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Urbieta M, Barbry M, Koval P, Rivacoba A, Sánchez-Portal D, Aizpurua J, Zabala N. Footprints of atomic-scale features in plasmonic nanoparticles as revealed by electron energy loss spectroscopy. Phys Chem Chem Phys 2024; 26:14991-15004. [PMID: 38741574 DOI: 10.1039/d4cp01034e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
We present a first-principles theoretical study of the atomistic footprints in the valence electron energy loss spectroscopy (EELS) of nanometer-size metallic particles. Charge density maps of excited plasmons and EEL spectra for specific electron paths through a nanoparticle (Na380 atom cluster) are modeled using ab initio calculations within time-dependent density functional theory. Our findings unveil the atomic-scale sensitivity of EELS within this low-energy spectral range. Whereas localized surface plasmons (LSPs) are particularly sensitive to the atomistic structure of the surface probed by the electron beam, confined bulk plasmons (CBPs) reveal quantum size effects within the nanoparticle's volume. Moreover, we prove that classical local dielectric theories mimicking the atomistic structure of the nanoparticles reproduce the LSP trends observed in quantum calculations, but fall short in describing the CBP behavior observed under different electron trajectories.
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Affiliation(s)
- Mattin Urbieta
- Matematika Aplikatua Saila, Gipuzkoako Ingeniaritza Eskola (Eibarko Atala), University of the Basque Country UPV/EHU, 20018 Eibar, Spain.
- Centro de Física de Materiales CSIC - UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
| | - Marc Barbry
- Centro de Física de Materiales CSIC - UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
| | - Peter Koval
- Simune Atomistics S.L., Avenida de Tolosa 76, Donostia-San Sebastian 20018, Spain
| | - Alberto Rivacoba
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
| | - Daniel Sánchez-Portal
- Centro de Física de Materiales CSIC - UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
| | - Javier Aizpurua
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Department of Electricity and Electronics, FCT-ZTF, University of the Basque Country (UPV/EHU), Barrio Sarriena z/g, Leioa, Bizkaia 48940, Spain.
- Ikerbasque, Basque Foundation for Science, Bilbao, Bizkaia 48011, Spain
| | - Nerea Zabala
- Centro de Física de Materiales CSIC - UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, Gipuzkoa 20018, Spain
- Department of Electricity and Electronics, FCT-ZTF, University of the Basque Country (UPV/EHU), Barrio Sarriena z/g, Leioa, Bizkaia 48940, Spain.
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2
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Hauer R, Haberfehlner G, Kothleitner G, Kociak M, Hohenester U. Tomographic Reconstruction of Quasistatic Surface Polariton Fields. ACS PHOTONICS 2023; 10:185-196. [PMID: 36691424 PMCID: PMC9853846 DOI: 10.1021/acsphotonics.2c01431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Indexed: 06/17/2023]
Abstract
We theoretically investigate the tomographic reconstruction of the three-dimensional photonic environment of nanoparticles. As input for our reconstruction we use electron energy loss spectroscopy (EELS) maps for different rotation angles. We perform the tomographic reconstruction of surface polariton fields for smooth and rough nanorods and compare the reconstructed and simulated photonic local density of states, which are shown to be in very good agreement. Using these results, we critically examine the potential of our tomography scheme and discuss limitations and directions for future developments.
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Affiliation(s)
- Raphael Hauer
- Graz
Centre for Electron Microscopy, Steyrergasse 17, 8010Graz, Austria
| | | | - Gerald Kothleitner
- Graz
Centre for Electron Microscopy, Steyrergasse 17, 8010Graz, Austria
- Institute
for Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010Graz, Austria
| | - Mathieu Kociak
- Université
Paris-Saclay, CNRS, Laboratoire de Physique
des Solides, 91405Orsay, France
| | - Ulrich Hohenester
- Institute
of Physics, University of Graz, Universitätsplatz 5, 8010Graz, Austria
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3
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Bourgeois MR, Nixon AG, Chalifour M, Beutler EK, Masiello DJ. Polarization-Resolved Electron Energy Gain Nanospectroscopy With Phase-Structured Electron Beams. NANO LETTERS 2022; 22:7158-7165. [PMID: 36036765 DOI: 10.1021/acs.nanolett.2c02375] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Free-electron-based measurements in scanning transmission electron microscopes (STEMs) reveal valuable information on the broadband spectral responses of nanoscale systems with deeply subdiffraction limited spatial resolution. Leveraging recent advances in manipulating the spatial phase profile of the transverse electron wavefront, we theoretically describe interactions between the electron probe and optically stimulated nanophotonic targets in which the probe gains energy while simultaneously transitioning between transverse states with distinct phase profiles. Exploiting the selection rules governing such transitions, we propose phase-shaped electron energy gain nanospectroscopy for probing the 3D polarization-resolved response field of an optically excited target with nanoscale spatial resolution. Considering ongoing instrumental developments, polarized generalizations of STEM electron energy loss and gain measurements hold the potential to become powerful tools for fundamental studies of quantum materials and their interaction with nearby nanostructures supporting localized surface plasmon or phonon polaritons as well as for noninvasive imaging and nanoscale 3D field tomography.
