The Experts below are selected from a list of 64317 Experts worldwide ranked by ideXlab platform
Masatoshi Osawa - One of the best experts on this subject based on the ideXlab platform.
-
potential induced restructuring dynamics of ionic liquids on a gold electrode steric effect of constituent ions studied by surface enhanced Infrared Absorption Spectroscopy
2017Co-Authors: Kenta Motobayashi, Kazuya Minami, Naoya Nishi, Tetsuo Sakka, Yuki Inoue, Masatoshi OsawaAbstract:Abstract The structure of the interface between room temperature ionic liquids (RTILs) and an Au electrode changes with applied potential to compensate the charge on the electrode surface. The dynamics of the restructuring of RTILs triggered by the change in potential has been investigated by using surface-enhanced Infrared Absorption Spectroscopy (SEIRAS). To elucidate the effect of steric hindrance of constituent ions on the potential-dependent dynamics, RTILs composed of differently sized ions are examined: imidazolium cations and bis(perfluoroalkylsulfonyl)amide anions with different (perfluoro)alkyl chain length, or tetrafluoroborate anion. The high interface selectivity and sensitivity of SEIRAS enables in-situ, real time observation of dynamic behaviors of both anions and cations during potential scans or steps. During potential scans for RTILs composed of sufficiently large ions (all the RTILs examined in the present study except for that includes BF 4 − ), a fast, barrier-less change in local ion concentration occurs in the overlayers first, and then a slow cation-anion replacement occurs in the first ionic layer directly contacting with the electrode surface when an overpotential exceeding a critical value is applied. SEIRAS reveals hysteretic changes of the interfacial structure arising from the ion replacement in the first ionic layer. Potential-dependent SEIRAS measurements for RTILs with different ion sizes highlight the significance of steric hindrance of ions for the ion replacement in the first layer.
-
potential dependent condensation of water at the interface between ionic liquid bmim tfsa and an au electrode
2016Co-Authors: Kenta Motobayashi, Masatoshi OsawaAbstract:Abstract Surface-enhanced Infrared Absorption Spectroscopy (SEIRAS) at the interface between humid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([BMIM][TFSA]) and an Au electrode reveals that water molecules strongly interact with the anion and are condensed at the interface at high potentials where the anion is the major adsorbate.
-
hysteresis of potential dependent changes in ion density and structure of an ionic liquid on a gold electrode in situ observation by surface enhanced Infrared Absorption Spectroscopy
2013Co-Authors: Kenta Motobayashi, Kazuya Minami, Naoya Nishi, Tetsuo Sakka, Masatoshi OsawaAbstract:Potential-dependent structure and dynamics of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([BMIM][TFSA]) on an Au electrode have been investigated by using surface-enhanced Infrared Absorption Spectroscopy (SEIRAS). In situ, real-time IR measurements during potential scans enable us to probe a hysteretic exchange and reorientation of both the cation and anion at the interface simultaneously owing to the high interface selectivity and sensitivity of SEIRAS. Our experimental results reveal that during potential scans, the ion density in overlayers changes first, and then the exchange of the ions in the first ionic layer occurs to compensate the changes in surface charge.
-
formic acid electrooxidation on pd in acidic solutions studied by surface enhanced Infrared Absorption Spectroscopy
2008Co-Authors: Hiroto Miyake, Gabor Samjeske, Tatsuhiro Okada, Masatoshi OsawaAbstract:A mechanistic study of electrocatalytic oxidation of formic acid on Pd in sulfuric and perchloric acids is reported. Surface-enhanced Infrared Absorption Spectroscopy in the attenuated total reflection mode (ATR-SEIRAS) shows the adsorption of CO, bridge-bonded formate, bicarbonate, and supporting anions on the electrode surface. Poisoning of the Pd surface by CO, formed by dehydration of formic acid, is very slow and scarcely affects formic acid oxidation. The anions are adsorbed more strongly in the order of (bi)sulfate > bicarbonate > perchlorate, among which the most strongly adsorbed (bi)sulfate considerably suppresses formic acid oxidation in the double layer region. The oxidation is suppressed also at higher potentials in both acids by the oxidation of the Pd surface. Adsorbed formate is detected only when formic acid oxidation is suppressed. The results show that formate is a short-lived reactive intermediate in formic acid oxidation and is hence detected when its decomposition yielding CO2 is suppressed. The high electrocatalytic activity of Pd can be ascribed to the high tolerance to CO contamination and also high catalytic activity toward formate decomposition.
