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Richard P Van Duyne - One of the best experts on this subject based on the ideXlab platform.
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unraveling the near and far field relationship of 2d Surface Enhanced Raman spectroscopy substrates using wavelength scan Surface Enhanced Raman excitation spectroscopy
Journal of Physical Chemistry C, 2017Co-Authors: George C Schatz, Dmitry Kurouski, Nicolas Large, Naihao Chiang, Anne Isabelle Henry, Tamar Seideman, Richard P Van DuyneAbstract:Lithographic and nonlithographic two-dimensional (2D) substrates for Surface-Enhanced Raman spectroscopy (SERS) have gained enormous popularity as analytical platforms for detection and identification of various analytes. However, their near- and far-field properties in most cases remain poorly understood. We have previously developed a metal nanopillar film over nanospheres (FON) platform exhibiting Raman enhancement factors of ∼107. These substrates have a reproducible and predictable localized Surface plasmon resonance throughout the entire visible region and much of the near-IR region of the electromagnetic spectrum. Extending upon these results, we have utilized wavelength-scan Surface-Enhanced Raman excitation spectroscopy to unravel the relationship between near- and far-field properties of FON Surface-Enhanced Raman spectroscopy substrates. We examined by scanning electron microscopy FONs fabricated by either stationary (ST-FONs) or spun (SP-FONs) metal deposition to examine the interrelationships...
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ultrafast and nonlinear Surface Enhanced Raman spectroscopy
Chemical Society Reviews, 2016Co-Authors: Natalie L Gruenke, George C Schatz, Fernanda M Cardinal, Michael O Mcanally, Renee R Frontiera, Richard P Van DuyneAbstract:Ultrafast Surface-Enhanced Raman spectroscopy (SERS) has the potential to study molecular dynamics near plasmonic Surfaces to better understand plasmon-mediated chemical reactions such as plasmonically-Enhanced photocatalytic or photovoltaic processes. This review discusses the combination of ultrafast Raman spectroscopic techniques with plasmonic substrates for high temporal resolution, high sensitivity, and high spatial resolution vibrational spectroscopy. First, we introduce background information relevant to ultrafast SERS: the mechanisms of Surface enhancement in Raman scattering, the characterization of plasmonic materials with ultrafast techniques, and early complementary techniques to study molecule–plasmon interactions. We then discuss recent advances in Surface-Enhanced Raman spectroscopies with ultrafast pulses with a focus on the study of molecule–plasmon coupling and molecular dynamics with high sensitivity. We also highlight the challenges faced by this field by the potential damage caused by concentrated, highly energetic pulsed fields in plasmonic hotspots, and finally the potential for future ultrafast SERS studies.
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single molecule Surface Enhanced Raman spectroscopy without nanogaps
Journal of Physical Chemistry Letters, 2013Co-Authors: Alyssa B Zrimsek, Anne Isabelle Henry, Richard P Van DuyneAbstract:We provide conclusive proof of single molecule (SM) detection by Surface-Enhanced Raman spectroscopy (SERS) for discrete Ag triangular nanopyramids prepared via nanosphere lithography (NSL). While the observation of SMSERS has been well-demonstrated using various chemically synthesized nanoparticle substrates, they have a high degree of polydispersity in shape, size, and aggregation state resulting in an interest to develop more reproducible and uniform nanoparticles. Here triangular-based nanopyramids were characterized by scanning electron microscopy to confirm their geometry and interparticle spacing. Then the isotopologue approach with Rhodamine 6G was used to conclusively prove SM sensitivity for the individual nanoparticles. NSL’s straightforward, simple fabrication procedure produces large active arrays. Furthermore, the tunable localized Surface plasmon resonance makes NSL prepared substrates effective for the detection of resonant molecules by SMSERS.
