited-state near-field imaging of other magnetic meta-atom structures.

KW - electron energy spectroscopy

KW - magnetic dipole

KW - meta-atom

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Visualizing Electric and Magnetic Field Coupling in Au-Nanorod Trimer Structures via Stimulated Electron Energy Gain and Cathodoluminescence Spectroscopy: Implications for Meta-Atom Imaging

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