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Affiliation(s)
- Marc R Bourgeois
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Austin G Nixon
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Matthieu Chalifour
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Elliot K Beutler
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - David J Masiello
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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4
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Jenkinson K, Liz-Marzán LM, Bals S. Multimode Electron Tomography Sheds Light on Synthesis, Structure, and Properties of Complex Metal-Based Nanoparticles. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2110394. [PMID: 35438805 DOI: 10.1002/adma.202110394] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 03/24/2022] [Indexed: 06/14/2023]
Abstract
Electron tomography has become a cornerstone technique for the visualization of nanoparticle morphology in three dimensions. However, to obtain in-depth information about a nanoparticle beyond surface faceting and morphology, different electron microscopy signals must be combined. The most notable examples of these combined signals include annular dark-field scanning transmission electron microscopy (ADF-STEM) with different collection angles and the combination of ADF-STEM with energy-dispersive X-ray or electron energy loss spectroscopies. Here, the experimental and computational development of various multimode tomography techniques in connection to the fundamental materials science challenges that multimode tomography has been instrumental to overcoming are summarized. Although the techniques can be applied to a wide variety of compositions, the study is restricted to metal and metal oxide nanoparticles for the sake of simplicity. Current challenges and future directions of multimode tomography are additionally discussed.
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Affiliation(s)
- Kellie Jenkinson
- EMAT and NANOlab Center of Excellence, University of Antwerp, Antwerp, 2020, Belgium
| | - Luis M Liz-Marzán
- CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), Donostia-San Sebastián, 20014, Spain
- Centro de Investigación Biomédica en Red de Bioingeniería Biomateriales, y Nanomedicina (CIBER-BBN), Donostia-San Sebastián, 20014, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, 48009, Spain
| | - Sara Bals
- EMAT and NANOlab Center of Excellence, University of Antwerp, Antwerp, 2020, Belgium
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5
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Guan G, Zhang A, Xie X, Meng Y, Zhang W, Zhou J, Liang H. Far-Field and Non-Intrusive Optical Mapping of Nanoscale Structures. NANOMATERIALS 2022; 12:nano12132274. [PMID: 35808109 PMCID: PMC9268055 DOI: 10.3390/nano12132274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 12/04/2022]
Abstract
Far-field high-density optics storage and readout involve the interaction of a sub-100 nm beam profile laser to store and retrieve data with nanostructure media. Hence, understanding the light–matter interaction responding in the far-field in such a small scale is essential for effective optical information processing. We present a theoretical analysis and an experimental study for far-field and non-intrusive optical mapping of nanostructures. By a comprehensive analytical derivation for interaction between the modulated light and the target in a confocal laser scanning microscopy (CLSM) configuration, it is found that the CLSM probes the local density of states (LDOSs) in the far field rather than the sample geometric morphology. With a radially polarized (RP) light for illumination, the far-field mapping of LDOS at the optical resolution down to 74 nm is obtained. In addition, it is experimentally verified that the target morphology is mapped only when the far-field mapping of LDOS coincides with the geometric morphology, while light may be blocked from entering the nanostructures medium with weak or missing LDOS, hence invalidating high-density optical information storage and retrieval. In this scenario, nanosphere gaps as small as 33 nm are clearly observed. We further discuss the characterization for far-field and non-intrusive interaction with nanostructures of different geometric morphology and compare them with those obtainable with the projection of near-field LDOS and scanning electronic microscopic results.
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Affiliation(s)
- Guorong Guan
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China; (G.G.); (A.Z.)
- School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou 510275, China
| | - Aiqin Zhang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China; (G.G.); (A.Z.)
- School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou 510275, China
| | - Xiangsheng Xie
- Department of Physics, College of Science, Shantou University, Shantou 515063, China;
| | - Yan Meng
- State Key Laboratory of Analytical Chemistry for Life Science, MOE Key Laboratory of Intelligent Optical Sensing and Manipulation, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China; (Y.M.); (W.Z.)
| | - Weihua Zhang
- State Key Laboratory of Analytical Chemistry for Life Science, MOE Key Laboratory of Intelligent Optical Sensing and Manipulation, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China; (Y.M.); (W.Z.)
| | - Jianying Zhou
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China; (G.G.); (A.Z.)
- School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou 510275, China
- Correspondence: (J.Z.); (H.L.)
| | - Haowen Liang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China; (G.G.); (A.Z.)
- School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou 510275, China
- Correspondence: (J.Z.); (H.L.)
