The Experts below are selected from a list of 1734 Experts worldwide ranked by ideXlab platform
Robert M. Corn - One of the best experts on this subject based on the ideXlab platform.
-
Lithographically Patterned Electrodeposition of Gold, Silver, and Nickel Nanoring Arrays with Widely Tunable Near-Infrared Plasmonic Resonances
2016Co-Authors: Aaron R Halpern, Robert M. CornAbstract:A novel low-cost Nanoring array fabrication method that combines the process of lithographically patterned nanoscale electrodeposition (LPNE) with colloidal lithography is described. Nanoring array fabrication was accomplished in three steps: (i) a thin (70 nm) sacrificial nickel or silver film was first vapor-deposited onto a plasma-etched packed colloidal monolayer; (ii) the polymer colloids were removed from the surface, a thin film of positive photoresist was applied, and a backside exposure of the photoresist was used to create a nanohole electrode array; (iii) this array of nanoscale cylindrical electrodes was then used for the electrodeposition of gold, silver, or nickel Nanorings. Removal of the photoresist and sacrificial metal film yielded a Nanoring array in which all of the Nanoring dimensions were set independently: the inter-ring spacing was fixed by the colloidal radius, the radius of the Nanorings was controlled by the plasma etching process, and the width of the Nanorings was controlled by the electrodeposition process. A combination of scanning electron microscopy (SEM) measurements and Fourier transform near-infrared (FT-NIR) absorption spectroscopy were used to characterize the Nanoring arrays. Nanoring arrays with radii from 200 to 400 nm exhibited a single strong NIR plasmonic resonance with an absorption maximum wavelength that varied linearly from 1.25 to 3.33 μm as predicted by a simple standing wave model linear antenna theory. This simple yet versatile Nanoring array fabrication method was also used to electrodeposit concentric double gold Nanoring arrays that exhibited multiple NIR plasmonic resonances
-
lithographically patterned nanoscale electrodeposition of plasmonic bimetallic semiconductor magnetic and polymer Nanoring arrays
Journal of Physical Chemistry C, 2014Co-Authors: Kyunghee Cho, Gabriel Loget, Robert M. CornAbstract:Large area arrays of magnetic, semiconducting, and insulating Nanorings were created by coupling colloidal lithography with nanoscale electrodeposition. This versatile nanoscale fabrication process allows for the independent tuning of the spacing, diameter, and width of the Nanorings with typical values of 1.0 μm, 750 nm, and 100 nm, respectively, and was used to form Nanorings from a host of materials: Ni, Co, bimetallic Ni/Au, CdSe, and polydopamine. These Nanoring arrays have potential applications in memory storage, optical materials, and biosensing. A modified version of this nanoscale electrodeposition process was also used to create arrays of split gold Nanorings. The size of the split Nanoring opening was controlled by the angle of photoresist exposure during the fabrication process and could be varied from 50% down to 10% of the ring circumference. The large area (cm2 scale) gold split Nanoring array surfaces exhibited strong polarization-dependent plasmonic absorption bands for wavelengths from ...
-
Gold Nanoring Arrays for Near Infrared Plasmonic Biosensing
Plasmonics, 2013Co-Authors: Mana Toma, Jennifer B. Wood, Robert M. CornAbstract:Gold Nanoring array surfaces that exhibit strong localized surface plasmon resonances (LSPR) at near infrared (NIR) wavelengths from 1.1 to 1.6 μm were used as highly sensitive real-time refractive index biosensors. Arrays of gold Nanorings with tunable diameter, width, and spacing were created by the nanoscale electrodeposition of gold Nanorings onto lithographically patterned nanohole array conductive surfaces over large areas (square centimeters). The bulk refractive index sensitivity of the gold Nanoring arrays was determined to be up to 3,780 cm−1/refractive index unit by monitoring shifts in the LSPR peak by FT-NIR transmittance spectroscopy measurements. As a first application, the surface polymerization reaction of dopamine to form polydopamine thin films on the Nanoring sensor surface from aqueous solution was monitored with the real-time LSPR peak shift measurements. To demonstrate the utility of the gold Nanoring arrays for LSPR biosensing, the hybridization adsorption of DNA-functionalized gold nanoparticles onto complementary DNA-functionalized gold Nanoring arrays was monitored. The adsorption of DNA-modified gold nanoparticles onto Nanoring arrays modified with mixed DNA monolayers that contained only 0.5 % complementary DNA was also detected; this relative surface coverage corresponds to the detection of DNA by hybridization adsorption from a 50 pM solution.
