A5074645467- Graphene research and applications
- Carbon Nanotubes in Composites
- 2D Materials and Applications
- Chalcogenide Semiconductor Thin Films
- Molecular Spectroscopy and Structure
- Gold and Silver Nanoparticles Synthesis and Applications
- Spectroscopy Techniques in Biomedical and Chemical Research
- Diamond and Carbon-based Materials Research
- Quantum and electron transport phenomena
- Molecular Junctions and Nanostructures
- Nanopore and Nanochannel Transport Studies
- Spectroscopy and Laser Applications
- Advanced Chemical Physics Studies
- Mechanical and Optical Resonators
- Organic and Molecular Conductors Research
- Electrochemical Analysis and Applications
- Quantum Dots Synthesis And Properties
- Semiconductor materials and devices
- Perovskite Materials and Applications
- Force Microscopy Techniques and Applications
- Machine Learning in Materials Science
- Solid-state spectroscopy and crystallography
- Fullerene Chemistry and Applications
- Graphene and Nanomaterials Applications
- Characterization and Applications of Magnetic Nanoparticles
Physical Measurement Laboratory
2016-2025
National Institute of Standards and Technology
2016-2025
Quantum (Australia)
2025
Material Measurement Laboratory
2022-2024
National Institute of Standards
2006-2023
Macalester College
2023
Center for Nanoscale Science and Technology
2022
United States Naval Research Laboratory
2022
Nova Research Company (United States)
2022
Theiss Research
2022
We present the results of a thorough study wet chemical methods for transferring vapor deposition grown graphene from metal growth substrate to device-compatible substrate. On basis these results, we have developed "modified RCA clean" transfer method that has much better control both contamination and crack formation does not degrade quality transferred graphene. Using this method, high device yields, up 97%, with narrow performance metrics distribution were achieved. This demonstration...
Atomically thin molybdenum disulfide (MoS2) offers potential for advanced devices and an alternative to graphene due its unique electronic optical properties. The temperature-dependent Raman spectra of exfoliated, monolayer MoS2 in the range 100-320 K are reported analyzed. linear temperature coefficients in-plane E2g 1 out-of-plane A1g modes both suspended substrate-supported measured. These data, when combined with first-order from laser power-dependent studies, enable thermal conductivity...
Abstract Anisotropic metallic nanoparticles (NPs) have unique optical properties, which lend them to applications such as surface‐enhanced Raman scattering (SERS) spectroscopy. Star‐shaped gold (Au) NPs were prepared in aqueous solutions by the seed‐mediated growth method and tested for enhancement using 2‐mercaptopyridine (2‐MPy) crystal violet (CV) probing molecules. For both molecules, SERS activity of nanostars was notably stronger than that spherical Au similar size. The factors (EFs)...
Aqueous two-phase extraction is demonstrated to enable isolation of single semiconducting and metallic single-wall carbon nanotube species from a synthetic mixture. The separation rapid robust, with remarkable tunability via modification the surfactant environment set for separation.
Ultrasensitive and quantitative detection of cancer biomarkers is an unmet challenge because their ultralow concentrations in clinical samples. Although gold nanoparticle (AuNP)-based immunoassays offer high sensitivity, they were unable to quantitatively detect targets interest most likely due very narrow linear ranges. This article describes a colorimetric immunoassay based on glucose oxidase (GOx)-catalyzed growth 5 nm AuNPs that can from attomolar picomolar levels. In addition, the limit...
It is still in high demand to develop extremely sensitive and accurate clinical tools for biomarkers of interest early diagnosis monitoring diseases. In this report, we present a highly compatible gold nanoparticle (AuNP)-based fluorescence-activatable probe sensing ultralow levels prostate-specific antigen (PSA) patient serum samples. The limit detection the newly developed PSA was pushed down 0.032 pg/mL, which more than 2 orders magnitude lower that conventional fluorescence probe....
In this contribution we demonstrate the effective separation of single-wall carbon nanotube (SWCNT) species with diameters larger than 1 nm through multistage aqueous two-phase extraction (ATPE), including isolation at near-monochiral level up to least diameter range SWCNTs synthesized by electric arc synthesis (1.3-1.6 nm). We also that refined are readily obtained from both metallic and semiconducting subpopulations methodology is for multiple SWCNT raw materials. Using these data, report...
Metal organic framework-5 (MOF-5) was recently suggested to possess an exceptionally large negative thermal-expansion coefficient. Our direct experimental measurement of the thermal expansion MOF-5 using neutron powder diffraction, in temperature range 4 600 K, shows that linear coefficient is $\ensuremath{\approx}\ensuremath{-}16\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}\text{ }{\text{K}}^{\ensuremath{-}1}$. To understand origin this behavior, we performed first-principles...
This paper reports an interlaboratory comparison that evaluated a protocol for measuring and analysing the particle size distribution of discrete, metallic, spheroidal nanoparticles using transmission electron microscopy (TEM). The study was focused on automated image capture analysis. NIST RM8012 gold (30 nm nominal diameter) were measured area-equivalent diameter distributions by eight laboratories. Statistical analysis used to (1) assess data quality without reference models, (2)...