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6
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Wang YC, Wang ZL. The effect of post-acquisition data misalignments on the performance of STEM tomography. Ultramicroscopy 2022; 235:113498. [DOI: 10.1016/j.ultramic.2022.113498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 01/28/2022] [Accepted: 02/16/2022] [Indexed: 11/27/2022]
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7
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Wohlwend J, Sologubenko AS, Döbeli M, Galinski H, Spolenak R. Chemical Engineering of Cu-Sn Disordered Network Metamaterials. NANO LETTERS 2022; 22:853-859. [PMID: 34738817 DOI: 10.1021/acs.nanolett.1c03545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The design and fabrication of large-area metamaterials is an ongoing challenge. In the present work, we propose a scalable design route and low-footprint strategy for the production of large-area, frequency-selective Cu-Sn disordered network metamaterials with quasi-perfect absorption. The nanoscale networks combine the robustness of disordered systems with the broad-band optical response known from connected wire-mesh metamaterials. Using experiments and simulations, we show how frequency-selective absorption in the networks can be designed and controlled. We observe a linear dependence of the optical response as a function of Sn content ranging from the near-infrared to the visible region. The absorbing state exhibits strong sensitivity to both changes in the global network topology and the chemistry of the network. We probe the plasmonic response of these nanometric networks by electron energy loss spectroscopy (EELS), where we resolve extremely confined gap surface-plasmon (GSP) modes.
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Affiliation(s)
- Jelena Wohlwend
- Laboratory for Nanometallurgy, Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
| | - Alla S Sologubenko
- Scientific Center for Light and Electron Microscopy, ScopeM, ETH Zürich, 8093 Zürich, Switzerland
| | - Max Döbeli
- Laboratory of Ion Beam Physics, Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Henning Galinski
- Laboratory for Nanometallurgy, Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
| | - Ralph Spolenak
- Laboratory for Nanometallurgy, Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
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8
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OUP accepted manuscript. Microscopy (Oxf) 2022; 71:i174-i199. [DOI: 10.1093/jmicro/dfab050] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/20/2021] [Accepted: 01/28/2022] [Indexed: 11/14/2022] Open
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9
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Alexander DTL, Flauraud V, Demming-Janssen F. Near-Field Mapping of Photonic Eigenmodes in Patterned Silicon Nanocavities by Electron Energy-Loss Spectroscopy. ACS NANO 2021; 15:16501-16514. [PMID: 34585583 DOI: 10.1021/acsnano.1c06065] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Recently, there has been significant interest in using dielectric nanocavities for the controlled scattering of light, owing to the diverse electromagnetic modes that they support. For plasmonic systems, electron energy-loss spectroscopy (EELS) is now an established method enabling structure-optical property analysis at the scale of the nanostructure. Here, we instead test its potential for the near-field mapping of photonic eigenmodes supported in planar dielectric nanocavities, which are lithographically patterned from amorphous silicon according to standard photonic principles. By correlating results with finite element simulations, we demonstrate how many of the EELS excitations can be directly corresponded to various optical eigenmodes of interest for photonic engineering. The EELS maps present a high spatial definition, displaying intensity features that correlate precisely to the impact parameters giving the highest probability of modal excitation. Further, eigenmode characteristics translate into their EELS signatures, such as the spatially and energetically extended signal of the low Q-factor electric dipole and nodal intensity patterns emerging from excitation of toroidal and second-order magnetic modes within the nanocavity volumes. Overall, the spatial-spectral nature of the data, combined with our experimental-simulation toolbox, enables interpretation of subtle changes in the EELS response across a range of nanocavity dimensions and forms, with certain simulated resonances matching the excitation energies within ±0.01 eV. By connecting results to far-field simulations, perspectives are offered for tailoring the nanophotonic resonances via manipulating nanocavity size and shape.
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Affiliation(s)
- Duncan T L Alexander
- Electron Spectrometry and Microscopy Laboratory (LSME), Institute of Physics (IPHYS), École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Valentin Flauraud
- Microsystems Laboratory (LMIS1), Microengineering Institute (IMT), École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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10
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Li X, Haberfehlner G, Hohenester U, Stéphan O, Kothleitner G, Kociak M. Three-dimensional vectorial imaging of surface phonon polaritons. Science 2021; 371:1364-1367. [PMID: 33766884 DOI: 10.1126/science.abg0330] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 02/12/2021] [Indexed: 12/18/2022]
Abstract
Surface phonon polaritons (SPhPs) are coupled photon-phonon excitations that emerge at the surfaces of nanostructured materials. Although they strongly influence the optical and thermal behavior of nanomaterials, no technique has been able to reveal the complete three-dimensional (3D) vectorial picture of their electromagnetic density of states. Using a highly monochromated electron beam in a scanning transmission electron microscope, we could visualize varying SPhP signatures from nanoscale MgO cubes as a function of the beam position, energy loss, and tilt angle. The SPhPs' response was described in terms of eigenmodes and used to tomographically reconstruct the phononic surface electromagnetic fields of the object. Such 3D information promises insights in nanoscale physical phenomena and is invaluable to the design and optimization of nanostructures for fascinating new uses.
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Affiliation(s)
- Xiaoyan Li
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405 Orsay. France
| | - Georg Haberfehlner
- Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria
| | - Ulrich Hohenester
- Institute of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Odile Stéphan
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405 Orsay. France
| | - Gerald Kothleitner
- Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria. .,Graz Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
| | - Mathieu Kociak
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405 Orsay. France.
