Abstract
Ultrathin dielectric gaps between metals can trap plasmonic optical modes with surprisingly low loss and with volumes below 1 nm3. We review the origin and subtle properties of these modes, and show how they can be well accounted for by simple models. Particularly important is the mixing between radiating antennas and confined nanogap modes, which is extremely sensitive to precise nanogeometry, right down to the single-atom level. Coupling nanogap plasmons to electronic and vibronic transitions yields a host of phenomena including single-molecule strong coupling and molecular optomechanics, opening access to atomic-scale chemistry and materials science, as well as quantum metamaterials. Ultimate low-energy devices such as robust bottom-up assembled single-atom switches are thus in prospect.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Ritchie, R. H. Plasma losses by fast electrons in thin films. Phys. Rev. 106, 874–881 (1957).
Krenn, J. R. et al. Squeezing the optical near-field zone by plasmon coupling of metallic nanoparticles. Phys. Rev. Lett. 82, 2590–2593 (1999).
Krenn, J. R. et al. Direct observation of localized surface plasmon coupling. Phys. Rev. B 60, 5029–5033 (1999).
Ditlbacher, H., Krenn, J. R., Schider, G., Leitner, A. & Aussenegg, F. R. Two-dimensional optics with surface plasmon polaritons. Appl. Phys. Lett. 81, 1762–1764 (2002).
Maier, S. A. et al. Local detection of electromagnetic energy transport below the diffraction limit in metal nanoparticle plasmon waveguides. Nat. Mater. 2, 229–232 (2003).
Gramotnev, D. K. & Bozhevolnyi, S. I. Plasmonics beyond the diffraction limit. Nat. Photon. 4, 83–91 (2010).
Yang, W., Schatz, G. C. & Van Duyne, R. P. Discrete dipole approximation for calculating extinction and Raman intensities for small particles with arbitrary shapes. J. Chem. Phys. 103, 869–875 (1995).
Kottmann, J. P., Martin, O. J. F., Smith, D. R. & Schultz, S. Spectral response of plasmon resonant nanoparticles with a non-regular shape. Opt. Express 6, 213–219 (2000).
Mock, J. J., Barbic, M., Smith, D. R., Schultz, D. A. & Schultz, S. Shape effects in plasmon resonance of individual colloidal silver nanoparticles. J. Chem. Phys. 116, 6755–6759 (2002).
Kelly, K. L., Coronado, E., Zhao, L. L. & Schatz, G. C. The optical properties of metal nanoparticles: the influence of size, shape, and dielectric environment. J. Phys. Chem. B 107, 668–677 (2003).
Xu, H., Bjerneld, E. J., Käll, M. & Börjesson, L. Spectroscopy of single hemoglobin molecules by surface enhanced Raman scattering. Phys. Rev. Lett. 83, 4357–4360 (1999).
Kottmann, J. P. & Martin, O. J. F. Plasmon resonant coupling in metallic nanowires. Opt. Express 8, 655–663 (2001).
Hao, E. & Schatz, G. C. Electromagnetic fields around silver nanoparticles and dimers. J. Chem. Phys. 120, 357–366 (2004).
Ghosh, S. K. & Pal, T. Interparticle coupling effect on the surface plasmon resonance of gold nanoparticles: from theory to applications. Chem. Rev. 107, 4797–4862 (2007).
Romero, I., Aizpurua, J., Bryant, G. W. & García De Abajo, F. J. Plasmons in nearly touching metallic nanoparticles: singular response in the limit of touching dimers. Opt. Express 14, 9988 (2006).
Koh, A. L., Fernández-Domínguez, A. I., McComb, D. W., Maier, S. A. & Yang, J. K. W. High-resolution mapping of electron-beam-excited plasmon modes in lithographically defined gold nanostructures. Nano Lett. 11, 1323–1330 (2011).
Lévêque, G. & Martin, O. J. F. Optical interactions in a plasmonic particle coupled to a metallic film. Opt. Express 14, 9971–9981 (2006).
Nordlander, P. & Le, F. Plasmonic structure and electromagnetic field enhancements in the metallic nanoparticle-film system. Appl. Phys. B 84, 35–41 (2006).
