A5043667856- Molecular Junctions and Nanostructures
- Semiconductor materials and devices
- Spectroscopy and Laser Applications
- Nanowire Synthesis and Applications
- Silicon Nanostructures and Photoluminescence
- Water Quality Monitoring and Analysis
- Semiconductor Quantum Structures and Devices
- Analytical Chemistry and Sensors
- Advanced Semiconductor Detectors and Materials
- Force Microscopy Techniques and Applications
- Quantum Dots Synthesis And Properties
- Spectroscopy and Quantum Chemical Studies
- Semiconductor materials and interfaces
- Near-Field Optical Microscopy
- Metal-Organic Frameworks: Synthesis and Applications
- Chalcogenide Semiconductor Thin Films
- Photoacoustic and Ultrasonic Imaging
- Advancements in Battery Materials
- Photochemistry and Electron Transfer Studies
- Organic Electronics and Photovoltaics
- Ion-surface interactions and analysis
- Electrochemical Analysis and Applications
- Water Quality Monitoring Technologies
- Supercapacitor Materials and Fabrication
- Electron and X-Ray Spectroscopy Techniques
The University of Texas at Dallas
2009-2020
IntelliEPI (United States)
2016-2018
Leibniz Institute for Analytical Sciences - ISAS
2010
Sorbonne Université
2010
Centre National de la Recherche Scientifique
2010
Helmholtz-Zentrum Berlin für Materialien und Energie
2009
Hasselt University
2008
Deutsches Elektronen-Synchrotron DESY
2007
Technical University of Darmstadt
2007
Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute
2005
Abstract Vanadium pentoxide (V 2 O 5 ) layered nanostructures are known to have very stable crystal structures and high faradaic activity. The low electronic conductivity of V greatly limits the application vanadium oxide as electrode materials requires combining with conducting using binders. It is well that organic binders can degrade overall performance need carefully controlled compositions. In this study, we develop a simple method for preparing freestanding carbon nanotube (CNT)‐V...
Water cluster formation and methane adsorption within a hydrophobic porous metal organic framework is studied by in situ vibrational spectroscopy, isotherms, first-principle DFT calculations (using vdW-DF). Specifically, the stability of H2O clusters cavities fluorinated metal–organic (FMOF-1) examined. Although isotherms water show no measurable uptake (see Yang et al. J. Am. Chem. Soc. 2011, 133, 18094), large dipole internal modes makes it possible to detect low concentrations using IR...
The unusual uptake behavior and preferential adsorption of CO(2) over N(2) are investigated in a flexible metal-organic framework system, Zn(2)(bdc)(2)(bpee), where bpdc = 4,4'-biphenyl dicarboxylate bpee 1,2-bis(4-pyridyl)ethylene, using Raman IR spectroscopy. results indicate that the interaction with induces twisting one its ligands, which is possible because type connectivity carboxylate end group ligand to metal center specific framework. flexibility pillars allows structure respond...
Silicon anodes based on an alloy reaction with lithium have a large theoretical specific capacity making them appealing candidate for use in lithium-ion batteries. A major factor influencing the power cyclability and cycle life of battery is formation solid electrolyte interphase (SEI) layer. In this work, progression SEI hydrogenated amorphous Si (a-Si:H) determined as function applied electrochemical potential during first charging by combining cyclic voltammetry measurements detailed...
The irradiation-induced reduction of electrochemically grafted nitrobenzene films on Si(111) was monitored by high-resolution photoelectron spectroscopy. experiments were performed using synchrotron soft X-ray irradiation at the BESSY II facility. evolution different chemical species as a function time. Careful fitting Si2p, C1s, N1s, and O1s core level spectra allowed us to follow this process in detail determine constants growth decay specific components. changes caused secondary electron...
The use of nanoparticles for advanced applications critically depends on the control interfaces between substrate, intermediate/linking layer, and nanostructures. While much work has been done to attach determine their properties, less effort devoted quality starting surfaces little is known about impact attachment process pre-existing interfaces. In this study, properties two model obtained by covalently grafting alkyl chains directly oxide-free silicon surfaces, either via Si−O−C or Si−C...
This work describes further development of the confinement theory used for fitting Raman-spectroscopy signal obtained from nanostructured materials. We present a simple algebraic method incorporation an anisotropic phonon-dispersion function into phonon model. The anisotropy is shown to have particular effects on low-dimensional systems, sizes below $\ensuremath{\sim}15\text{ }\text{nm}$, even systems with low such as Ge. Experimental verification model provided by Raman Ge nanowires grown...
Freezing out of molecular motion and increased tilt enhance the efficiency electron transport through alkyl chain monolayers that are directly chemically bound to oxide-free Si. As a result, current across such increases as temperature decreases from room ∼80 K, i.e., opposite thermally activated hopping or semiconductor transport. The 30-fold change for an 18-carbon long monolayer is several times resistance actual metals over this range. FTIR vibrational spectroscopic measurements indicate...