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structure enhancement factor relationships in single gold nanoantennas by Surface Enhanced Raman excitation spectroscopy
Journal of the American Chemical Society, 2013Co-Authors: Samuel L Kleinman, George C Schatz, Anne Isabelle Henry, Griffith R Freeman, Nicholas Valley, Michael J Natan, Bhavya Sharma, Martin G Blaber, Richard P Van DuyneAbstract:Determining the existence of any direct spectral relationship between the far-field scattering properties and the near-field Raman-enhancing properties of Surface-Enhanced Raman spectroscopy (SERS) substrates has been a challenging task with only a few significant results to date. Here, we prove that hot spot dominated systems show little dependence on the far-field scattering properties because of differences between near- and far-field localized Surface plasmon resonance (LSPR) effects as well as excitation of new plasmon modes via a localized emitter. We directly probe the relationship between the near- and far-field light interactions using a correlated LSPR-transmission electron microscopy (TEM) Surface-Enhanced Raman excitation spectroscopy (SERES) technique. Fourteen individual SERS nanoantennas, Au nanoparticle aggregates ranging from dimers to undecamers, coated in a reporter molecule and encased in a protective silica shell, were excited using eight laser wavelengths. We observed no correlation ...
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structure activity relationships in gold nanoparticle dimers and trimers for Surface Enhanced Raman spectroscopy
Journal of the American Chemical Society, 2010Co-Authors: Kristin L Wustholz, George C Schatz, Anne Isabelle Henry, Jeffrey M Mcmahon, Griffith R Freeman, Nicholas Valley, Marcelo Eduardo Piotti, Michael J Natan, Richard P Van DuyneAbstract:Understanding the detailed relationship between nanoparticle structure and activity remains a significant challenge for the field of Surface-Enhanced Raman spectroscopy. To this end, the structural and optical properties of individual plasmonic nanoantennas comprised of Au nanoparticle assemblies that are coated with organic reporter molecules and encapsulated by a SiO2 shell have been determined using correlated transmission electron microscopy (TEM), dark-field Rayleigh scattering microscopy, Surface-Enhanced Raman scattering (SERS) microscopy, and finite element method (FEM) calculations. The distribution of SERS enhancement factors (EFs) for a structurally and optically diverse set of nanoantennas is remarkably narrow. For a collection of 30 individual nanoantennas ranging from dimers to heptamers, the EFs vary by less than 2 orders of magnitude. Furthermore, the EFs for the hot-spot-containing nanoparticles are uncorrelated to aggregation state and localized Surface plasmon resonance (LSPR) wavelengt...
George C Schatz - One of the best experts on this subject based on the ideXlab platform.
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isothermal titration calorimetry for the screening of aflatoxin b1 Surface Enhanced Raman scattering sensor affinity agents
Analytical Chemistry, 2018Co-Authors: Victoria M Szlag, George C Schatz, Seyoung Jung, Rebeca S Rodriguez, Marc R Bourgeois, Samuel Bryson, Theresa M Reineke, Christy L HaynesAbstract:In this work, isothermal titration calorimetry (ITC) is employed as an affinity agent screening method for the Surface-Enhanced Raman scattering (SERS) detection of aflatoxin B1 (AFB1). AFB1, a pot...
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unraveling the near and far field relationship of 2d Surface Enhanced Raman spectroscopy substrates using wavelength scan Surface Enhanced Raman excitation spectroscopy
Journal of Physical Chemistry C, 2017Co-Authors: George C Schatz, Dmitry Kurouski, Nicolas Large, Naihao Chiang, Anne Isabelle Henry, Tamar Seideman, Richard P Van DuyneAbstract:Lithographic and nonlithographic two-dimensional (2D) substrates for Surface-Enhanced Raman spectroscopy (SERS) have gained enormous popularity as analytical platforms for detection and identification of various analytes. However, their near- and far-field properties in most cases remain poorly understood. We have previously developed a metal nanopillar film over nanospheres (FON) platform exhibiting Raman enhancement factors of ∼107. These substrates have a reproducible and predictable localized Surface plasmon resonance throughout the entire visible region and much of the near-IR region of the electromagnetic spectrum. Extending upon these results, we have utilized wavelength-scan Surface-Enhanced Raman excitation spectroscopy to unravel the relationship between near- and far-field properties of FON Surface-Enhanced Raman spectroscopy substrates. We examined by scanning electron microscopy FONs fabricated by either stationary (ST-FONs) or spun (SP-FONs) metal deposition to examine the interrelationships...