-
lithographically patterned electrodeposition of gold silver and nickel Nanoring arrays with widely tunable near infrared plasmonic resonances
ACS Nano, 2013Co-Authors: Aaron R Halpern, Robert M. CornAbstract:A novel low-cost Nanoring array fabrication method that combines the process of lithographically patterned nanoscale electrodeposition (LPNE) with colloidal lithography is described. Nanoring array fabrication was accomplished in three steps: (i) a thin (70 nm) sacrificial nickel or silver film was first vapor-deposited onto a plasma-etched packed colloidal monolayer; (ii) the polymer colloids were removed from the surface, a thin film of positive photoresist was applied, and a backside exposure of the photoresist was used to create a nanohole electrode array; (iii) this array of nanoscale cylindrical electrodes was then used for the electrodeposition of gold, silver, or nickel Nanorings. Removal of the photoresist and sacrificial metal film yielded a Nanoring array in which all of the Nanoring dimensions were set independently: the inter-ring spacing was fixed by the colloidal radius, the radius of the Nanorings was controlled by the plasma etching process, and the width of the Nanorings was controlled b...
Zhaoming Wang - One of the best experts on this subject based on the ideXlab platform.
-
nano petri dish array assisted glancing angle sputtering for ag np assembled bi Nanoring arrays as effective sers substrates
ACS Applied Materials & Interfaces, 2014Co-Authors: Guowen Meng, Qing Huang, Chuhong Zhu, Bensong Chen, Zhulin Huang, Zhaoming WangAbstract:Nano-petri-dish array assisted glancing angle Ag-sputtering was reported to synthesize Ag-nanoparticle (Ag-NP) assembled bi-Nanoring arrays as surface-enhanced Raman scattering (SERS) substrates. By manipulating the sputtering-Ag duration, the gaps between the Ag-NPs in the bi-Nanorings are tunable to acquire optimal electromagnetic field enhancement, and the ordered bi-Nanoring arrays ensure excellent reproducibility for Raman measurement. Such as-fabricated Ag-NPs assembled Nanoring arrays exhibit excellent SERS performance, not only 1 × 10–12 M rhodamine 6G has been identified, but also polychlorinated biphenyls with a low concentration down to 1 × 10–9 M has been recognized, showing great potential in the detection of trace organic pollutants in the environment.
-
nano petri dish array assisted glancing angle sputtering for ag np assembled bi Nanoring arrays as effective sers substrates
ACS Applied Materials & Interfaces, 2014Co-Authors: Xiaoye Hu, Guowen Meng, Qing Huang, Bensong Chen, Zhulin Huang, Fadi Li, Zhaoming WangAbstract:Nano-petri-dish array assisted glancing angle Ag-sputtering was reported to synthesize Ag-nanoparticle (Ag-NP) assembled bi-Nanoring arrays as surface-enhanced Raman scattering (SERS) substrates. By manipulating the sputtering-Ag duration, the gaps between the Ag-NPs in the bi-Nanorings are tunable to acquire optimal electromagnetic field enhancement, and the ordered bi-Nanoring arrays ensure excellent reproducibility for Raman measurement. Such as-fabricated Ag-NPs assembled Nanoring arrays exhibit excellent SERS performance, not only 1 × 10–12 M rhodamine 6G has been identified, but also polychlorinated biphenyls with a low concentration down to 1 × 10–9 M has been recognized, showing great potential in the detection of trace organic pollutants in the environment.
Guowen Meng - One of the best experts on this subject based on the ideXlab platform.
-
nano petri dish array assisted glancing angle sputtering for ag np assembled bi Nanoring arrays as effective sers substrates
ACS Applied Materials & Interfaces, 2014Co-Authors: Guowen Meng, Qing Huang, Chuhong Zhu, Bensong Chen, Zhulin Huang, Zhaoming WangAbstract:Nano-petri-dish array assisted glancing angle Ag-sputtering was reported to synthesize Ag-nanoparticle (Ag-NP) assembled bi-Nanoring arrays as surface-enhanced Raman scattering (SERS) substrates. By manipulating the sputtering-Ag duration, the gaps between the Ag-NPs in the bi-Nanorings are tunable to acquire optimal electromagnetic field enhancement, and the ordered bi-Nanoring arrays ensure excellent reproducibility for Raman measurement. Such as-fabricated Ag-NPs assembled Nanoring arrays exhibit excellent SERS performance, not only 1 × 10–12 M rhodamine 6G has been identified, but also polychlorinated biphenyls with a low concentration down to 1 × 10–9 M has been recognized, showing great potential in the detection of trace organic pollutants in the environment.