XeF2 treatment of aluminum and alumina surfaces is known to produce hydrophilic surfaces. There however poor knowledge the chemical nature these Using infrared absorption X-ray photoelectron spectroscopy, formation highly AlF3 AlOxFy surface layers identified upon exposure, along with strongly bound H2O other related species formed by interactions trace under typical vacuum conditions (≈10–4 Torr). Surfaces resulting from etching oxide-free covered a sacrificial Si layer have strong affinity...
Label-free detection of DNA molecules on chemically vapor-deposited diamond surfaces is achieved with spectroscopic ellipsometry in the infrared and vacuum ultraviolet range. This nondestructive method has potential to yield information average orientation single as well double-stranded molecules, without restricting strand length persistence length. The orientational analysis based electronic excitations combination from layer thicknesses provides a deeper understanding biological layers...
The electrochemical grafting process of 4-nitrobenzene and 4-methoxybenzene (anisole) from diazonium salt solutions has been investigated in situ by monitoring the current density, band bending, nonradiative surface recombination during at different potentials concentrations solution. Ex infrared spectroscopic ellipsometry used to inspect Si species before after process. bending decreases with either increasing concentration or when redox potential compound is nearer competing H+/H2 couple....
An infrared microfocus spectroscopic mapping ellipsometer was set up at the Berlin electron synchrotron storage ring and used to study ultrathin polyacrylic acid brush films with 3nm thickness. The pH-responsive properties of on a gold-coated glass substrate were investigated. chemical structure resolved spatial resolution 300μm using ellipsometer.
Covalent grafting of ethynyl derivatives (-C triple bond C-H, -C C-CH3, C-aryl) onto H-terminated Si(111) surfaces was performed by a one-step anodic treatment in Grignard electrolytes. The electrochemical such derivatives, which tends to form ultrathin polymeric layers, can be controlled the current and charge flow passing through Si electrode. prepared layers cover surface had thickness up 20 nm, as investigated scanning electron microscopy (SEM) technique. Exchanging Cl for Br reagent...
We report on developments in scanning near-field infrared microscopy where the elements are silver–halide tapered fiber probes. These probes showed good transmission efficiency and a transparency over very wide spectral range (0.6–10 μm), which may prove useful high-resolution spectroscopy. performed spatial characterization of radiation distribution emitted from these probes, using knife-edge technique. The obtained profiles, measured both for midinfrared visible radiation, were consistent...
This paper aims to demonstrate the high capability of infrared spectroscopic ellipsometry (IRSE) for characterization very thin organic films and inorganic interfaces. It is shown that detection limit IRSE facilitates investigation ultrathin nitrobenzene (NB) with monolayer sensitivity. accounts substrates from semiconductors metals. The process reoxidation a NB terminated silicon (001) surface also reflected in ellipsometric parameters evidently proceeds despite layer. As complementary...
Control over the Te doping concentration is especially challenging in mass-production of optically transparent, high-resistivity Te-doped GaSb crystals. Driven by necessity to perform fast, robust, and non-destructive quality control homogeneity transparent large-diameter wafers, we correlated electronic optical infrared properties The study was based on experimental Hall Fourier-Transform Infrared (FTIR) data collected from 50 samples low-doped n-type material (carrier 6 × 1016 cm−3 7 1017...
Infrared spectroscopic ellipsometry (IRSE) was applied for characterization of porous silicon (PSi) electrochemically prepared in acidic fluoride solution. When no formation SiO2 involved the preparation, an anisotropic distribution PSi bonds with terminating molecules achieved. On contrary, oxidation samples during preparation led to isotropic structure. IR spectra obtained from organically functionalized surfaces suggested that morphology organic layer on electrochemical grafting methyl...
Optical properties of thin films aggregated thiacarbocyanine (TCC) dyes have been studied by means spectroscopic ellipsometry and polarized IR spectroscopy. The experimental results reveal a strongly anisotropic response the films, as quantified in reported dielectric functions over wide range frequencies. TCC exhibit both J-aggregate H-aggregate absorption bands with different polarization properties. A strong resonance arising from electronic excitations was found to be along film....
Here the microscopic mechanism that leads to surprising formation of a nanopattern upon methanol reacting with H-terminated Si(111) surface [Michalak et al., Nat. Mater. 2010, 9, 266–271] is reinvestigated from both theory and experiment. First-principles calculations determine fully OCH3-terminated as thermodynamic ground state in presence methanol, seemingly contrast experimentally found nanopattern. At 65 °C H2 initiates desorption methoxy groups thereby dynamic equilibrium reaction...
Removal of Si sacrificial layer from Al surfaces using XeF2 gas results in highly adhesive aluminum (oxy)fluoride surfaces. We describe the preparation and characterization improved, nonstick modified with octadecyltrichlorosilane (OTS). High hydrophilicity AlFx is key factor for attachment OTS, where Al−F surface bond hydrolyzed to form Al−O−Si link OTS. Infrared absorption data indicate that a dense Si−O−Si network formed above upon Based on optical modeling ν(CH2) bands, an average tilt...