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ultrafast and nonlinear Surface Enhanced Raman spectroscopy
Chemical Society Reviews, 2016Co-Authors: Natalie L Gruenke, George C Schatz, Fernanda M Cardinal, Michael O Mcanally, Renee R Frontiera, Richard P Van DuyneAbstract:Ultrafast Surface-Enhanced Raman spectroscopy (SERS) has the potential to study molecular dynamics near plasmonic Surfaces to better understand plasmon-mediated chemical reactions such as plasmonically-Enhanced photocatalytic or photovoltaic processes. This review discusses the combination of ultrafast Raman spectroscopic techniques with plasmonic substrates for high temporal resolution, high sensitivity, and high spatial resolution vibrational spectroscopy. First, we introduce background information relevant to ultrafast SERS: the mechanisms of Surface enhancement in Raman scattering, the characterization of plasmonic materials with ultrafast techniques, and early complementary techniques to study molecule–plasmon interactions. We then discuss recent advances in Surface-Enhanced Raman spectroscopies with ultrafast pulses with a focus on the study of molecule–plasmon coupling and molecular dynamics with high sensitivity. We also highlight the challenges faced by this field by the potential damage caused by concentrated, highly energetic pulsed fields in plasmonic hotspots, and finally the potential for future ultrafast SERS studies.
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structure enhancement factor relationships in single gold nanoantennas by Surface Enhanced Raman excitation spectroscopy
Journal of the American Chemical Society, 2013Co-Authors: Samuel L Kleinman, George C Schatz, Anne Isabelle Henry, Griffith R Freeman, Nicholas Valley, Michael J Natan, Bhavya Sharma, Martin G Blaber, Richard P Van DuyneAbstract:Determining the existence of any direct spectral relationship between the far-field scattering properties and the near-field Raman-enhancing properties of Surface-Enhanced Raman spectroscopy (SERS) substrates has been a challenging task with only a few significant results to date. Here, we prove that hot spot dominated systems show little dependence on the far-field scattering properties because of differences between near- and far-field localized Surface plasmon resonance (LSPR) effects as well as excitation of new plasmon modes via a localized emitter. We directly probe the relationship between the near- and far-field light interactions using a correlated LSPR-transmission electron microscopy (TEM) Surface-Enhanced Raman excitation spectroscopy (SERES) technique. Fourteen individual SERS nanoantennas, Au nanoparticle aggregates ranging from dimers to undecamers, coated in a reporter molecule and encased in a protective silica shell, were excited using eight laser wavelengths. We observed no correlation ...
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structure activity relationships in gold nanoparticle dimers and trimers for Surface Enhanced Raman spectroscopy
Journal of the American Chemical Society, 2010Co-Authors: Kristin L Wustholz, George C Schatz, Anne Isabelle Henry, Jeffrey M Mcmahon, Griffith R Freeman, Nicholas Valley, Marcelo Eduardo Piotti, Michael J Natan, Richard P Van DuyneAbstract:Understanding the detailed relationship between nanoparticle structure and activity remains a significant challenge for the field of Surface-Enhanced Raman spectroscopy. To this end, the structural and optical properties of individual plasmonic nanoantennas comprised of Au nanoparticle assemblies that are coated with organic reporter molecules and encapsulated by a SiO2 shell have been determined using correlated transmission electron microscopy (TEM), dark-field Rayleigh scattering microscopy, Surface-Enhanced Raman scattering (SERS) microscopy, and finite element method (FEM) calculations. The distribution of SERS enhancement factors (EFs) for a structurally and optically diverse set of nanoantennas is remarkably narrow. For a collection of 30 individual nanoantennas ranging from dimers to heptamers, the EFs vary by less than 2 orders of magnitude. Furthermore, the EFs for the hot-spot-containing nanoparticles are uncorrelated to aggregation state and localized Surface plasmon resonance (LSPR) wavelengt...
Jon A Dieringer - One of the best experts on this subject based on the ideXlab platform.