Kern, J. et al. Atomic-scale confinement of resonant optical fields. Nano Lett. 12, 5504–5509 (2012).
Zhang, R. et al. Chemical mapping of a single molecule by plasmon-enhanced Raman scattering. Nature 498, 82–86 (2013).
Zhang, Y. et al. Sub-nanometre control of the coherent interaction between a single molecule and a plasmonic nanocavity. Nat. Commun. 8, 15225 (2017).
Dathe, A., Ziegler, M., Hübner, U., Fritzsche, W. & Stranik, O. Electrically excited plasmonic nanoruler for biomolecule detection. Nano Lett. 16, 5728–5736 (2016).
Tuniz, A. & Schmidt, M. A. Interfacing optical fibers with plasmonic nanoconcentrators. Nanophotonics 7, 1279–1298 (2018).
Kuttge, M., García de Abajo, F. J. & Polman, A. Ultrasmall mode volume plasmonic nanodisk resonators. Nano Lett. 10, 1537–1541 (2010).
Hu, M., Ghoshal, A., Marquez, M. & Kik, P. G. Single particle spectroscopy study of metal-film-induced tuning of silver nanoparticle plasmon resonances. J. Phys. Chem. C 114, 7509–7514 (2010).
Mock, J. J. et al. Distance-dependent plasmon resonant coupling between a gold nanoparticle and gold film. Nano Lett. 8, 2245–2252 (2008).
Ciraci, C. et al. Probing the ultimate limits of plasmonic enhancement. Science 337, 1072–1074 (2012).
Mertens, J. et al. Controlling subnanometer gaps in plasmonic dimers using graphene. Nano Lett. 13, 5033–5038 (2013).
Shvets, G. Photonic approach to making a material with a negative index of refraction. Phys. Rev. B 67, 035109 (2003).
Dionne, J. A., Sweatlock, L. A., Atwater, H. A. & Polman, A. Plasmon slot waveguides: towards chip-scale propagation with subwavelength-scale localization. Phys. Rev. B 73, 035407 (2006).
Benz, F. et al. Single-molecule optomechanics in “picocavities”. Science 354, 726–729 (2016).
Lee, K. F. Principles of Antenna Theory. (Wiley, Hoboken, 1984).
Parzefall, M. et al. Antenna-coupled photon emission from hexagonal boron nitride tunnel junctions. Nat. Nanotechnol. 10, 1058–1063 (2015).
Du, W., Wang, T., Chu, H.-S. & Nijhuis, C. A. Highly efficient on-chip direct electronic–plasmonic transducers. Nat. Photon. 11, 623–627 (2017).
Bozhevolnyi, S. I. & Søndergaard, T. General properties of slow-plasmon resonant nanostructures: nano-antennas and resonators. Opt. Express 15, 10869 (2007).
Zayats, A. V., Smolyaninov, I. I. & Maradudin, A. A. Nano-optics of surface plasmon polaritons. Phys. Rep. 408, 131–314 (2005).
Kuttge, M., Cai, W., García de Abajo, F. J. & Polman, A. Dispersion of metal-insulator-metal plasmon polaritons probed by cathodoluminescence imaging spectroscopy. Phys. Rev. B 80, 033409 (2009).
Sigle, D. O. et al. Monitoring morphological changes in 2D monolayer semiconductors using atom-thick plasmonic nanocavities. ACS Nano 9, 825–830 (2015).
Alcaraz Iranzo, D. et al. Probing the ultimate plasmon confinement limits with a van der Waals heterostructure. Science 360, 291–295 (2018).
Tserkezis, C. et al. Hybridization of plasmonic antenna and cavity modes: extreme optics of nanoparticle-on-mirror nanogaps. Phys. Rev. A 92, 053811 (2015).
Kleemann, M.-E. et al. Revealing nanostructures through plasmon polarimetry. ACS Nano 11, 850–855 (2017).
Engheta, N., Salandrino, A. & Alù, A. Circuit elements at optical frequencies: nanoinductors, nanocapacitors, and nanoresistors. Phys. Rev. Lett. 95, 095504 (2005).
Liu, N. et al. Individual nanoantennas loaded with three-dimensional optical nanocircuits. Nano Lett. 13, 142–147 (2013).