We report reduced contact resistance of single-layer graphene devices by using ultraviolet ozone (UVO) treatment to modify the metal/graphene interface. The were fabricated from mechanically transferred, chemical vapor deposition (CVD) grown, single layer graphene. UVO in regions as defined photolithography and prior metal was found reduce interface contamination originating incomplete removal poly(methyl methacrylate) (PMMA) photoresist. Our control experiment shows that exposure times up...
Developing processes to controllably dope transition-metal dichalcogenides (TMDs) is critical for optical and electrical applications. Here, molecular reductants oxidants are introduced onto monolayer TMDs, specifically MoS
Seeing is believing: A rapid diagnostic platform for pathogen detection based on the acetylcholinesterase-catalyzed hydrolysis reaction has been developed. Owing to signal amplification strategies, sensitivity of this assay comparable that PCR. In addition, readout solution color change, which can be easily observed by naked eye alone. As a service our authors and readers, journal provides supporting information supplied authors. Such materials are peer reviewed may re-organized online...
In ReS$_2$ a layer-independent direct band-gap of 1.5 eV implies potential for its use in optoelectronic applications. crystallizes the 1T$^{\prime}$-structure which leads to anisotropic physical properties and whose concomitant electronic structure might host non-trivial topology. Here, we report an overall evaluation Raman response transport few-layered field-effect transistors. We find that exfoliated on SiO$_2$ behaves as $n$-type semiconductor with intrinsic carrier mobility surpassing...
In this work, we compare the electrical characteristics of MoS2 field-effect transistors (FETs) with Ag source/drain contacts those Ti and demonstrate that metal–MoS2 interface is crucial to device performance. FETs show more than 60 times higher ON-state current contacts. order better understand mechanism performance contacts, 5 nm Au/5 (contact layer) or film was deposited onto monolayers few layers, topography metal films characterized using scanning electron microscopy atomic force...
This work expands the redox chemistry of single-wall carbon nanotubes (SWCNTs) by investigating its role in a number SWCNT sorting processes. Using polyethylene glycol (PEG)/dextran (DX) aqueous two-phase system, we show that electron-transfer between molecules and SWCNTs triggers reorganization surfactant coating layer, leading to strong modulation nanotube partition two phases. While DX phase is thermodynamically more favored an oxidized mixture, mildly reducing PEG able recover from...
Recently it was discovered that van der Waals bonded magnetic materials retain long range ordering down to a single layer, opening many avenues in fundamental physics and potential applications of these fascinating materials. One such material is $\mathrm{FeP}{\mathrm{S}}_{3}$, large spin $(S=2)$ Mott insulator where the Fe atoms form honeycomb lattice. In bulk, $\mathrm{FeP}{\mathrm{S}}_{3}$ has been shown be quasi-two-dimensional-Ising antiferromagnet, with additional features Raman...
The discovery of 2-dimensional (2D) materials, such as CrI3, that retain magnetic ordering at monolayer thickness has resulted in a surge both pure and applied research 2D magnetism. Here, we report magneto-Raman spectroscopy study on multilayered focusing two additional features the spectra appear below temperature were previously assigned to high frequency magnons. Instead, conclude these modes are actually zone-folded phonons. We observe striking evolution Raman with increasing field...
Strong hybridization of two-magnon scattering with phonons is observed in 2D antiferromagnet MnPSe 3 .
Covalent modification of carbon nanotubes is a promising strategy for engineering their electronic structures. However, keeping sites in registration with nanotube lattice challenging. We report solution using DNA-directed, guanine (G)-specific cross-linking chemistry. Through DNA screening we identify sequence, C3GC7GC3, whose reaction an (8,3) enantiomer yields minimum disorder-induced Raman mode intensities and photoluminescence Stokes shift, suggesting ordered defect array formation....
Separating oxygen from air to create oxygen-enriched gas streams is a process that significant in both industrial and medical fields. However, the prominent technologies for creating are energy infrastructure intensive as they use cryogenic temperatures or materials adsorb N2 air. The latter method less efficient than methods O2 directly. Herein, we show, via combination of adsorption isotherms, breakthrough experiments, neutron synchrotron X-ray powder diffraction, Raman spectroscopy,...
Among the novel chemical and physical attributes of single-wall carbon nanotubes (SWCNTs), optical properties are perhaps most compelling. Although much is known about how such characteristics depend on nanotube chirality diameter, relatively little response depends length, next obvious fundamental trait. We show here that intrinsic exhibits a strong dependence we offer simple explanation relates this behavior to localization bound exciton along length nanotube. The results presented suggest...
Under the influence of a 0.05 T magnetic field, 15-nm diameter cobalt nanoparticles covered with surfactants in colloidal solution assemble into highly constrained linear chains along direction field. The magnetic-field-induced (MFI) become floppy after removal folding three-dimensional (3D) coiled structures upon gentle agitation. 3D are broken smaller units vigorous redisperse solvent ultrasonic Optical microscopy and transmission electron (TEM) used to characterize morphologies...