A5002698125- Ion-surface interactions and analysis
- Diamond and Carbon-based Materials Research
- Analytical chemistry methods development
- Integrated Circuits and Semiconductor Failure Analysis
- Mass Spectrometry Techniques and Applications
- Magnetic and transport properties of perovskites and related materials
- Forensic Fingerprint Detection Methods
- Electrochemical Analysis and Applications
- Electronic and Structural Properties of Oxides
- Olfactory and Sensory Function Studies
- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Digital and Cyber Forensics
- Advanced Chemical Sensor Technologies
- Nuclear Physics and Applications
- Forensic and Genetic Research
- 3D Printing in Biomedical Research
- Semiconductor materials and devices
- Advanced Condensed Matter Physics
- Additive Manufacturing and 3D Printing Technologies
- ZnO doping and properties
- Korean Peninsula Historical and Political Studies
- Gold and Silver Nanoparticles Synthesis and Applications
- Cultural Heritage Materials Analysis
- Magnetic properties of thin films
Material Measurement Laboratory
2015-2024
National Institute of Standards and Technology
2015-2024
NIST Center for Neutron Research
2022
Interface (United Kingdom)
2020-2021
University of East Asia
2020-2021
John Wiley & Sons (United States)
2020-2021
John Wiley & Sons (United Kingdom)
2021
United States Department of Commerce
2015
University of Washington
2010-2013
Yokogawa Electric (Japan)
1995
We report bandlike transport in solution-deposited, CdSe QD thin-films with room temperature field-effect mobilities for electrons of 27 cm(2)/(V s). A concomitant shift and broadening the solid optical absorption compared to that dispersed samples is consistent electron delocalization measured mobilities. Annealing indium contacts allows thermal diffusion doping thin-films, shifting Fermi energy, filling traps, providing access bands. Temperature-dependent measurements show 220 K on a...
We report a simple, solution-based, postsynthetic colloidal, atomic layer deposition (PS-cALD) process to engineer stepwise the surface stoichiometry and therefore electronic properties of lead chalcogenide nanocrystal (NC) thin films integrated in devices. found that unlike chalcogen-enriched NC surfaces are structurally, optically, electronically unstable, chloride treatment creates well-passivated shell stabilizes NCs. Using PS-cALD we demonstrate high electron field-effect mobilities...
In this study, a non-native chemical species, bromodeoxyuridine (BrdU), was imaged within single HeLa cells using time-of-flight secondary ion mass spectrometry (TOF-SIMS). z-corrected 3D images were reconstructed that accurately portray the distribution of intracellular BrdU as well other structures. The localized to nucleus cells, whereas structures composed CxHyOz– species located in bundles on periphery cells. subcellular features had spatial resolution at or slightly below micrometer...
In time-of-flight secondary ion mass spectrometry (ToF-SIMS), the choice of primary used for analysis can influence resulting spectrum. This is because different types produce fragmentation pathways. this study, single-component protein monolayers were performed using monatomic, tri-atomic, and polyatomic sources. Eight ions (Cs(+), Au(+), Au(3) (+), Bi(+), Bi(3) (++), C(60) (+)) to examine low (m/z < 200) patterns from five proteins (bovine serum albumin, bovine fibrinogen, immunoglobulin G...
In dual-beam depth profiling, a high energy analysis beam and lower etching are operated in series. Although the fluence of is usually kept well below static SIMS limit, complete removal damage induced by while maintaining good resolution difficult. this study, plasma polymerized tetraglyme film used as model organic system dimensionless parameter R, (analysis fluence)/(total ion fluence), introduced to quantify degree sample function fluence. For constant C60+ fluence, increasing (and...
The surface sensitivity of Binq+ (n = 1, 3, 5, q 2) and C60q+ (q primary ions in static time-of-flight secondary ion mass spectrometry (TOF-SIMS) experiments were investigated for molecular trehalose polymeric tetraglyme organic films. Parameters related to (impact crater depth, implantation escape depths) measured. Under TOF-SIMS conditions (primary doses 1 × 1012 ions/cm2), the 25 keV Bi1+ most sensitive with a depth 1.8 nm protein films overlayers, but they had deepest (∼18 26 films,...
Age dating of fingerprints could have a significant impact in forensic science, as it has the potential to facilitate judicial process by assessing relevance fingerprint found at crime scene. However, no method currently exists that can reliably predict age latent fingerprint. In this manuscript, time-of-flight secondary ion imaging mass spectrometry (TOF-SIMS) was used measure diffusivity saturated fatty acid molecules from on silicon wafer. It their diffusion relatively fresh (t ≤ 96 h) be...
Passivating surface defects and controlling the carrier concentration mobility in quantum dot (QD) thin films is prerequisite to designing electronic optoelectronic devices. We investigate effect of introducing indium CdSe QD on dark photogenerated lifetime using field-effect transistor (FET) time-resolved microwave conductivity (TRMC) measurements. evaporate ranging from 1 11 nm thickness top approximately 40 thick thiocyanate-capped anneal at 300 °C densify drive diffusion through films....
A novel test sample for the spatially resolved quantification of illicit drugs on surface a fingerprint using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and desorption electrospray ionization (DESI-MS) was demonstrated. Calibration curves relating signal intensity to amount drug deposited were generated from inkjet-printed arrays cocaine, methamphetamine, heroin with deposited-mass ranging nominally 10 pg 50 ng per spot. These used construct concentration maps that visualized...