-
nano petri dish array assisted glancing angle sputtering for ag np assembled bi Nanoring arrays as effective sers substrates
ACS Applied Materials & Interfaces, 2014Co-Authors: Xiaoye Hu, Guowen Meng, Qing Huang, Bensong Chen, Zhulin Huang, Fadi Li, Zhaoming WangAbstract:Nano-petri-dish array assisted glancing angle Ag-sputtering was reported to synthesize Ag-nanoparticle (Ag-NP) assembled bi-Nanoring arrays as surface-enhanced Raman scattering (SERS) substrates. By manipulating the sputtering-Ag duration, the gaps between the Ag-NPs in the bi-Nanorings are tunable to acquire optimal electromagnetic field enhancement, and the ordered bi-Nanoring arrays ensure excellent reproducibility for Raman measurement. Such as-fabricated Ag-NPs assembled Nanoring arrays exhibit excellent SERS performance, not only 1 × 10–12 M rhodamine 6G has been identified, but also polychlorinated biphenyls with a low concentration down to 1 × 10–9 M has been recognized, showing great potential in the detection of trace organic pollutants in the environment.
Peng Zheng - One of the best experts on this subject based on the ideXlab platform.
-
tailoring optical properties of a large area plasmonic gold Nanoring array pattern
Journal of Physical Chemistry C, 2018Co-Authors: Sujan Kasani, Peng ZhengAbstract:A new fabrication route, which combines nanosphere lithography with silicon-based clean-room microfabrication processes, has been developed to produce large-area long-range ordered gold Nanoring array patterns in a controllable fashion. Both the experimentation and the finite-difference time-domain (FDTD) simulation show that the surface plasmon resonance peak (SPR) of the Nanoring array pattern can be tuned systematically in a large spectral range by varying the geometry parameters such as the ring thickness, the ring height, the ringer outer diameter, and the gap between neighboring rings. For the Au Nanoring arrays with a large gap in the absence of plasmon coupling between neighboring rings, the local electromagnetic (EM) field enhancement occurs at both the outer and inner surfaces of individual Nanorings; and the periodicity of Au Nanoring array has no any effect on the plasmonic properties. For the Au Nanoring arrays with a small gap, plasmon coupling takes place between neighboring rings. As a res...
-
tailoring optical properties of a large area plasmonic gold Nanoring array pattern
The Journal of Physical Chemistry, 2017Co-Authors: Sujan Kasani, Peng ZhengAbstract:A new fabrication route, which combines nanosphere lithography with silicon-based clean-room microfabrication processes, has been developed to produce large-area long-range ordered gold Nanoring array patterns in a controllable fashion. Both the experimentation and the finite-difference time-domain (FDTD) simulation show that the surface plasmon resonance peak (SPR) of the Nanoring array pattern can be tuned systematically in a large spectral range by varying the geometry parameters such as the ring thickness, the ring height, the ringer outer diameter, and the gap between neighboring rings. For the Au Nanoring arrays with a large gap in the absence of plasmon coupling between neighboring rings, the local electromagnetic (EM) field enhancement occurs at both the outer and inner surfaces of individual Nanorings; and the periodicity of Au Nanoring array has no any effect on the plasmonic properties. For the Au Nanoring arrays with a small gap, plasmon coupling takes place between neighboring rings. As a result, the characteristic plasmonic band is split into two new peaks corresponding to a bonding SPR mode and an antibonding SPR mode. The local EM field enhancement becomes stronger with a decrease in the gap between neighboring rings, but the SPR peaks shift away. Therefore, to maximize the surface-enhanced Raman scattering signal, the geometry parameters of the Au Nanoring array need to be tuned to balance the contributions from the resonance excitation (spectral overlap) and the local EM field enhancement.
Harry L. Anderson - One of the best experts on this subject based on the ideXlab platform.
-
A Complex Comprising a Cyanine Dye Rotaxane and a Porphyrin Nanoring as a Model Light‐Harvesting System
Angewandte Chemie (International ed. in English), 2020Co-Authors: Jiratheep Pruchyathamkorn, William J. Kendrick, Andrew T. Frawley, Andrea Mattioni, Felipe Caycedo-soler, Susana F. Huelga, Martin B. Plenio, Harry L. AndersonAbstract:A Nanoring-rotaxane supramolecular assembly with a Cy7 cyanine dye (hexamethylindotricarbocyanine) threaded along the axis of the Nanoring was synthesized as a model for the energy transfer between the light-harvesting complex LH1 and the reaction center in purple bacteria photosynthesis. The complex displays efficient energy transfer from the central cyanine dye to the surrounding zinc porphyrin Nanoring. We present a theoretical model that reproduces the absorption spectrum of the Nanoring and quantifies the excitonic coupling between the Nanoring and the central dye, thereby explaining the efficient energy transfer and demonstrating similarity with structurally related natural light-harvesting systems.