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Surface Enhanced Raman excitation spectroscopy of a single rhodamine 6g molecule
Journal of the American Chemical Society, 2009Co-Authors: Jon A Dieringer, George C Schatz, Jon P Camden, Kristin L Wustholz, David J Masiello, Samuel L Kleinman, Richard P Van DuyneAbstract:The Surface-Enhanced Raman excitation profiles (REPs) of rhodamine 6G (R6G) on Ag Surfaces are studied using a tunable optical parametric oscillator excitation source and versatile detection scheme. These experiments afford the ability to finely tune the excitation wavelength near the molecular resonance of R6G (i.e., approximately 500-575 nm) and perform wavelength-scanned Surface-Enhanced Raman excitation measurements of a single molecule. The ensemble-averaged Surface-Enhanced REPs are measured for collections of molecules on Ag island films. The relative contributions of the 0-0 and 0-1 vibronic transitions to the Surface-Enhanced REPs vary with vibrational frequency. These results highlight the role of excitation energy in determining the resonance Raman intensities for R6G on Surface-enhancing nanostructures. Single-molecule measurements are obtained from individual molecules of R6G on Ag colloidal aggregates, where single-molecule junctions are located using the isotope-edited approach. Overall, single-molecule Surface-Enhanced REPs are narrow in comparison to the ensemble-averaged excitation profiles due to a reduction in inhomogeneous broadening. This work describes the first Raman excitation spectroscopy studies of a single molecule, revealing new information previously obscured by the ensemble.
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Surface Enhanced Raman excitation spectroscopy of a single rhodamine 6g molecule
Journal of the American Chemical Society, 2009Co-Authors: Jon A Dieringer, George C Schatz, Jon P Camden, Kristin L Wustholz, David J Masiello, Samuel L Kleinman, Richard P Van DuyneAbstract:The Surface-Enhanced Raman excitation profiles (REPs) of rhodamine 6G (R6G) on Ag Surfaces are studied using a tunable optical parametric oscillator excitation source and versatile detection scheme. These experiments afford the ability to finely tune the excitation wavelength near the molecular resonance of R6G (i.e., ∼500−575 nm) and perform wavelength-scanned Surface-Enhanced Raman excitation measurements of a single molecule. The ensemble-averaged Surface-Enhanced REPs are measured for collections of molecules on Ag island films. The relative contributions of the 0−0 and 0−1 vibronic transitions to the Surface-Enhanced REPs vary with vibrational frequency. These results highlight the role of excitation energy in determining the resonance Raman intensities for R6G on Surface-enhancing nanostructures. Single-molecule measurements are obtained from individual molecules of R6G on Ag colloidal aggregates, where single-molecule junctions are located using the isotope-edited approach. Overall, single-molecule...
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probing the structure of single molecule Surface Enhanced Raman scattering hot spots
Journal of the American Chemical Society, 2008Co-Authors: Jon P Camden, George C Schatz, Jon A Dieringer, David J Masiello, Yingmin Wang, Lawrence D Marks, Richard P Van DuyneAbstract:We present here a detailed study of the specific nanoparticle structures that give rise to single-molecule Surface-Enhanced Raman scattering (SMSERS). A variety of structures are observed, but the simplest are dimers of Ag nanocrystals. We chose one of these structures for detailed study using electrodynamics calculations and found that the electromagnetic SERS enhancement factors of 109 are easily obtained and are consistent with single-molecule SERS activity.
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Surface Enhanced Raman spectroscopy
Reviews in Analytical Chemistry, 2008Co-Authors: Paul L Stiles, Jon A Dieringer, Nilam C Shah, Richard P Van DuyneAbstract:The ability to control the size, shape, and material of a Surface has reinvigorated the field of Surface-Enhanced Raman spectroscopy (SERS). Because excitation of the localized Surface plasmon resonance of a nanostructured Surface or nanoparticle lies at the heart of SERS, the ability to reliably control the Surface characteristics has taken SERS from an interesting Surface phenomenon to a rapidly developing analytical tool. This article first explains many fundamental features of SERS and then describes the use of nanosphere lithography for the fabrication of highly reproducible and robust SERS substrates. In particular, we review metal film over nanosphere Surfaces as excellent candidates for several experiments that were once impossible with more primitive SERS substrates (e.g., metal island films). The article also describes progress in applying SERS to the detection of chemical warfare agents and several biological molecules.
