Editorial pubs.acs.org/JPCL
Nanoparticles at SEA: Seeding, Etching, and Applications
U
different processes29 and how the size and shape of the nanoparticles can be manipulated to control the dephasing times and energy relaxation processes.32−35 The plasmon dephasing times can be measured by single-particle experiments,32,36 which have been the subject of several previous Perspectives in The Journal of Physical Chemistry Letters.37,38
nderstanding, manipulating, and exploiting the properties of nanomaterials is a major area of research in physical chemistry.1,2 On the experimental side, progress in this field of science requires access to high-quality samples. For spherical particles, a variety of reliable recipes are available. For example, high-quality gold nanoparticles with sizes between 10 and a few hundred nanometers can be made using recipes developed over 50 years ago.3 These materials are used in applications ranging from molecular sensing to biological imaging.4−6 The rise of nanoscience as a discipline was also, in no small part, due to the development of hot-injection methods to make high-quality quantum dot samples.7 However, it is harder to make nonspherical particles while maintaining good control over size dispersion.1,8 The Perspectives by Burrows et al.9 and Christesen et al.10 discuss recent developments in creating anisotropic nanoparticles with complex morphologies. The article by Burrows et al. provides an overview of wet chemistry synthetic methods to create anisotropic nanoparticles, with an emphasis on seed-mediated growth of nanorods.11,12 By controlling parameters such as the pH, the concentrations of the seeds and precursors, the solvent, the temperature, the capping ligands, and the counterions, researchers can now make materials with a wide variety of different shapes, including nanorods,7,11 nanostars,13 cubes,1 nanowires,14−16 triangles,17 plates,18 and octopods.19,20 These materials have interesting optical and catalytic properties. Advances in methods to selectively functionalize specific regions of the particle are also discussed in ref 9, as well as the way surface functionalization can be used to control self-assembly of the particles into superstructures, such as rings.21,22 On the other hand, Christesen et al. discuss a very different way of creating nanostructures with complex morphologies.10,23 In their work, Si nanowires are grown with varying dopant (phosphorus) concentrations using a vapor−liquid−solid (VLS) scheme. Exposure to a KOH solution selectively etches the undoped regions of the nanowires.24−26 By carefully controlling the doping and etching conditions, features can be created with approximately 10 nm spatial resolution. These features are naturally radially symmetric; however, this is not a significant restriction or problem for most applications of nanowires. Thermally oxidizing the nanowires provides an additional control parameter and allows the creation of Si quantum dots along the nanowires with precisely controlled spacings.10 The extension of these techniques to other materials beyond Si is also discussed. One of the main applications of anisotropic nanoparticles has been in plasmonics, to create field enhancements at specific wavelengths.4 These enhancements are extremely useful for surface spectroscopies6,27 and have recently been used to improve the performance of solar cells.28 The Perspective by Cushing and Wu discusses the different ways plasmonic nanoparticles can be used to increase solar cell efficiencies.29 The mechanisms discussed include light trapping,30 hot electron and hole injection,31 and energy transfer. The focus of the article is on how the plasmon dephasing affects these © 2016 American Chemical Society
Gregory V. Hartland, Senior Editor
■
University of Notre Dame, Notre Dame, Indiana 46556, United States
AUTHOR INFORMATION
Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS.