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11
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Kuhness D, Gruber A, Winkler R, Sattelkow J, Fitzek H, Letofsky-Papst I, Kothleitner G, Plank H. High-Fidelity 3D Nanoprinting of Plasmonic Gold Nanoantennas. ACS APPLIED MATERIALS & INTERFACES 2021; 13:1178-1191. [PMID: 33372522 DOI: 10.1021/acsami.0c17030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The direct-write fabrication of freestanding nanoantennas for plasmonic applications is a challenging task, as demands for overall morphologies, nanoscale features, and material qualities are very high. Within the small pool of capable technologies, three-dimensional (3D) nanoprinting via focused electron beam-induced deposition (FEBID) is a promising candidate due to its design flexibility. As FEBID materials notoriously suffer from high carbon contents, the chemical postgrowth transfer into pure metals is indispensably needed, which can severely harm or even destroy FEBID-based 3D nanoarchitectures. Following this challenge, we first dissect FEBID growth characteristics and then combine individual advantages by an advanced patterning approach. This allows the direct-write fabrication of high-fidelity shapes with nanoscale features in the sub-10 nm range, which allow a shape-stable chemical transfer into plasmonically active Au nanoantennas. The here-introduced strategy is a generic approach toward more complex 3D architectures for future applications in the field of 3D plasmonics.
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Affiliation(s)
- David Kuhness
- Christian Doppler Laboratory for Direct-Write Fabrication of 3D Nano-Probes, Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, 8010 Graz, Austria
| | | | - Robert Winkler
- Christian Doppler Laboratory for Direct-Write Fabrication of 3D Nano-Probes, Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, 8010 Graz, Austria
| | - Jürgen Sattelkow
- Christian Doppler Laboratory for Direct-Write Fabrication of 3D Nano-Probes, Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, 8010 Graz, Austria
| | - Harald Fitzek
- Graz Centre for Electron Microscopy, 8010 Graz, Austria
| | - Ilse Letofsky-Papst
- Graz Centre for Electron Microscopy, 8010 Graz, Austria
- Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, 8010 Graz, Austria
| | - Gerald Kothleitner
- Graz Centre for Electron Microscopy, 8010 Graz, Austria
- Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, 8010 Graz, Austria
| | - Harald Plank
- Christian Doppler Laboratory for Direct-Write Fabrication of 3D Nano-Probes, Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, 8010 Graz, Austria
- Graz Centre for Electron Microscopy, 8010 Graz, Austria
- Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, 8010 Graz, Austria
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12
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Schmidt FP, Losquin A, Horák M, Hohenester U, Stöger-Pollach M, Krenn JR. Fundamental Limit of Plasmonic Cathodoluminescence. NANO LETTERS 2021; 21:590-596. [PMID: 33336569 PMCID: PMC7809694 DOI: 10.1021/acs.nanolett.0c04084] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/27/2020] [Indexed: 06/12/2023]
Abstract
We use cathodoluminescence (CL) spectroscopy in a transmission electron microscope to probe the radial breathing mode of plasmonic silver nanodisks. A two-mirror detection system sandwiching the sample collects the CL emission in both directions, that is, backward and forward with respect to the electron beam trajectory. We unambiguously identify a spectral shift of about 8 nm in the CL spectra acquired from both sides and show that this asymmetry is induced by the electron beam itself. By numerical simulations, we confirm the observations and identify the underlying physical effect due to the interference of the CL emission patterns of an electron-beam-induced dipole and the breathing mode. This effect can ultimately limit the achievable fidelity in CL measurements on any system involving multiple excitations and should therefore be considered with care in high-precision experiments.
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Affiliation(s)
| | - Arthur Losquin
- Thales
Research and Technology, 1 avenue Augustin Fresnel, Palaiseau 91767, France
| | - Michal Horák
- Central
European Institute of Technology, Brno University
of Technology, Brno Purkynǒva 123, 612 00, Czech Republic
| | - Ulrich Hohenester
- Institute
of Physics, University of Graz, Universitätsplatz 5, Graz 8010, Austria
| | - Michael Stöger-Pollach
- University
Service Centre for Transmission Electron Microscopy, TU Wien, Wiedner Hauptstraße 8-10, Wien 1040, Austria
| | - Joachim R. Krenn
- Institute
of Physics, University of Graz, Universitätsplatz 5, Graz 8010, Austria
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13
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Affiliation(s)
- Dongdong Xiao
- Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Beijing 100190 China
- School of physical sciencesUniversity of Chinese Academy of Sciences Beijing 100049 China
- Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China
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14
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Controlling free electrons with optical whispering-gallery modes. Nature 2020; 582:46-49. [PMID: 32494079 DOI: 10.1038/s41586-020-2320-y] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 03/06/2020] [Indexed: 11/08/2022]
Abstract
Free-electron beams are versatile probes of microscopic structure and composition1,2, and have revolutionized atomic-scale imaging in several fields, from solid-state physics to structural biology3. Over the past decade, the manipulation and interaction of electrons with optical fields have enabled considerable progress in imaging methods4, near-field electron acceleration5,6, and four-dimensional microscopy techniques with high temporal and spatial resolution7. However, electron beams typically couple only weakly to optical excitations, and emerging applications in electron control and sensing8-11 require large enhancements using tailored fields and interactions. Here we couple a free-electron beam to a travelling-wave resonant cavity mode. The enhanced interaction with the optical whispering-gallery modes of dielectric microresonators induces a strong phase modulation on co-propagating electrons, which leads to a spectral broadening of 700 electronvolts, corresponding to the absorption and emission of hundreds of photons. By mapping the near-field interaction with ultrashort electron pulses in space and time, we trace the lifetime of the the microresonator following a femtosecond excitation and observe the spectral response of the cavity. The natural matching of free electrons to these quintessential optical modes could enable the application of integrated photonics technology in electron microscopy, with broad implications for attosecond structuring, probing quantum emitters and possible electron-light entanglement.