-
structure of water at the electrified platinum water interface a study by surface enhanced Infrared Absorption Spectroscopy
2008Co-Authors: Masatoshi Osawa, Minoru Tsushima, Hirokazu Mogami, Gabor Samjeske And, Akira YamakataAbstract:Surface-enhanced Infrared Absorption Spectroscopy in the attenuated total reflection mode is used to examine the structure of water on a polycrystalline Pt electrode in H2SO4 and HClO4 as a function of applied potential. The electrode surface covered with CO is used as the reference in recording spectra, which enables us to obtain the absolute Infrared spectrum of the interfacial water layer (monolayer or bilayer) in contact with the surface with negligible interference from the bulk water. The spectrum of the interfacial water is largely different from that of bulk water and changes around the potential of zero charge of the electrode. The spectral changes are ascribed to the potential-dependent reorientation of water molecules from a weakly hydrogen-bonded oxygen-up orientation at the negatively charged surface to a strongly hydrogen-bonded nearly flat orientation at the positively charged surface in agreement with theoretical simulations reported in the literature. Clear experimental evidence of the fo...
Hatice Altug - One of the best experts on this subject based on the ideXlab platform.
-
engineering mid Infrared nanoantennas for surface enhanced Infrared Absorption Spectroscopy
2015Co-Authors: Ronen Adato, Serap Aksu, Hatice AltugAbstract:Mid-Infrared Absorption Spectroscopy is a powerful tool for optically probing the molecular structure of biological samples. However, using conventional approaches, IR measurements on small quantities of molecules are extremely challenging due to sensitivity limitations. The strong IR Absorption of liquid water presents additional obstacles to performing measurements in biomolecules’ native, aqueous environments. In this review we discuss the application of engineered plasmonic nanoantennas to overcoming these challenges. We provide overviews and highlight the key concepts of our recent work in designing Infrared antennas and applying them to enhance the Absorption of minute quantities of biomolecules as well as new fabrication methods for their high throughput and low-cost manufacturing.
-
in situ ultra sensitive Infrared Absorption Spectroscopy of biomolecule interactions in real time with plasmonic nanoantennas
2013Co-Authors: Ronen Adato, Hatice AltugAbstract:Infrared Absorption Spectroscopy is a powerful biochemical analysis tool as it extracts detailed molecular structural information in a label-free fashion. Its molecular specificity renders the technique sensitive to the subtle conformational changes exhibited by proteins in response to a variety of stimuli. Yet, sensitivity limitations and the extremely strong Absorption bands of liquid water severely limit Infrared Spectroscopy in performing kinetic measurements in biomolecules' native, aqueous environments. Here we demonstrate a plasmonic chip-based technology that overcomes these challenges, enabling the in-situ monitoring of protein and nanoparticle interactions at high sensitivity in real time, even allowing the observation of minute volumes of water displacement during binding events. Our approach leverages the plasmonic enhancement of Absorption bands in conjunction with a non-classical form of internal reflection. These features not only expand the reach of Infrared Spectroscopy to a new class of biological interactions but also additionally enable a unique chip-based technology.
-
integrated plasmonic nanobiosensors
2013Co-Authors: Hatice Altug, Ronen Adato, Serap Aksu, Alp A Artar, Kai ChenAbstract:We will demonstrate plasmonic and metamaterial based integrated nano-biosensors and ultrasensitive Infrared Absorption Spectroscopy. These systems by enabling monitoring of molecular-protein interactions in real-time within aqueous solutions can be important for biomedical sciences and pharmacology.
A Castro H Neto - One of the best experts on this subject based on the ideXlab platform.
-
tunable optical properties of multilayer black phosphorus thin films
2014Co-Authors: A S Rodin, Yongjin Jiang, Han Wang, A Castro H Neto, A CarvalhoAbstract:Black phosphorus thin films might offer attractive alternatives to narrow gap compound semiconductors for optoelectronics across mid- to near-Infrared frequencies. In this work, we calculate the optical conductivity tensor of multilayer black phosphorus thin films using the Kubo formula within an effective low-energy Hamiltonian. The optical Absorption spectra of multilayer black phosphorus are shown to vary sensitively with thickness, doping, and light polarization. In conjunction with experimental spectra obtained from Infrared Absorption Spectroscopy, we also discuss the role of interband coupling and disorder on the observed anisotropic Absorption spectra.
-
tunable optical properties of multilayers black phosphorus
2014Co-Authors: Tony Low, A S Rodin, A F Carvalho, Yongjin Jiang, Han Wang, Fengnian Xia, A Castro H NetoAbstract:Black phosphorus thin films might offer attractive alternatives to narrow gap compound semiconductors for optoelectronics across mid- to near-Infrared frequencies. In this work, we calculate the optical conductivity tensor of multilayer black phosphorus thin films using the Kubo formula within an effective low-energy Hamiltonian. The optical Absorption spectra of multilayer black phosphorus are shown to vary sensitively with thickness, doping, and light polarization. In conjunction with experimental spectra obtained from Infrared Absorption Spectroscopy, we also discuss the role of interband coupling and disorder on the observed anisotropic Absorption spectra.