■
REFERENCES
(1) Sun, Y. G.; Xia, Y. N. Shape-Controlled Synthesis of Gold and Silver Nanoparticles. Science 2002, 298, 2176−2179. (2) Kamat, P. V. Meeting the Clean Energy Demand: Nanostructure Architectures for Solar Energy Conversion. J. Phys. Chem. C 2007, 111, 2834−2860. (3) Frens, G. Controlled Nucleation for Regulation of Particle-Size in Monodisperse Gold Suspensions. Nature, Phys. Sci. 1973, 241, 20−22. (4) Lal, S.; Link, S.; Halas, N. J. Nano-Optics from Sensing to Waveguiding. Nat. Photonics 2007, 1, 641−648. (5) Jain, P. K.; Huang, X. H.; El-Sayed, I. H.; El-Sayed, M. A. Noble Metals on the Nanoscale: Optical and Photothermal Properties and Some Applications in Imaging, Sensing, Biology, and Medicine. Acc. Chem. Res. 2008, 41, 1578−1586. (6) Tao, A. R.; Habas, S.; Yang, P. D. Shape Control of Colloidal Metal Nanocrystals. Small 2008, 4, 310−325. (7) Murray, C. B.; Norris, D. J.; Bawendi, M. G. Synthesis and Characterization of Nearly Monodisperse Cde (E = S, Se, Te) Semiconductor Nanocrystallites. J. Am. Chem. Soc. 1993, 115, 8706− 8715. (8) Alivisatos, A. P.; et al. Shape Control of Cdse Nanocrystals. Nature 2000, 404, 59−61. (9) Burrows, N. D.; Vartanian, A. M.; Abadeer, N. S.; Grzincic, E. M.; Jacob, L. M.; Lin, W.; Li, J.; Dennison, J. M.; Hinman, J. G.; Murphy, C. J. Anisotropic Nanoparticles and Anisotropic Surface Chemistry. J. Phys. Chem. Lett. 2016, 7, 632−641. (10) Christesen, J. D.; Pinion, C. W.; Hill, D. J.; Kim, S.; Cahoon, J. F. Chemically Engraving Semiconductor Nanowires: Using ThreeDimensional Nanoscale Morphology to Encode Functionality from the Bottom Up. J. Phys. Chem. Lett. 2016, 7, 685−692. (11) Jana, N. R.; Gearheart, L.; Murphy, C. J. Wet Chemical Synthesis of High Aspect Ratio Cylindrical Gold Nanorods. J. Phys. Chem. B 2001, 105, 4065−4067. (12) Murphy, C. J.; Sau, T. K.; Gole, A. M.; Orendorff, C. J.; Gao, J. X.; Gou, L.; Hunyadi, S. E.; Li, T. Anisotropic Metal Nanoparticles: Synthesis, Assembly, and Optical Applications. J. Phys. Chem. B 2005, 109, 13857−13870. (13) Senthil Kumar, P.; Pastoriza-Santos, I.; Rodriguez-Gonzalez, B.; Garcia de Abajo, F. J.; Liz-Marzan, L. M. High-Yield Synthesis and Optical Response of Gold Nanostars. Nanotechnology 2008, 19, 015606. Published: February 18, 2016 728
DOI: 10.1021/acs.jpclett.6b00048 J. Phys. Chem. Lett. 2016, 7, 728−729
The Journal of Physical Chemistry Letters
Editorial
Electron-Phonon Scattering in Metal Clusters. Phys. Rev. Lett. 2003, 90, 177401. (36) Crut, A.; Maioli, P.; Del Fatti, N.; Vallee, F. Optical Absorption and Scattering Spectroscopies of Single Nano-Objects. Chem. Soc. Rev. 2014, 43, 3921−3956. (37) Slaughter, L.; Chang, W. S.; Link, S. Characterizing Plasmons in Nanoparticles and Their Assemblies with Single Particle Spectroscopy. J. Phys. Chem. Lett. 2011, 2, 2015−2023. (38) Okamoto, H.; Imura, K. Visualizing the Optical Field Structures in Metal Nanostructures. J. Phys. Chem. Lett. 2013, 4, 2230−2241.
(14) Sun, Y. G.; Xia, Y. N. Large-Scale Synthesis of Uniform Silver Nanowires through a Soft, Self-Seeding, Polyol Process. Adv. Mater. 2002, 14, 833−837. (15) Xia, Y. N.; Yang, P. D.; Sun, Y. G.; Wu, Y. Y.; Mayers, B.; Gates, B.; Yin, Y. D.; Kim, F.; Yan, Y. Q. One-Dimensional Nanostructures: Synthesis, Characterization, and Applications. Adv. Mater. 