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15
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Suzuki H, Imaeda K, Mizobata H, Imura K. Spatial characteristics of optical fields near a gold nanorod revealed by three-dimensional scanning near-field optical microscopy. J Chem Phys 2020; 152:014708. [PMID: 31914735 DOI: 10.1063/1.5131709] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We visualize plasmon mode patterns induced in a single gold nanorod by three-dimensional scanning near-field optical microscopy. From the near-field transmission imaging, we find that 3rd and 4th order plasmon modes are resonantly excited in the nanorod. We perform electromagnetic simulations based on the discrete dipole approximation method under focused Gaussian beam illumination and demonstrate that the observed near-field spectral and spatial features are well reproduced by the simulation. We also reveal from the three-dimensional near-field microscopy that the 4th order plasmon mode confines optical fields more tightly compared with the 3rd order mode. This result indicates that the even-order plasmon modes are promising for enhancing the light-matter interactions.
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Affiliation(s)
- Hiromasa Suzuki
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo 169-8555, Japan
| | - Keisuke Imaeda
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo 169-8555, Japan
| | - Hidetoshi Mizobata
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo 169-8555, Japan
| | - Kohei Imura
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo 169-8555, Japan
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16
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Kiselev A, Bernasconi GD, Martin OJF. Modes interplay and dynamics in the second harmonic generation of plasmonic nanostructures. OPTICS EXPRESS 2019; 27:38708-38720. [PMID: 31878633 DOI: 10.1364/oe.382041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 12/10/2019] [Indexed: 06/10/2023]
Abstract
The full wave surface integral equation computation of the second harmonic generation (SHG) dynamics for metal spheres and nanorods - presented as multimedia files - is performed to reveal the dynamics of the modes supported by the nanostructure. We demonstrate that the interplay between different modes controls the nonlinear response and that the size-induced redshift of the eigenmodes can be manipulated by adjusting the nanostructure geometry, so that the SHG signal can be boosted at specified frequencies. We show that the SHG radiation is not necessarily quadrupolar in spherical nanoparticles, as it is often assumed. Finally, we introduce an efficient way to reduce the SHG calculation time.
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17
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Polman A, Kociak M, García de Abajo FJ. Electron-beam spectroscopy for nanophotonics. NATURE MATERIALS 2019; 18:1158-1171. [PMID: 31308514 DOI: 10.1038/s41563-019-0409-1] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 05/04/2019] [Accepted: 05/14/2019] [Indexed: 05/22/2023]
Abstract
Progress in electron-beam spectroscopies has recently enabled the study of optical excitations with combined space, energy and time resolution in the nanometre, millielectronvolt and femtosecond domain, thus providing unique access into nanophotonic structures and their detailed optical responses. These techniques rely on ~1-300 keV electron beams focused at the sample down to sub-nanometre spots, temporally compressed in wavepackets a few femtoseconds long, and in some cases controlled by ultrafast light pulses. The electrons undergo energy losses and gains (also giving rise to cathodoluminescence light emission), which are recorded to reveal the optical landscape along the beam path. This Review portraits these advances, with a focus on coherent excitations, emphasizing the increasing level of control over the electron wavefunctions and ensuing applications in the study and technological use of optically resonant modes and polaritons in nanoparticles, 2D materials and engineered nanostructures.
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Affiliation(s)
- Albert Polman
- Center for Nanophotonics, AMOLF, Amsterdam, the Netherlands.