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wavelength scanned Surface Enhanced Raman excitation spectroscopy
Journal of Physical Chemistry B, 2005Co-Authors: Adam D Mcfarland, Jon A Dieringer, Matthew A Young, Richard P Van DuyneAbstract:A detailed wavelength-scanned Surface-Enhanced Raman excitation spectroscopy (WS SERES) study of benzenethiol adsorbed on Ag nanoparticle arrays, fabricated by nanosphere lithography (NSL), is presented. These NSL-derived Ag nanoparticle array Surfaces are both structurally well-characterized and extremely uniform in size. The WS SERES spectra are correlated, both spatially and spectrally, with the corresponding localized Surface plasmon resonance (LSPR) spectra of the nanoparticle arrays. The Surface-Enhanced Raman scattering (SERS) spectra were measured in two excitation wavelength ranges: (1) 425−505 nm, and (2) 610−800 nm, as well as with the 532-nm line from a solid-state diode-pumped laser. The WS SERES spectra have line shapes similar to those of the LSPR spectra. The maximum SERS enhancement factor is shown to occur for excitation wavelengths that are blue-shifted with respect to the LSPR λmax of adsorbate-covered nanoparticle arrays. Three vibrational modes of benzenethiol (1575, 1081, and 1009 ...
Yu Lu - One of the best experts on this subject based on the ideXlab platform.
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High-density silver nanoparticle film with temperature-controllable interparticle spacing for a tunable Surface Enhanced Raman scattering substrate
Nano Letters, 2005Co-Authors: Yu Lu, Gang L. Liu, Luke P LeeAbstract:Abstract: The formation of high-density silver nanoparticles and a novel method to precisely control the spacing between nanoparticles by temperature are demonstrated for a tunable Surface Enhanced Raman scattering substrates. The high-density nanoparticle thin film is accomplished by self-assembling through the Langmuir-Blodgett (LB) technique on a water Surface and transferring the particle monolayer to a temperature-responsive polymer membrane. The temperature-responsive polymer membrane allows producing a dynamic Surface Enhanced Raman scattering substrate. The plasmon peak of the silver nanoparticle film red shifts up to 110 nm with increasing temperature. The high-density particle film serves as an excellent substrate for Surface-Enhanced Raman spectroscopy (SERS), and the scattering signal enhancement factor can be dynamically tuned by the thermally activated SERS substrate. The SERS spectra of Rhodamine 6G on a high-density silver particle film at various temperatures is characterized to demonstrate the tunable plasmon coupling between high-density nanoparticles.
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high density silver nanoparticle film with temperature controllable interparticle spacing for a tunable Surface Enhanced Raman scattering substrate
Nano Letters, 2005Co-Authors: Yu LuAbstract:The formation of high-density silver nanoparticles and a novel method to precisely control the spacing between nanoparticles by temperature are demonstrated for a tunable Surface Enhanced Raman scattering substrates. The high-density nanoparticle thin film is accomplished by self-assembling through the Langmuir−Blodgett (LB) technique on a water Surface and transferring the particle monolayer to a temperature-responsive polymer membrane. The temperature-responsive polymer membrane allows producing a dynamic Surface Enhanced Raman scattering substrate. The plasmon peak of the silver nanoparticle film red shifts up to 110 nm with increasing temperature. The high-density particle film serves as an excellent substrate for Surface-Enhanced Raman spectroscopy (SERS), and the scattering signal enhancement factor can be dynamically tuned by the thermally activated SERS substrate. The SERS spectra of Rhodamine 6G on a high-density silver particle film at various temperatures is characterized to demonstrate the tun...
Michael S Feld - One of the best experts on this subject based on the ideXlab platform.
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Surface-Enhanced Raman scattering and biophysics
Journal of Physics Condensed Matter, 2002Co-Authors: Katrin Kneipp, Irving Itzkan, Harald Kneipp, Ramachandra R Dasari, Michael S FeldAbstract:Surface-Enhanced Raman scattering (SERS) is a spectroscopic technique which combines modern laser spectroscopy with the exciting optical proper-ties of metallic nanostructures, resulting in strongly increased Raman signals when molecules are attached to nanometre-sized gold and silver structures. The effect provides the structural information content of Raman spectroscopy together with ultrasensitive detection limits, allowing Raman spectroscopy of single molecules. Since SERS takes place in the local fields of metallic nanostructures. the lateral resolution of the technique is determined by the confinement of the local fields, which can be two orders of magnitude better than the diffraction limit. Moreover, SERS is an analytical technique, which can give information on Surface and interface processes.SERS opens up exciting opportunities in the field of biophysical and biomedical spectroscopy, where it provides ultrasensitive detection and characterization of biophysically/biomedically relevant molecules and processes as well as a vibrational spectroscopy with extremely high spatial resolution.The article briefly introduces the SERS effect and reviews contemporary SERS studies in biophysics/biochemistry and in life sciences. Potential and limitations of the technique are briefly discussed.