Christof Woll - One of the best experts on this subject based on the ideXlab platform.
-
photocatalytic activity of bulk tio 2 anatase and rutile single crystals using Infrared Absorption Spectroscopy
2011Co-Authors: Youkun Gao, Elias Martinez Moreno, M Kunst, Martin Muhler, Yuemin Wang, Hicham Idriss, Christof WollAbstract:A systematic study on the photocatalytic activity of well-defined, macroscopic bulk single-crystal TiO{sub 2} anatase and rutile samples has been carried out, which allows us to link photoreactions at surfaces of well-defined oxide semiconductors to an important bulk property with regard to photochemistry, the life time of e-h pairs generated in the bulk of the oxides by photon Absorption. The anatase (101) surface shows a substantially higher activity, by an order of magnitude, for CO photo-oxidation to CO{sub 2} than the rutile (110) surface. This surprisingly large difference in activity tracks the bulk e-h pair lifetime difference for the two TiO{sub 2} modifications as determined by contactless transient photoconductance measurements on the corresponding bulk materials.
-
photocatalytic activity of bulk tio 2 anatase and rutile single crystals using Infrared Absorption Spectroscopy
2011Co-Authors: Youkun Gao, Elias Martinez Moreno, M Kunst, Martin Muhler, Yuemin Wang, Hicham Idriss, Christof WollAbstract:A systematic study on the photocatalytic activity of well-defined, macroscopic bulk single-crystal ${\mathrm{TiO}}_{2}$ anatase and rutile samples has been carried out, which allows us to link photoreactions at surfaces of well-defined oxide semiconductors to an important bulk property with regard to photochemistry, the life time of $e\mathrm{\text{\ensuremath{-}}}h$ pairs generated in the bulk of the oxides by photon Absorption. The anatase (101) surface shows a substantially higher activity, by an order of magnitude, for CO photo-oxidation to ${\mathrm{CO}}_{2}$ than the rutile (110) surface. This surprisingly large difference in activity tracks the bulk $e\mathrm{\text{\ensuremath{-}}}h$ pair lifetime difference for the two ${\mathrm{TiO}}_{2}$ modifications as determined by contactless transient photoconductance measurements on the corresponding bulk materials.
Ronen Adato - One of the best experts on this subject based on the ideXlab platform.
-
engineering mid Infrared nanoantennas for surface enhanced Infrared Absorption Spectroscopy
2015Co-Authors: Ronen Adato, Serap Aksu, Hatice AltugAbstract:Mid-Infrared Absorption Spectroscopy is a powerful tool for optically probing the molecular structure of biological samples. However, using conventional approaches, IR measurements on small quantities of molecules are extremely challenging due to sensitivity limitations. The strong IR Absorption of liquid water presents additional obstacles to performing measurements in biomolecules’ native, aqueous environments. In this review we discuss the application of engineered plasmonic nanoantennas to overcoming these challenges. We provide overviews and highlight the key concepts of our recent work in designing Infrared antennas and applying them to enhance the Absorption of minute quantities of biomolecules as well as new fabrication methods for their high throughput and low-cost manufacturing.
-
in situ ultra sensitive Infrared Absorption Spectroscopy of biomolecule interactions in real time with plasmonic nanoantennas
2013Co-Authors: Ronen Adato, Hatice AltugAbstract:Infrared Absorption Spectroscopy is a powerful biochemical analysis tool as it extracts detailed molecular structural information in a label-free fashion. Its molecular specificity renders the technique sensitive to the subtle conformational changes exhibited by proteins in response to a variety of stimuli. Yet, sensitivity limitations and the extremely strong Absorption bands of liquid water severely limit Infrared Spectroscopy in performing kinetic measurements in biomolecules' native, aqueous environments. Here we demonstrate a plasmonic chip-based technology that overcomes these challenges, enabling the in-situ monitoring of protein and nanoparticle interactions at high sensitivity in real time, even allowing the observation of minute volumes of water displacement during binding events. Our approach leverages the plasmonic enhancement of Absorption bands in conjunction with a non-classical form of internal reflection. These features not only expand the reach of Infrared Spectroscopy to a new class of biological interactions but also additionally enable a unique chip-based technology.
-
integrated plasmonic nanobiosensors
2013Co-Authors: Hatice Altug, Ronen Adato, Serap Aksu, Alp A Artar, Kai ChenAbstract:We will demonstrate plasmonic and metamaterial based integrated nano-biosensors and ultrasensitive Infrared Absorption Spectroscopy. These systems by enabling monitoring of molecular-protein interactions in real-time within aqueous solutions can be important for biomedical sciences and pharmacology.