| | - Mathieu Kociak
- Laboratoire de Physique des Solides, Université de Paris-Sud, Orsay, France
| | - F Javier García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
- ICREA-Institució Catalana de Reserca I Estudis Avançats, Barcelona, Spain
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18
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Schefold J, Meuret S, Schilder N, Coenen T, Agrawal H, Garnett EC, Polman A. Spatial Resolution of Coherent Cathodoluminescence Super-Resolution Microscopy. ACS PHOTONICS 2019; 6:1067-1072. [PMID: 31024982 PMCID: PMC6473507 DOI: 10.1021/acsphotonics.9b00164] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Indexed: 05/29/2023]
Abstract
We investigate the nanoscale excitation of Ag nanocubes with coherent cathodoluminescence imaging spectroscopy (CL) to resolve the factors that determine the spatial resolution of CL as a deep-subwavelength imaging technique. The 10-30 keV electron beam coherently excites localized plasmons in 70 nm Ag cubes at 2.4 and 3.1 eV. The radiation from these plasmon modes is collected in the far-field together with the secondary electron intensity. CL line scans across the nanocubes show exponentially decaying tails away from the cube that reveal the evanescent coupling of the electron field to the resonant plasmon modes. The measured CL decay lengths range from 8 nm (10 keV) to 12 nm (30 keV) and differ from the calculated ones by only 1-3 nm. A statistical model of electron scattering inside the Ag nanocubes is developed to analyze the secondary electron images and compare them with the CL data. The Ag nanocube edges are derived from the CL line scans with a systematic error less than 3 nm. The data demonstrate that CL probes the electron-induced plasmon fields with nanometer accuracy.
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Affiliation(s)
- Joris Schefold
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Sophie Meuret
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Nick Schilder
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Toon Coenen
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
- Delmic B.V., Kanaalweg
4, 2628
EB Delft, The Netherlands
| | - Harshal Agrawal
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Erik C. Garnett
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Albert Polman
- Center
for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
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19
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Huber R, Haberfehlner G, Holler M, Kothleitner G, Bredies K. Total generalized variation regularization for multi-modal electron tomography. NANOSCALE 2019; 11:5617-5632. [PMID: 30864603 DOI: 10.1039/c8nr09058k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In multi-modal electron tomography, tilt series of several signals such as X-ray spectra, electron energy-loss spectra, annular dark-field, or bright-field data are acquired at the same time in a transmission electron microscope and subsequently reconstructed in three dimensions. However, the acquired data are often incomplete and suffer from noise, and generally each signal is reconstructed independently of all other signals, not taking advantage of correlation between different datasets. This severely limits both the resolution and validity of the reconstructed images. In this paper, we show how image quality in multi-modal electron tomography can be greatly improved by employing variational modeling and multi-channel regularization techniques. To achieve this aim, we employ a coupled Total Generalized Variation (TGV) regularization that exploits correlation between different channels. In contrast to other regularization methods, coupled TGV regularization allows to reconstruct both hard transitions and gradual changes inside each sample, and links different channels at the level of first and higher order derivatives. This favors similar interface positions for all reconstructions, thereby improving the image quality for all data, in particular, for 3D elemental maps. We demonstrate the joint multi-channel TGV reconstruction on tomographic energy-dispersive X-ray spectroscopy (EDXS) and high-angle annular dark field (HAADF) data, but the reconstruction method is generally applicable to all types of signals used in electron tomography, as well as all other types of projection-based tomographies.
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Affiliation(s)
- Richard Huber
- Institute for Mathematics and Scientific Computing, University of Graz, Heinrichstraße 36, A-8010 Graz, Austria.
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20
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Matsuura T, Imaeda K, Hasegawa S, Suzuki H, Imura K. Characterization of Overlapped Plasmon Modes in a Gold Hexagonal Plate Revealed by Three-Dimensional Near-Field Optical Microscopy. J Phys Chem Lett 2019; 10:819-824. [PMID: 30735394 DOI: 10.1021/acs.jpclett.8b03578] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
A detailed characterization of plasmon modes is important not only for a deeper understanding of plasmons but also for their practical applications. In this study, we investigated the three-dimensional near-field characteristics of high-order plasmon modes excited in a gold hexagonal nanoplate. From the near-field spectroscopic images, we found that both in-plane and out-of-plane plasmon modes observed near 900 nm were spectrally and spatially overlapped. We performed three-dimensional near-field measurement to reveal the optical characteristics of the overlapped modes in detail. We found that the steric near-field distribution near the nanoplate strongly depended on the plasmon mode, and the out-of-plane mode confines electromagnetic fields more tightly than the in-plane mode. We also found that the in-plane mode was dominantly visualized as the probe tip-sample distance increased. These findings demonstrate that the three-dimensional near-field technique enables selective visualization of a single plasmon mode even if multiple modes are spatially and spectrally overlapped.