-
a complex comprising a cyanine dye rotaxane and a porphyrin Nanoring as a model light harvesting system
Angewandte Chemie, 2020Co-Authors: Jiratheep Pruchyathamkorn, William J. Kendrick, Andrew T. Frawley, Andrea Mattioni, Susana F. Huelga, Martin B. Plenio, Felipe Caycedosoler, Harry L. AndersonAbstract:A Nanoring-rotaxane supramolecular assembly with a Cy7 cyanine dye (hexamethylindotricarbocyanine) threaded along the axis of the Nanoring was synthesized as a model for the energy transfer between the light-harvesting complex LH1 and the reaction center in purple bacteria photosynthesis. The complex displays efficient energy transfer from the central cyanine dye to the surrounding zinc porphyrin Nanoring. We present a theoretical model that reproduces the absorption spectrum of the Nanoring and quantifies the excitonic coupling between the Nanoring and the central dye, thereby explaining the efficient energy transfer and demonstrating similarity with structurally related natural light-harvesting systems.
-
Tuning the Circumference of Six-Porphyrin Nanorings
2019Co-Authors: Renée Haver, Michel Rickhaus, Michael Jirásek, Lara Tejerina, Hua-wei Jiang, Laura M. Herz, Isabell Grübner, Hannah J. Eggimann, Harry L. AndersonAbstract:Most macrocycles are made from a simple repeat unit, resulting in high symmetry. Breaking this symmetry allows fine-tuning of the circumference, providing better control of the host–guest behavior and electronic structure. Here, we present the template-directed synthesis of two unsymmetrical cyclic porphyrin hexamers with both ethyne (C2) and butadiyne (C4) links, and we compare these Nanorings with the symmetrical analogues with six ethyne or six butadiyne links. Inserting two extra carbon atoms into the smaller Nanoring causes a spectacular change in binding behavior: the template affinity increases by a factor of 3 × 109, to a value of ca. 1038 M–1, and the mean effective molarity is ca. 830 M. In contrast, removing two carbon atoms from the largest Nanoring results in almost no change in its template-affinity. The strain in these Nanorings is 90–130 kJ mol–1, as estimated both from DFT calculation of homodesmotic reactions and from comparing template affinities of linear and cyclic oligomers. Breaking the symmetry has little effect on the absorption and fluorescence behavior of the Nanorings: the low radiative rates that are characteristic of a circular delocalized S1 excited state are preserved in the low-symmetry macrocycles
-
Unexpected Interactions between Alkyl Straps and Pyridine Ligands in Sulfur-Strapped Porphyrin Nanorings
2017Co-Authors: Cécile Roche, Amber L Thompson, Hua-wei Jiang, Qianfu Luo, Guzmán Gil-ramírez, Daniel R. Kohn, Yaoyao Xiong, Harry L. AndersonAbstract:Strapped or “basket-handle” porphyrins have been investigated previously as hemoglobin mimics and catalysts. The facial selectivity of their interactions with axial ligands is a sensitive test for noncovalent bonding. Here the binding of pyridyl ligands to zinc porphyrins with thioester-linked alkyl straps is investigated in solution by NMR spectroscopy and UV–vis titration, and in the solid state by X-ray crystallography. We expected that coordination of the axial ligand would occur on the less hindered face of the porphyrin, away from the strap. Surprisingly, attractive interactions between the strap and the ligand direct axial coordination to the strapped face of the porphyrin, except when the strap is short and tight. The strapped porphyrins were incorporated into π-conjugated cyclic porphyrin hexamers using template-directed synthesis. The strap and the sulfur substituents are located either inside or outside the porphyrin Nanoring, depending on the length of the strap. Six-porphyrin Nanorings with outwardly pointing sulfur anchors were prepared for exploring quantum interference effects in single-molecule charge transport
-
Size-Independent Energy Transfer in Biomimetic Nanoring Complexes
ACS nano, 2016Co-Authors: Patrick Parkinson, Harry L. Anderson, Nuntaporn Kamonsutthipaijit, Laura M. HerzAbstract:Supramolecular antenna-ring complexes are of great interest due to their presence in natural light-harvesting complexes. While such systems are known to provide benefits through robust and efficient energy funneling, the relationship between molecular structure, strain (governed by nuclear coordinates and motion), and energy dynamics (arising from electronic behavior) is highly complex. We present a synthetic antenna-Nanoring system based on a series of conjugated porphyrin chromophores ideally suited to explore such effects. By systematically varying the size of the acceptor Nanoring, we reveal the interplay between antenna-Nanoring binding, local strain, and energy dynamics on the picosecond time scale. Binding of the antenna unit creates a local strain in the Nanoring, and this strain was measured as a function of the size of the Nanoring, by UV–vis-NIR titration, providing information on the conformational flexibility of the system. Strikingly, the energy-transfer rate is independent of Nanoring size,...