2003, 15, 353−389. (16) Khanal, B. P.; Zubarev, E. R. Purification of High Aspect Ratio Gold Nanorods: Complete Removal of Platelets. J. Am. Chem. Soc. 2008, 130, 12634. (17) Jin, R. C.; Cao, Y. W.; Mirkin, C. A.; Kelly, K. L.; Schatz, G. C.; Zheng, J. G. Photoinduced Conversion of Silver Nanospheres to Nanoprisms. Science 2001, 294, 1901−1903. (18) Xiong, Y. J.; Washio, I.; Chen, J. Y.; Cai, H. G.; Li, Z. Y.; Xia, Y. N. Poly(Vinyl Pyrrolidone): A Dual Functional Reductant and Stabilizer for the Facile Synthesis of Noble Metal Nanoplates in Aqueous Solutions. Langmuir 2006, 22, 8563−8570. (19) DeSantis, C. J.; Peverly, A. A.; Peters, D. G.; Skrabalak, S. E. Octopods Versus Concave Nanocrystals: Control of Morphology by Manipulating the Kinetics of Seeded Growth Via Co-Reduction. Nano Lett. 2011, 11, 2164−2168. (20) DeSantis, C. J.; Sue, A. C.; Bower, M. M.; Skrabalak, S. E. SeedMediated Co-Reduction: A Versatile Route to Architecturally Controlled Bimetallic Nanostructures. ACS Nano 2012, 6, 2617−2628. (21) Khanal, B. P.; Zubarev, E. R. Rings of Nanorods. Angew. Chem., Int. Ed. 2007, 46, 2195−2198. (22) Nie, Z. H.; Fava, D.; Rubinstein, M.; Kumacheva, E. ″Supramolecular″ Assembly of Gold Nanorods End-Terminated with Polymer ″Pom-Poms″: Effect of Pom-Pom Structure on the Association Modes. J. Am. Chem. Soc. 2008, 130, 3683−3689. (23) Musin, I. R.; Boyuk, D. S.; Filler, M. A. Surface Chemistry Controlled Diameter-Modulated Semiconductor Nanowire Superstructures. J. Vac. Sci. Technol., B 2013, 31, 020603. (24) Chou, L. W.; Boyuk, D. S.; Filler, M. A. Optically Abrupt Localized Surface Plasmon Resonances in Si Nanowires by Mitigation of Carrier Density Gradients. ACS Nano 2015, 9, 1250−1256. (25) Christesen, J. D.; Pinion, C. W.; Grumstrup, E. M.; Papanikolas, J. M.; Cahoon, J. F. Synthetically Encoding 10 Nm Morphology in Silicon Nanowires. Nano Lett. 2013, 13, 6281−6286. (26) Christesen, J. D.; Pinion, C. W.; Zhang, X.; McBride, J. R.; Cahoon, J. F. Encoding Abrupt and Uniform Dopant Profiles in Vapor-Liquid-Solid Nanowires by Suppressing the Reservoir Effect of the Liquid Catalyst. ACS Nano 2014, 8, 11790−11798. (27) Willets, K. A.; Van Duyne, R. P. Localized Surface Plasmon Resonance Spectroscopy and Sensing. Annu. Rev. Phys. Chem. 2007, 58, 267−297. (28) Atwater, H. A.; Polman, A. Plasmonics for Improved Photovoltaic Devices. Nat. Mater. 2010, 9, 205−213. (29) Cushing, S. K.; Wu, N. Progress and Perspectives of PlasmonEnhanced Solar Energy Conversion. J. Phys. Chem. Lett. 2016, 7, 666− 675. (30) Spinelli, P.; Ferry, V. E.; van de Groep, J.; van Lare, M.; Verschuuren, M. A.; Schropp, R. E. I.; Atwater, H. A.; Polman, A. Plasmonic Light Trapping in Thin-Film Si Solar Cells. J. Opt. 2012, 14, 024002. (31) Govorov, A. O.; Zhang, H.; Gun’ko, Y. K. Theory of Photoinjection of Hot Plasmonic Carriers from Metal Nanostructures into Semiconductors and Surface Molecules. J. Phys. Chem. C 2013, 117, 16616−16631. (32) Hartland, G. V. Optical Studies of Dynamics in Noble Metal Nanostructures. Chem. Rev. 2011, 111, 3858−3887. (33) Voisin, C.; Christofilos, D.; Del Fatti, N.; Vallee, F.; Prevel, B.; Cottancin, E.; Lerme, J.; Pellarin, M.; Broyer, M. Size-Dependent Electron-Electron Interactions in Metal Nanoparticles. Phys. Rev. Lett. 2000, 85, 2200−2203. (34) Sonnichsen, C.; Franzl, T.; Wilk, T.; von Plessen, G.; Feldmann, J.; Wilson, O.; Mulvaney, P. Drastic Reduction of Plasmon Damping in Gold Nanorods. Phys. Rev. Lett. 2002, 88, 077402. (35) Arbouet, A.; Voisin, C.; Christofilos, D.; Langot, P.; Del Fatti, N.; Vallee, F.; Lerme, J.; Celep, G.; Cottancin, E.; Gaudry, M.; et al. 729
DOI: 10.1021/acs.jpclett.6b00048 J. Phys. Chem. Lett. 2016, 7, 728−729
Nanoparticles at SEA: Seeding, Etching, and Applications
U
different processes29 and how the size and shape of the nanoparticles can be manipulated to control the dephasing times and energy relaxation processes.32−35 The plasmon dephasing times can be measured by single-particle experiments,32,36 which have been the subject of several previous Perspectives in The Journal of Physical Chemistry Letters.37,38