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Affiliation(s)
- Takuya Matsuura
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering , Waseda University , Shinjuku , Tokyo 169-8555 , Japan
| | - Keisuke Imaeda
- Research Institute for Science and Engineering , Waseda University , Shinjuku , Tokyo 169-8555 , Japan
| | - Seiju Hasegawa
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering , Waseda University , Shinjuku , Tokyo 169-8555 , Japan
| | - Hiromasa Suzuki
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering , Waseda University , Shinjuku , Tokyo 169-8555 , Japan
| | - Kohei Imura
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering , Waseda University , Shinjuku , Tokyo 169-8555 , Japan
- Research Institute for Science and Engineering , Waseda University , Shinjuku , Tokyo 169-8555 , Japan
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21
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Zhang KJ, Lu DB, Da B, Ding ZJ. Coupling of Surface Plasmon Modes and Refractive Index Sensitivity of Hollow Silver Nanoprism. Sci Rep 2018; 8:15993. [PMID: 30375478 PMCID: PMC6207745 DOI: 10.1038/s41598-018-34477-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 10/16/2018] [Indexed: 11/28/2022] Open
Abstract
Localized surface plasmon (LSP) modes depend strongly on the morphology of nanoparticle and the surrounding dielectric medium. The hollow nanostructure provides a new way to modulate the surface plasmon modes due to the additional cavity surface. In this work, we study systematically the multipolar surface plasmon modes of hollow silver nanoprism (HSN) by simulation of electron energy loss spectroscopy (EELS) spectra based on the boundary element method (BEM). Herein the effects of the cavity size and position are taken into account. The LSP modes of HSNs are compared with those of perfect silver nanoprism (SN). The red-shift behaviors of multipolar modes can be found as increasing the cavity size. Modes A and C have similar red-shift tendency and obey the plasmon ruler equation, which can be explained by dipole-dipole coupling mode. Meanwhile, the degenerate modes will be split by changing the cavity position, and opposite shift tendencies of split degenerate states are observed. These are caused by different coupling nature of degenerate modes. Moreover, high refractive index sensitivity (RIS) can be obtained for HSN by changing the cavity size and position.
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Affiliation(s)
- K J Zhang
- Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences; Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - D B Lu
- Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences; Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - B Da
- Center for Materials Research by Information Integration, Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan.
| | - Z J Ding
- Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences; Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China.
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22
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Krehl J, Guzzinati G, Schultz J, Potapov P, Pohl D, Martin J, Verbeeck J, Fery A, Büchner B, Lubk A. Spectral field mapping in plasmonic nanostructures with nanometer resolution. Nat Commun 2018; 9:4207. [PMID: 30310063 PMCID: PMC6181996 DOI: 10.1038/s41467-018-06572-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 08/29/2018] [Indexed: 11/10/2022] Open
Abstract
Plasmonic nanostructures and -devices are rapidly transforming light manipulation technology by allowing to modify and enhance optical fields on sub-wavelength scales. Advances in this field rely heavily on the development of new characterization methods for the fundamental nanoscale interactions. However, the direct and quantitative mapping of transient electric and magnetic fields characterizing the plasmonic coupling has been proven elusive to date. Here we demonstrate how to directly measure the inelastic momentum transfer of surface plasmon modes via the energy-loss filtered deflection of a focused electron beam in a transmission electron microscope. By scanning the beam over the sample we obtain a spatially and spectrally resolved deflection map and we further show how this deflection is related quantitatively to the spectral component of the induced electric and magnetic fields pertaining to the mode. In some regards this technique is an extension to the established differential phase contrast into the dynamic regime.
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Affiliation(s)
- J Krehl
- IFW Dresden, Helmholtzstr. 20, 01069, Dresden, Germany.
| | - G Guzzinati
- EMAT, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium
| | - J Schultz
- IFW Dresden, Helmholtzstr. 20, 01069, Dresden, Germany
| | - P Potapov
- IFW Dresden, Helmholtzstr. 20, 01069, Dresden, Germany
| | - D Pohl
- IFW Dresden, Helmholtzstr. 20, 01069, Dresden, Germany.,Dresden Center for Nanoanalysis, TU Dresden, 01062, Dresden, Germany
| | - Jérôme Martin
- Institut Charles Delaunay - Laboratoire de nanotechnologies et d'instrumentation optique, UMR CNRS 6281, Université de Technologie de Troyes, 10010, Troyes, France
| | - J Verbeeck
- EMAT, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium
| | - A Fery
- IPF Dresden, Hohe Str. 3, 01069, Dresden, Germany
| | - B Büchner
- IFW Dresden, Helmholtzstr. 20, 01069, Dresden, Germany
| | - A Lubk
- IFW Dresden, Helmholtzstr. 20, 01069, Dresden, Germany.
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23
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Horák M, Bukvišová K, Švarc V, Jaskowiec J, Křápek V, Šikola T. Comparative study of plasmonic antennas fabricated by electron beam and focused ion beam lithography. Sci Rep 2018; 8:9640. [PMID: 29941880 PMCID: PMC6018609 DOI: 10.1038/s41598-018-28037-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/14/2018] [Indexed: 11/09/2022] Open
Abstract
We present a comparative study of plasmonic antennas fabricated by electron beam lithography and direct focused ion beam milling. We have investigated optical and structural properties and chemical composition of gold disc-shaped plasmonic antennas on a silicon nitride membrane fabricated by both methods to identify their advantages and disadvantages. Plasmonic antennas were characterized using transmission electron microscopy including electron energy loss spectroscopy and energy dispersive X-ray spectroscopy, and atomic force microscopy. We have found stronger plasmonic response with better field confinement in the antennas fabricated by electron beam lithography, which is attributed to their better structural quality, homogeneous thickness, and only moderate contamination mostly of organic nature. Plasmonic antennas fabricated by focused ion beam lithography feature weaker plasmonic response, lower structural quality with pronounced thickness fluctuations, and strong contamination, both organic and inorganic, including implanted ions from the focused beam. While both techniques are suitable for the fabrication of plasmonic antennas, electron beam lithography shall be prioritized over focused ion beam lithography due to better quality and performance of its products.