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extremely large enhancement factors in Surface Enhanced Raman scattering for molecules on colloidal gold clusters
Applied Spectroscopy, 1998Co-Authors: Katrin Kneipp, Harald Kneipp, Ramasamy Manohara, Eugene Hanlo, Irving Itzka, Ramachandra R Dasari, Michael S FeldAbstract:In agreement with previous results reported for colloidal silver clusters, effective Surface-Enhanced Raman cross sections of about 10-16 cm2 per molecule, corresponding to enhancement factors on the order of 10 14, have also been obtained for molecules attached to colloidal gold clusters. Spatially isolated nearly spherical colloidal gold particles of about 60 nm size show maximum enhancement factors on the order of 103 at 514 nm excitation, close to the single plasmon resonance. The enhancement factor increases by eleven orders of magnitude when colloidal gold clusters are formed by aggregation of the gold colloids and when near-infrared excitation is applied. The large effective Surface-Enhanced Raman cross section has been estimated by a straightforward method based on steady-state population redistribution due to the pumping of molecules to the first excited vibrational state via the strongly Enhanced Raman process. Our experimental finding confirms the important role of colloidal clusters for extremely large Surface-Enhanced Raman scattering (SERS) enhancement factors. Simultaneously, it suggests colloidal gold clusters as a substrate for high-sensitivity Surface-Enhanced Raman scattering, which can provide an enhancement level sufficient for Raman single molecule detection. Due to its chemical inactivity, gold might have some advantages compared to silver, particularly in biomedical spectroscopy.
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detection and identification of a single dna base molecule using Surface Enhanced Raman scattering sers
Physical Review E, 1998Co-Authors: Katrin Kneipp, Irving Itzkan, Harald Kneipp, Ramachandra R Dasari, Bhaskaran V Kartha, Ramasamy Manoharan, Geurt Deinum, Michael S FeldAbstract:Nonresonant Raman cross sections of ~10 -16 cm 2 per molecule are shown to be related to Surface-Enhanced Raman scattering (SERS) on colloidal silver clusters at near-infrared (NIR) excitation. The enhancement is found to be independent of cluster sizes between 100 nm and 20 μm. These experimental findings demonstrate that NIR SERS on colloidal silver clusters is an excellent technique for single molecule detection that is applicable for a broad range of molecules including "colorless" biomolecules, for example nucleotides in DNA sequencing. As an example, we present the detection of a single adenine molecule without any labeling based on its intrinsic Surface-Enhanced Raman scattering.
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detection and identification of a single dna base molecule using Surface Enhanced Raman scattering sers
Physical Review E, 1998Co-Authors: Katrin Kneipp, Irving Itzkan, Harald Kneipp, Ramachandra R Dasari, Bhaskaran V Kartha, Ramasamy Manoharan, Geurt Deinum, Michael S FeldAbstract:Nonresonant Raman cross sections of $\ensuremath{\sim}{10}^{\ensuremath{-}16} {\mathrm{cm}}^{2}$ per molecule are shown to be related to Surface-Enhanced Raman scattering (SERS) on colloidal silver clusters at near-infrared (NIR) excitation. The enhancement is found to be independent of cluster sizes between 100 nm and 20 \ensuremath{\mu}m. These experimental findings demonstrate that NIR SERS on colloidal silver clusters is an excellent technique for single molecule detection that is applicable for a broad range of molecules including ``colorless'' biomolecules, for example nucleotides in DNA sequencing. As an example, we present the detection of a single adenine molecule without any labeling based on its intrinsic Surface-Enhanced Raman scattering.