nderstanding, manipulating, and exploiting the properties of nanomaterials is a major area of research in physical chemistry.1,2 On the experimental side, progress in this field of science requires access to high-quality samples. For spherical particles, a variety of reliable recipes are available. For example, high-quality gold nanoparticles with sizes between 10 and a few hundred nanometers can be made using recipes developed over 50 years ago.3 These materials are used in applications ranging from molecular sensing to biological imaging.4−6 The rise of nanoscience as a discipline was also, in no small part, due to the development of hot-injection methods to make high-quality quantum dot samples.7 However, it is harder to make nonspherical particles while maintaining good control over size dispersion.1,8 The Perspectives by Burrows et al.9 and Christesen et al.10 discuss recent developments in creating anisotropic nanoparticles with complex morphologies. The article by Burrows et al. provides an overview of wet chemistry synthetic methods to create anisotropic nanoparticles, with an emphasis on seed-mediated growth of nanorods.11,12 By controlling parameters such as the pH, the concentrations of the seeds and precursors, the solvent, the temperature, the capping ligands, and the counterions, researchers can now make materials with a wide variety of different shapes, including nanorods,7,11 nanostars,13 cubes,1 nanowires,14−16 triangles,17 plates,18 and octopods.19,20 These materials have interesting optical and catalytic properties. Advances in methods to selectively functionalize specific regions of the particle are also discussed in ref 9, as well as the way surface functionalization can be used to control self-assembly of the particles into superstructures, such as rings.21,22 On the other hand, Christesen et al. discuss a very different way of creating nanostructures with complex morphologies.10,23 In their work, Si nanowires are grown with varying dopant (phosphorus) concentrations using a vapor−liquid−solid (VLS) scheme. Exposure to a KOH solution selectively etches the undoped regions of the nanowires.24−26 By carefully controlling the doping and etching conditions, features can be created with approximately 10 nm spatial resolution. These features are naturally radially symmetric; however, this is not a significant restriction or problem for most applications of nanowires. Thermally oxidizing the nanowires provides an additional control parameter and allows the creation of Si quantum dots along the nanowires with precisely controlled spacings.10 The extension of these techniques to other materials beyond Si is also discussed. One of the main applications of anisotropic nanoparticles has been in plasmonics, to create field enhancements at specific wavelengths.4 These enhancements are extremely useful for surface spectroscopies6,27 and have recently been used to improve the performance of solar cells.28 The Perspective by Cushing and Wu discusses the different ways plasmonic nanoparticles can be used to increase solar cell efficiencies.29 The mechanisms discussed include light trapping,30 hot electron and hole injection,31 and energy transfer. The focus of the article is on how the plasmon dephasing affects these © 2016 American Chemical Society
Gregory V. Hartland, Senior Editor
■
University of Notre Dame, Notre Dame, Indiana 46556, United States
AUTHOR INFORMATION
Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS.