Greffet, J.-J., Laroche, M. & Marquier, F. Impedance of a nanoantenna and a single quantum emitter. Phys. Rev. Lett. 105, 117701 (2010).
Benz, F. et al. Generalized circuit model for coupled plasmonic systems. Opt. Express 23, 33255 (2015).
Benz, F. et al. SERS of individual nanoparticles on a mirror: size does matter, but so does shape. J. Phys. Chem. Lett. 7, 2264–2269 (2016).
Bowen, P. T. & Smith, D. R. Coupled-mode theory for film-coupled plasmonic nanocubes. Phys. Rev. B 90, 195402 (2014).
Esteban, R. et al. The morphology of narrow gaps modifies the plasmonic response. ACS Photon. 2, 295–305 (2015).
Li, R.-Q., Hernángomez-Pérez, D., García-Vidal, F. J. & Fernández-Domínguez, A. I. Transformation optics approach to plasmon-exciton strong coupling in nanocavities. Phys. Rev. Lett. 117, 107401 (2016).
Chikkaraddy, R. et al. How ultranarrow gap symmetries control plasmonic nanocavity modes: from cubes to spheres in the nanoparticle-on-mirror. ACS Photon. 4, 469–475 (2017).
Savage, K. J. et al. Revealing the quantum regime in tunnelling plasmonics. Nature 491, 574–577 (2012).
Sauvan, C., Hugonin, J. P., Maksymov, I. S. & Lalanne, P. Theory of the spontaneous optical emission of nanosize photonic and plasmon resonators. Phys. Rev. Lett. 110, 237401 (2013).
Sanders, A. et al. Understanding the plasmonics of nanostructured atomic force microscopy tips. Appl. Phys. Lett. 109, 109–112 (2016).
Ropers, C. et al. Grating-coupling of surface plasmons onto metallic tips: a nanoconfined light source. Nano Lett. 7, 2784–2788 (2007).
Marchesin, F., Koval, P., Barbry, M., Aizpurua, J. & Sánchez-Portal, D. Plasmonic response of metallic nanojunctions driven by single atom motion: quantum transport revealed in optics. ACS Photon. 3, 269–277 (2016).
Barbry, M. et al. Atomistic near-field nanoplasmonics: reaching atomic-scale resolution in nanooptics. Nano Lett. 15, 3410–3419 (2015).
Urbieta, M. et al. Atomic-scale lightning rod effect in plasmonic picocavities: a classical view to a quantum effect. ACS Nano 12, 585–595 (2018).
Carnegie, C. et al. Room-temperature optical picocavities below 1 nm accessing single-atom geometries. J. Phys. Chem. Lett. 9, 7146–7151 (2018).
Hoang, T. B. et al. Ultrafast spontaneous emission source using plasmonic nanoantennas. Nat. Commun. 6, 7788 (2015).
Hoang, T. B., Akselrod, G. M. & Mikkelsen, M. H. Ultrafast room-temperature single photon emission from quantum dots coupled to plasmonic nanocavities. Nano Lett. 16, 270–275 (2016).
Akselrod, G. M. et al. Leveraging nanocavity harmonics for control of optical processes in 2D semiconductors. Nano Lett. 15, 3578–3584 (2015).
Huang, J., Akselrod, G. M., Ming, T., Kong, J. & Mikkelsen, M. H. Tailored emission spectrum of 2D semiconductors using plasmonic nanocavities. ACS Photon. 5, 552–558 (2018).
Rose, A. et al. Control of radiative processes using tunable plasmonic nanopatch antennas. Nano Lett. 14, 4797–4802 (2014).
Akselrod, G. M. et al. Probing the mechanisms of large Purcell enhancement in plasmonic nanoantennas. Nat. Photon. 8, 835–840 (2014).
Chikkaraddy, R. et al. Mapping nanoscale hotspots with single-molecule emitters assembled into plasmonic nanocavities using DNA origami. Nano Lett. 18, 405–411 (2018).
Chikkaraddy, R. et al. Single-molecule strong coupling at room temperature in plasmonic nanocavities. Nature 535, 127–130 (2016).