Abstract Plastic particulates in the environment pose an increasing concern for regulatory bodies due to their potential risk higher organisms (including humans) as they enter food chain. Nanoplastics (defined here smaller than 1 μm) are particularly challenging detect and analyze at environmentally relevant concentrations biological matrices. The tunicate Ciona Robusta is effective bioindicator microplastics nanoplastic contamination marine environment, its capacity filter substantial...
The combination of small coercive fields and weak magnetic anisotropy makes soft ferromagnetic films extremely useful for nanoscale devices that need to easily switch spin directions. However, ferromagnets are relatively rare, particularly in ultrathin with thicknesses a few nanometers or less. We have synthesized large-area, high-quality, freestanding LaMnO3 on Si found unexpected ferromagnetism along both the in-plane out-of-plane directions when film thickness was reduced 4 nm. argue...
Time of flight secondary ion mass spectrometry 2D images and molecular depth profiles human HeLa cells treated with bromodeoxyuridine (BrdU) were acquired in the dual beam mode (Bi(3) (+) analysis beam, C(60) etching beam). Several preparation protocols investigated compared to a simple wash-and-dry method. The feasibility using clean samples prior imaging Bi was also quantitatively by calibrating full atomic force microscopy. BrdU used as marker for cell nucleus, facilitating identification...
Abstract A key open question in the study of layered superconducting nickelate films is role that hydrogen incorporation into lattice plays appearance state. Due to challenges stabilizing highly crystalline square planar films, are prepared by deposition a more stable parent compound which then transformed target phase via topotactic reaction with strongly reducing agent such as CaH 2 . Recent studies, both experimental and theoretical, have introduced possibility from may be critical for...
Organic thin films are of great interest due to their intriguing interfacial and functional properties, especially for device applications such as thin-film transistors sensors. As thickness approaches single nanometer thickness, characterization interpretation the extracted data become increasingly complex. In this study, plasma polymerization is used construct ultrathin that range in from 1 20 nm, time-of-flight secondary ion mass spectrometry coupled with principal component analysis...
Ionic and redox control of magnetism can produce large changes to a variety magnetic properties using relatively small voltage. A model structure that continues be interest is Pt/Co/GdOxHy/Au, where the Co layer oxidation state perpendicular anisotropy toggled voltage proton transport through GdOxHy electrolyte layer. The hydration oxide form hydroxide phase key improve speed these magneto-ionic devices, but there insufficient understanding protonic defect incorporation during electrical...
Abstract In static SIMS experiments, an analysis dose of 10 12 ions/cm 2 typically produces optimum results. However, the same used in dual beam depth profiling can significantly degrade signal. This is because during each cycle a high‐energy rastered across x ‐ y location on sample. If sufficient amount sample not removed sputter cycle, subsequent will volume degraded by previous cycles. The dimensionless parameter, R ′, to relate damage accumulated relative etching beam. Depth profiles...
Background: Small metal nanoparticles obtained from animal blood were observed to be toxic cultured cancer cells, whereas noncancerous cells much less affected. In this work, engineered zinc and copper produced bulk rods by an underwater high-voltage discharge method. The characterized atomic force microscopy X-ray photoelectron spectroscopy. nanoparticles, with estimated diameters of 1 nm–2 nm, determined more than 85% nonoxidized. A cell viability assay high-resolution light showed that...
Olfactory responses are intensely enhanced with the addition of endogenous and engineered primarily-elemental small zinc nanoparticles (NPs). With aging, oxidation these Zn eliminated observed enhancement. The design a polyethylene glycol coating to meet storage requirements is evaluated achieve maximal olfactory benefit. were covered 1000 g/mol or 400 molecular weight (PEG). Non-PEGylated PEGylated tested by electroolfactogram isolated rat epithelium odorant evoked mixture eugenol, ethyl...
Gold deposition on rotating disk electrodes, Bi3+ adsorption planar Au films and superconformal filling of trenches up to 45 μm deep are examined in Bi3+-containing Na3Au(SO3)2 electrolytes with pH between 9.5 11.5. Higher is found increase the potential-dependent rate surfaces, shortening incubation period that precedes active surfaces bottom-up patterned features. Decreased contact angles seeded sidewalls growth front also suggest improved wetting. The dynamic is, however, lost at impact...
We used an ultraviolet-ozone (UVO) cleaner to create substrates for atom-transfer radical polymerization (ATRP) with varying surface initiator coverage. collected complementary time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) measurements investigate the precise chemical origin of variation in grafting density. At short exposure times, atomic composition underwent minor changes except relative amount bromine. longer UVO there is clear...
We show that Au nanoparticles spontaneously move across the (001) surface of InP, InAs, and GaP when heated in presence water vapor. As they move, particles etch crystallographically aligned grooves into surface. this process is a negative analogue vapor–liquid–solid (VLS) growth semiconductor nanowires: dissolves catalyst reacts with vapor at to create volatile oxides, depleting dissolved cations anions thus sustaining dissolution process. This VLS etching provides new tool for directed...
Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) equipped with a bismuth imaging source and an argon gas cluster beam (GCIB) was used to image polished cross‐sections of four automotive multilayer paint samples. Secondary chemical the individual layers possible after GCIB sputter dose (7 × 10 15 ) ions/cm 2 applied for removal polishing residue, at which point composition clear coats could be distinguished using principal components analysis. For differentiation coat chemistries,...
We report the topochemical reduction of epitaxial thin films cubic perovskite BaZrO3. Reduction with calcium hydride yields n-type conductivity in films, despite wide band gap and low electron affinity parent material. X-ray diffraction studies show concurrent loss out-of-plane texture stronger reducing conditions. Temperature-dependent transport on reduced insulating behavior (decreasing resistivity increasing temperature) a combination thermally activated variable-range hopping mechanisms....