■
REFERENCES
(1) Sun, Y. G.; Xia, Y. N. Shape-Controlled Synthesis of Gold and Silver Nanoparticles. Science 2002, 298, 2176−2179. (2) Kamat, P. V. Meeting the Clean Energy Demand: Nanostructure Architectures for Solar Energy Conversion. J. Phys. Chem. C 2007, 111, 2834−2860. (3) Frens, G. Controlled Nucleation for Regulation of Particle-Size in Monodisperse Gold Suspensions. Nature, Phys. Sci. 1973, 241, 20−22. (4) Lal, S.; Link, S.; Halas, N. J. Nano-Optics from Sensing to Waveguiding. Nat. Photonics 2007, 1, 641−648. (5) Jain, P. K.; Huang, X. H.; El-Sayed, I. H.; El-Sayed, M. A. Noble Metals on the Nanoscale: Optical and Photothermal Properties and Some Applications in Imaging, Sensing, Biology, and Medicine. Acc. Chem. Res. 2008, 41, 1578−1586. (6) Tao, A. R.; Habas, S.; Yang, P. D. Shape Control of Colloidal Metal Nanocrystals. Small 2008, 4, 310−325. (7) Murray, C. B.; Norris, D. J.; Bawendi, M. G. Synthesis and Characterization of Nearly Monodisperse Cde (E = S, Se, Te) Semiconductor Nanocrystallites. J. Am. Chem. Soc. 1993, 115, 8706− 8715. (8) Alivisatos, A. P.; et al. Shape Control of Cdse Nanocrystals. Nature 2000, 404, 59−61. (9) Burrows, N. D.; Vartanian, A. M.; Abadeer, N. S.; Grzincic, E. M.; Jacob, L. M.; Lin, W.; Li, J.; Dennison, J. M.; Hinman, J. G.; Murphy, C. J. Anisotropic Nanoparticles and Anisotropic Surface Chemistry. J. Phys. Chem. Lett. 2016, 7, 632−641. (10) Christesen, J. D.; Pinion, C. W.; Hill, D. J.; Kim, S.; Cahoon, J. F. Chemically Engraving Semiconductor Nanowires: Using ThreeDimensional Nanoscale Morphology to Encode Functionality from the Bottom Up. J. Phys. Chem. Lett. 2016, 7, 685−692. (11) Jana, N. R.; Gearheart, L.; Murphy, C. J. Wet Chemical Synthesis of High Aspect Ratio Cylindrical Gold Nanorods. J. Phys. Chem. B 2001, 105, 4065−4067. (12) Murphy, C. J.; Sau, T. K.; Gole, A. M.; Orendorff, C. J.; Gao, J. X.; Gou, L.; Hunyadi, S. E.; Li, T. Anisotropic Metal Nanoparticles: Synthesis, Assembly, and Optical Applications. J. Phys. Chem. B 2005, 109, 13857−13870. (13) Senthil Kumar, P.; Pastoriza-Santos, I.; Rodriguez-Gonzalez, B.; Garcia de Abajo, F. J.; Liz-Marzan, L. M. High-Yield Synthesis and Optical Response of Gold Nanostars. Nanotechnology 2008, 19, 015606. Published: February 18, 2016 728
DOI: 10.1021/acs.jpclett.6b00048 J. Phys. Chem. Lett. 2016, 7, 728−729
The Journal of Physical Chemistry Letters
Editorial
Electron-Phonon Scattering in Metal Clusters. Phys. Rev. Lett. 2003, 90, 177401. (36) Crut, A.; Maioli, P.; Del Fatti, N.; Vallee, F. Optical Absorption and Scattering Spectroscopies of Single Nano-Objects. Chem. Soc. Rev. 2014, 43, 3921−3956. (37) Slaughter, L.; Chang, W. S.; Link, S. Characterizing Plasmons in Nanoparticles and Their Assemblies with Single Particle Spectroscopy. J. Phys. Chem. Lett. 2011, 2, 2015−2023. (38) Okamoto, H.; Imura, K. Visualizing the Optical Field Structures in Metal Nanostructures. J. Phys. Chem. Lett. 2013, 4, 2230−2241.
(14) Sun, Y. G.; Xia, Y. N. Large-Scale Synthesis of Uniform Silver Nanowires through a Soft, Self-Seeding, Polyol Process. Adv. Mater. 2002, 14, 833−837. (15) Xia, Y. N.; Yang, P. D.; Sun, Y. G.; Wu, Y. Y.; Mayers, B.; Gates, B.; Yin, Y. D.; Kim, F.; Yan, Y. Q. One-Dimensional Nanostructures: Synthesis, Characterization, and Applications. Adv. Mater. 