Kinkhabwala, A. et al. Large single-molecule fluorescence enhancements produced by a bowtie nanoantenna. Nat. Photon. 3, 654–657 (2009).
Akselrod, G. M. et al. Efficient nanosecond photoluminescence from infrared PbS quantum dots coupled to plasmonic nanoantennas. ACS Photon. 3, 1741–1746 (2016).
Argyropoulos, C., Ciracì, C. & Smith, D. R. Enhanced optical bistability with film-coupled plasmonic nanocubes. Appl. Phys. Lett. 104, 63108 (2014).
Kongsuwan, N. et al. Suppressed quenching and strong-coupling of Purcell-enhanced single-molecule emission in plasmonic nanocavities. ACS Photon. 5, 186–191 (2018).
Anger, P., Bharadwaj, P. & Novotny, L. Enhancement and quenching of single-molecule fluorescence. Phys. Rev. Lett. 96, 113002 (2006).
Pelton, M. Modified spontaneous emission in nanophotonic structures. Nat. Photon. 9, 427–435 (2015).
Russell, K. J., Liu, T.-L., Cui, S. & Hu, E. L. Large spontaneous emission enhancement in plasmonic nanocavities. Nat. Photon. 6, 459–462 (2012).
Schlather, A. E., Large, N., Urban, A. S., Nordlander, P. & Halas, N. J. Near-field mediated plexcitonic coupling and giant Rabi splitting in individual metallic dimers. Nano Lett. 13, 3281–3286 (2013).
Kneipp, K. et al. Single molecule detection using surface-enhanced Raman scattering (SERS). Phys. Rev. Lett. 78, 1667–1670 (1997).
Nie, S. Probing single molecules and single nanoparticles by surface-enhanced Raman scattering. Science 275, 1102–1106 (1997).
Qian, X.-M. & Nie, S. M. Single-molecule and single-nanoparticle SERS: from fundamental mechanisms to biomedical applications. Chem. Soc. Rev. 37, 912 (2008).
Sigle, D. O., Hugall, J. T., Ithurria, S., Dubertret, B. & Baumberg, J. J. Probing confined phonon modes in individual cdse nanoplatelets using surface-enhanced Raman scattering. Phys. Rev. Lett. 113, 087402 (2014).
Weiss, A. & Haran, G. Time-dependent single-molecule Raman scattering as a probe of surface dynamics. J. Phys. Chem. B 105, 12348–12354 (2001).
Taylor, R. W. et al. Watching individual molecules flex within lipid membranes using SERS. Sci. Rep. 4, 5940 (2015).
Sonntag, M. D., Chulhai, D., Seideman, T., Jensen, L. & Van Duyne, R. P. The origin of relative intensity fluctuations in single-molecule tip-enhanced Raman spectroscopy. J. Am. Chem. Soc. 135, 17187–17192 (2013).
De Nijs, B. et al. Plasmonic tunnel junctions for single-molecule redox chemistry. Nat. Commun. 8, 994 (2017).
Schmidt, M. K., Esteban, R., Benz, F., Baumberg, J. J. & Aizpurua, J. Linking classical and molecular optomechanics descriptions of SERS. Faraday Discuss. 205, 31–65 (2017).
Roelli, P., Galland, C., Piro, N. & Kippenberg, T. J. Molecular cavity optomechanics as a theory of plasmon-enhanced Raman scattering. Nat. Nanotechnol. 11, 164–169 (2016).
Lombardi, A. et al. Pulsed molecular optomechanics in plasmonic nanocavities: from nonlinear vibrational instabilities to bond-breaking. Phys. Rev. X 8, 011016 (2018).
Mertens, J. et al. Tracking optical welding through groove modes in plasmonic nanocavities. Nano Lett. 16, 5605–5611 (2016).
Di Martino, G., Tappertzhofen, S., Hofmann, S. & Baumberg, J. Nanoscale plasmon-enhanced spectroscopy in memristive switches. Small 12, 1334–1341 (2016).
Emboras, A. et al. Nanoscale plasmonic memristor with optical readout functionality. Nano Lett. 13, 6151–6155 (2013).
Pérez-González, O. et al. Optical spectroscopy of conductive junctions in plasmonic cavities. Nano Lett. 10, 3090–3095 (2010).