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Affiliation(s)
- Michal Horák
- Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic.
| | - Kristýna Bukvišová
- Institute of Physical Engineering, Brno University of Technology, Technická 2, 616 69, Brno, Czech Republic
| | - Vojtěch Švarc
- Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic.,Institute of Physical Engineering, Brno University of Technology, Technická 2, 616 69, Brno, Czech Republic
| | - Jiří Jaskowiec
- Institute of Physical Engineering, Brno University of Technology, Technická 2, 616 69, Brno, Czech Republic
| | - Vlastimil Křápek
- Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic.,Institute of Physical Engineering, Brno University of Technology, Technická 2, 616 69, Brno, Czech Republic
| | - Tomáš Šikola
- Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic.,Institute of Physical Engineering, Brno University of Technology, Technická 2, 616 69, Brno, Czech Republic
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24
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Schmidt FP, Losquin A, Hofer F, Hohenau A, Krenn JR, Kociak M. How Dark Are Radial Breathing Modes in Plasmonic Nanodisks? ACS PHOTONICS 2018; 5:861-866. [PMID: 29607350 PMCID: PMC5871341 DOI: 10.1021/acsphotonics.7b01060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Indexed: 05/06/2023]
Abstract
Due to a vanishing dipole moment, radial breathing modes in small flat plasmonic nanoparticles do not couple to light and have to be probed with a near-field source, as in electron energy loss spectroscopy (EELS). With increasing particle size, retardation gives rise to light coupling, enabling probing breathing modes optically or by cathodoluminescence (CL). Here, we investigate single silver nanodisks with diameters of 150-500 nm by EELS and CL in an electron microscope and quantify the EELS/CL ratio, which corresponds to the ratio of full to radiative damping of the breathing mode. For the investigated diameter range, we find the CL signal to increase by about 1 order of magnitude, in agreement with numerical simulations. Due to reciprocity, our findings corroborate former optical experiments and enable a quantitative understanding of the light coupling of dark plasmonic modes.
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Affiliation(s)
- Franz-Philipp Schmidt
- Institute
of Physics, University of Graz, Graz 8010, Austria
- Institute
for Electron Microscopy and Nanoanalysis, Graz University of Technology, Graz 8010, Austria
- E-mail:
| | - Arthur Losquin
- Department
of Physics, Lund University, Lund 221 00, Sweden
- Laboratoire
Ondes et Matière d’Aquitaine, UMR 5798, CNRS-University of Bordeaux, F-33405 Talence Cedex, France
| | - Ferdinand Hofer
- Institute
for Electron Microscopy and Nanoanalysis, Graz University of Technology, Graz 8010, Austria
| | - Andreas Hohenau
- Institute
of Physics, University of Graz, Graz 8010, Austria
| | | | - Mathieu Kociak
- Laboratoire
de Physique des Solides, CNRS UMR 8502,
Université Paris-Sud, 91405 Orsay, France
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25
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Haberfehlner G, Schmidt FP, Schaffernak G, Hörl A, Trügler A, Hohenau A, Hofer F, Krenn JR, Hohenester U, Kothleitner G. 3D Imaging of Gap Plasmons in Vertically Coupled Nanoparticles by EELS Tomography. NANO LETTERS 2017; 17:6773-6777. [PMID: 28981295 PMCID: PMC5683695 DOI: 10.1021/acs.nanolett.7b02979] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Plasmonic gap modes provide the ultimate confinement of optical fields. Demanding high spatial resolution, the direct imaging of these modes was only recently achieved by electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM). However, conventional 2D STEM-EELS is only sensitive to components of the photonic local density of states (LDOS) parallel to the electron trajectory. It is thus insensitive to specific gap modes, a restriction that was lifted with the introduction of tomographic 3D EELS imaging. Here, we show that by 3D EELS tomography the gap mode LDOS of a vertically stacked nanotriangle dimer can be fully imaged. Besides probing the complete mode spectrum, we demonstrate that the tomographic approach allows disentangling the signal contributions from the two nanotriangles that superimpose in a single measurement with a fixed electron trajectory. Generally, vertically coupled nanoparticles enable the tailoring of 3D plasmonic fields, and their full characterization will thus aid the development of complex nanophotonic devices.
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Affiliation(s)
- Georg Haberfehlner
- Graz
Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
- Institute
of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria
- E-mail:
| | - Franz-Philipp Schmidt
- Institute
of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria
- Institute
of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Gernot Schaffernak
- Institute
of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Anton Hörl
- Institute
of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Andreas Trügler
- Institute
of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Andreas Hohenau
- Institute
of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Ferdinand Hofer
- Graz
Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
- Institute
of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria
| | - Joachim R. Krenn
- Institute
of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Ulrich Hohenester
- Institute
of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Gerald Kothleitner
- Graz
Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
- Institute
of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria
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