2003, 15, 353−389. (16) Khanal, B. P.; Zubarev, E. R. Purification of High Aspect Ratio Gold Nanorods: Complete Removal of Platelets. J. Am. Chem. Soc. 2008, 130, 12634. (17) Jin, R. C.; Cao, Y. W.; Mirkin, C. A.; Kelly, K. L.; Schatz, G. C.; Zheng, J. G. Photoinduced Conversion of Silver Nanospheres to Nanoprisms. Science 2001, 294, 1901−1903. (18) Xiong, Y. J.; Washio, I.; Chen, J. Y.; Cai, H. G.; Li, Z. Y.; Xia, Y. N. Poly(Vinyl Pyrrolidone): A Dual Functional Reductant and Stabilizer for the Facile Synthesis of Noble Metal Nanoplates in Aqueous Solutions. Langmuir 2006, 22, 8563−8570. (19) DeSantis, C. J.; Peverly, A. A.; Peters, D. G.; Skrabalak, S. E. Octopods Versus Concave Nanocrystals: Control of Morphology by Manipulating the Kinetics of Seeded Growth Via Co-Reduction. Nano Lett. 2011, 11, 2164−2168. (20) DeSantis, C. J.; Sue, A. C.; Bower, M. M.; Skrabalak, S. E. SeedMediated Co-Reduction: A Versatile Route to Architecturally Controlled Bimetallic Nanostructures. ACS Nano 2012, 6, 2617−2628. (21) Khanal, B. P.; Zubarev, E. R. Rings of Nanorods. Angew. Chem., Int. Ed. 2007, 46, 2195−2198. (22) Nie, Z. H.; Fava, D.; Rubinstein, M.; Kumacheva, E. ″Supramolecular″ Assembly of Gold Nanorods End-Terminated with Polymer ″Pom-Poms″: Effect of Pom-Pom Structure on the Association Modes. J. Am. Chem. Soc. 2008, 130, 3683−3689. (23) Musin, I. R.; Boyuk, D. S.; Filler, M. A. Surface Chemistry Controlled Diameter-Modulated Semiconductor Nanowire Superstructures. J. Vac. Sci. Technol., B 2013, 31, 020603. (24) Chou, L. W.; Boyuk, D. S.; Filler, M. A. Optically Abrupt Localized Surface Plasmon Resonances in Si Nanowires by Mitigation of Carrier Density Gradients. ACS Nano 2015, 9, 1250−1256. (25) Christesen, J. D.; Pinion, C. W.; Grumstrup, E. M.; Papanikolas, J. M.; Cahoon, J. F. Synthetically Encoding 10 Nm Morphology in Silicon Nanowires. Nano Lett. 2013, 13, 6281−6286. (26) Christesen, J. D.; Pinion, C. W.; Zhang, X.; McBride, J. R.; Cahoon, J. F. Encoding Abrupt and Uniform Dopant Profiles in Vapor-Liquid-Solid Nanowires by Suppressing the Reservoir Effect of the Liquid Catalyst. ACS Nano 2014, 8, 11790−11798. (27) Willets, K. A.; Van Duyne, R. P. Localized Surface Plasmon Resonance Spectroscopy and Sensing. Annu. Rev. Phys. Chem. 2007, 58, 267−297. (28) Atwater, H. A.; Polman, A. Plasmonics for Improved Photovoltaic Devices. Nat. Mater. 2010, 9, 205−213. (29) Cushing, S. K.; Wu, N. Progress and Perspectives of PlasmonEnhanced Solar Energy Conversion. J. Phys. Chem. Lett. 2016, 7, 666− 675. (30) Spinelli, P.; Ferry, V. E.; van de Groep, J.; van Lare, M.; Verschuuren, M. A.; Schropp, R. E. I.; Atwater, H. A.; Polman, A. Plasmonic Light Trapping in Thin-Film Si Solar Cells. J. Opt. 2012, 14, 024002. (31) Govorov, A. O.; Zhang, H.; Gun’ko, Y. K. Theory of Photoinjection of Hot Plasmonic Carriers from Metal Nanostructures into Semiconductors and Surface Molecules. J. Phys. Chem. C 2013, 117, 16616−16631. (32) Hartland, G. V. Optical Studies of Dynamics in Noble Metal Nanostructures. Chem. Rev. 2011, 111, 3858−3887. (33) Voisin, C.; Christofilos, D.; Del Fatti, N.; Vallee, F.; Prevel, B.; Cottancin, E.; Lerme, J.; Pellarin, M.; Broyer, M. Size-Dependent Electron-Electron Interactions in Metal Nanoparticles. Phys. Rev. Lett. 2000, 85, 2200−2203. (34) Sonnichsen, C.; Franzl, T.; Wilk, T.; von Plessen, G.; Feldmann, J.; Wilson, O.; Mulvaney, P. Drastic Reduction of Plasmon Damping in Gold Nanorods. Phys. Rev. Lett. 2002, 88, 077402. (35) Arbouet, A.; Voisin, C.; Christofilos, D.; Langot, P.; Del Fatti, N.; Vallee, F.; Lerme, J.; Celep, G.; Cottancin, E.; Gaudry, M.; et al. 729
DOI: 10.1021/acs.jpclett.6b00048 J. Phys. Chem. Lett. 2016, 7, 728−729