Scholl, J. A. et al. Evolution of plasmonic metamolecule modes in the quantum tunneling regime. ACS Nano 10, 1346–1354 (2016).
Lin, L. et al. Nanooptics of plasmonic nanomatryoshkas: shrinking the size of a core–shell junction to subnanometer. Nano Lett. 15, 6419–6428 (2015).
Fontana, J. & Ratna, B. R. Highly tunable gold nanorod dimer resonances mediated through conductive junctions. Appl. Phys. Lett. 105, 011107 (2014).
Herrmann, L. O. et al. Threading plasmonic nanoparticle strings with light. Nat. Commun. 5, 4568 (2014).
Koya, A. N. & Lin, J. Charge transfer plasmons: recent theoretical and experimental developments. Appl. Phys. Rev. 4, 021104 (2017).
Zhu, W. & Crozier, K. B. Quantum mechanical limit to plasmonic enhancement as observed by surface-enhanced Raman scattering. Nat. Commun. 5, 5228 (2014).
Teperik, T. V., Nordlander, P., Aizpurua, J. & Borisov, A. G. Robust subnanometric plasmon ruler by rescaling of the nonlocal optical response. Phys. Rev. Lett. 110, 263901 (2013).
Zhu, W. et al. Quantum mechanical effects in plasmonic structures with subnanometre gaps. Nat. Commun. 7, 11495 (2016).
Readman, C. et al. Anomalously large spectral shifts near the quantum tunnelling limit in plasmonic rulers with subatomic resolution. Nano Lett. https://doi.org/10.1021/acs.nanolett.9b00199 (2019)
Akselrod, G. M. et al. Large-area metasurface perfect absorbers from visible to near-infrared. Adv. Mater. 27, 8028–8034 (2015).
Moreau, A. et al. Controlled-reflectance surfaces with film-coupled colloidal nanoantennas. Nature 492, 86–89 (2012).
Rozin, M. J., Rosen, D. A., Dill, T. J. & Tao, A. R. Colloidal metasurfaces displaying near-ideal and tunable light absorbance in the infrared. Nat. Commun. 6, 7325 (2015).
Brongersma, M. L., Halas, N. J. & Nordlander, P. Plasmon-induced hot carrier science and technology. Nat. Nanotechnol. 10, 25–34 (2015).
Mauser, K. W. et al. Resonant thermoelectric nanophotonics. Nat. Nanotechnol. 12, 770–775 (2017).
Bowen, P. T., Baron, A. & Smith, D. R. Effective-medium description of a metasurface composed of a periodic array of nanoantennas coupled to a metallic film. Phys. Rev. A 95, 033822 (2017).
Stewart, J. W., Akselrod, G. M., Smith, D. R. & Mikkelsen, M. H. Toward multispectral imaging with colloidal metasurface pixels. Adv. Mater. 29, 1602971 (2017).
Goh, X. M. et al. Three-dimensional plasmonic stereoscopic prints in full colour. Nat. Commun. 5, 5361 (2014).
Hoang, T. B. & Mikkelsen, M. H. Broad electrical tuning of plasmonic nanoantennas at visible frequencies. Appl. Phys. Lett. 108, 183107 (2016).
Wilson, W. M., Stewart, J. W. & Mikkelsen, M. H. Surpassing single line width active tuning with photochromic molecules coupled to plasmonic nanoantennas. Nano Lett. 18, 853–858 (2018).
Ding, T., Mertens, J., Sigle, D. O. & Baumberg, J. J. Capillary-force-assisted optical tuning of coupled plasmons. Adv. Mater. 27, 6457–6461 (2015).
Powell, A. W. et al. Plasmonic gas sensing using nanocube patch antennas. Adv. Opt. Mater. 4, 634–642 (2016).
Ding, T. et al. Fast dynamic color switching in temperature-responsive plasmonic films. Adv. Opt. Mater. 4, 877–882 (2016).
Cormier, S., Ding, T., Turek, V. & Baumberg, J. J. Actuating single nano-oscillators with light. Adv. Opt. Mater. 6, 1701281 (2018).
Holsteen, A. L., Raza, S., Fan, P., Kik, P. G. & Brongersma, M. L. Purcell effect for active tuning of light scattering from semiconductor optical antennas. Science 358, 1407–1410 (2017).
Liu, X. et al. Electrical tuning of a quantum plasmonic resonance. Nat. Nanotechnol. 12, 866–870 (2017).
Benz, F. et al. Nanooptics of molecular-shunted plasmonic nanojunctions. Nano Lett. 15, 669–674 (2015).
Tan, S. F. et al. Quantum plasmon resonances controlled by molecular tunnel junctions. Science 343, 1496–1499 (2014).
Kasera, S., Herrmann, L. O., Barrio, J., del, Baumberg, J. J. & Scherman, O. A. Quantitative multiplexing with nano-self-assemblies in SERS. Sci. Rep. 4, 6785 (2015).
Di Martino, G. et al. Tracking nanoelectrochemistry using individual plasmonic nanocavities. Nano Lett. 17, 4840–4845 (2017).
Hoener, B. S. et al. Spectral response of plasmonic gold nanoparticles to capacitive charging: morphology effects. J. Phys. Chem. Lett. 8, 2681–2688 (2017).
Cortés, E. et al. Plasmonic hot electron transport drives nano-localized chemistry. Nat. Commun. 8, 14880 (2017).
Sun, M., Zhang, Z., Zheng, H. & Xu, H. In-situ plasmon-driven chemical reactions revealed by high vacuum tip-enhanced Raman spectroscopy. Sci. Rep. 2, 647 (2012).
van Schrojenstein Lantman, E. M., Deckert-Gaudig, T., Mank, A. J. G., Deckert, V. & Weckhuysen, B. M. Catalytic processes monitored at the nanoscale with tip-enhanced Raman spectroscopy. Nat. Nanotechnol. 7, 583–586 (2012).
Ding, T., Mertens, J., Lombardi, A., Scherman, O. A. & Baumberg, J. J. Light-directed tuning of plasmon resonances via plasmon-induced polymerization using hot electrons. ACS Photon. 4, 1453–1458 (2017).
Peyronel, T., Quirk, K. J., Wang, S. C. & Tiecke, T. G. Luminescent detector for free-space optical communication. Optica 3, 787–792 (2016).
Bogdanov, S. et al. Electron spin contrast of Purcell-enhanced nitrogen-vacancy ensembles in nanodiamonds. Phys. Rev. B 96, 035146 (2017).
Davoyan, A. R. & Atwater, H. A. Quantum nonlinear light emission in metamaterials: broadband Purcell enhancement of parametric downconversion. Optica 5, 608–611 (2018).
Acknowledgements
We acknowledge support from UK EPSRC grants EP/G060649/1, EP/L027151/1, EP/G037221/1, EPSRC NanoDTC, ERC grant LINASS 320503, and FIS2016-80174-P from Spanish Ministry MINECO. M.H.M. acknowledges support from the Air Force Office of Scientific Research (AFOSR, grant no. FA9550‐15‐1‐0301) and the National Science Foundation (DMR-1454523). We appreciate extensive data and discussions on the mode scaling with A. Demetriadou, and enormous contributions from many members of our research groups over the past decade.
Author information
Authors and Affiliations
Contributions
All authors contributed equally to the preparation of this manuscript.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Baumberg, J.J., Aizpurua, J., Mikkelsen, M.H. et al. Extreme nanophotonics from ultrathin metallic gaps. Nat. Mater. 18, 668–678 (2019). https://doi.org/10.1038/s41563-019-0290-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41563-019-0290-y
This article is cited by
-
Synthesized complex-frequency excitation for ultrasensitive molecular sensing
eLight (2024)
-
Extensive photochemical restructuring of molecule-metal surfaces under room light
Nature Communications (2024)
-
Quantum plasmonics pushes chiral sensing limit to single molecules: a paradigm for chiral biodetections
Nature Communications (2024)
-
In situ electrochemical regeneration of nanogap hotspots for continuously reusable ultrathin SERS sensors
Nature Communications (2024)
-
Single-emitter super-resolved imaging of radiative decay rate enhancement in dielectric gap nanoantennas
Light: Science & Applications (2024)