A5056371618- Mass Spectrometry Techniques and Applications
- Ion-surface interactions and analysis
- Analytical chemistry methods development
- Perovskite Materials and Applications
- Analytical Chemistry and Chromatography
- Conducting polymers and applications
- Additive Manufacturing and 3D Printing Technologies
- Hydrocarbon exploration and reservoir analysis
- Additive Manufacturing Materials and Processes
- Nanopore and Nanochannel Transport Studies
- Minerals Flotation and Separation Techniques
- Manufacturing Process and Optimization
- MXene and MAX Phase Materials
- Force Microscopy Techniques and Applications
- Laser-induced spectroscopy and plasma
- Electrochemical Analysis and Applications
- 2D Materials and Applications
- Advanced Chemical Physics Studies
- Chalcogenide Semiconductor Thin Films
- Spectroscopy Techniques in Biomedical and Chemical Research
- Machine Learning in Materials Science
- Analytical Chemistry and Sensors
- Adhesion, Friction, and Surface Interactions
- Digital Radiography and Breast Imaging
- Polymer Surface Interaction Studies
Oak Ridge National Laboratory
2013-2024
University of Tennessee at Knoxville
2019-2022
National Physical Laboratory
2016-2021
PerkinElmer Biosignal
2021
University of Wuppertal
2003-2019
Center for Nanophase Materials Sciences
2019
Knoxville College
2019
Fraunhofer Institute for Applied Optics and Precision Engineering
2015
University of Bayreuth
2008
Atomically thin two-dimensional (2D) materials face significant energy barriers for synthesis and processing into functional metastable phases such as Janus structures. Here, the controllable implantation of hyperthermal species from pulsed laser deposition (PLD) plasmas is introduced a top-down method to compositionally engineer 2D monolayers. The kinetic energies Se clusters impinging on suspended monolayer WS2 crystals were controlled in <10 eV/atom range with situ plasma diagnostics...
Abstract Mechanical failure of π‐conjugated polymer thin films is unavoidable under cyclic loading conditions, due to intrinsic defects and poor resistance crack propagation. Here, the first tear‐resistant room‐temperature self‐healable semiconducting composite presented, consisting conjugated polymers butyl rubber elastomers. This new displays both a record‐low elastic modulus (<1 MPa) ultrahigh deformability with fracture strain above 800%. More importantly, behavior not sensitive...
Abstract Unique optoelectronic, electronic, and sensing properties of hybrid organic–inorganic perovskites (HOIPs) are underpinned by the complex interactions between electronic ionic states. Here, photoinduced field ion migration in HOIPs is directly observed. Using newly developed local probe time‐resolved techniques, more significant CH 3 NH + than I − /Br unveiled. It found that light illumination only induces but not migration. By observing temporal changes bias‐induced device...
Recently we introduced atmospheric pressure laser ionization (APLI) as a complementary method for coupling LC-MS systems (HPLC and CEC), allowing of nonpolar aromatic compounds via near-resonant two-photon excitation. In this paper, demonstrate that APLI with the same source enclosure LC is also suited hyphenation GC atmospheric-pressure mass spectrometry. This technique permits qualitative quantitative determination in an ultralow concentration range, show here polycyclic hydrocarbons...
Abstract Metal halide perovskite (MHP) solar cells have attracted much attention due to the rapidly growing power conversion efficiency that has reached 25.2% in a decade, comparable established commercial photovoltaic modules. Compositional engineering is one of most effective methods boost performance MHP cells. Further improving and stability necessitates good understanding chemical–efficiency correlation chemical evolution during degradation In this regard, time‐of‐flight secondary ion...
Abstract The instability of hybrid organic–inorganic perovskite (HOIP) devices is one the significant challenges preventing commercialization. Exploring these phenomena severely limited by complexity intrinsic electrochemistry HOIPs, presence multiple volatile and mobile ionic species, possible role environmentally induced reactions at surfaces triple‐phase junctions. Here, in situ studies methylammonium lead bromide with Au electrode interface are reported via light‐ voltage‐dependent...
The gap in understanding how underlying chemical dynamics impact the functionality of metal halide perovskites (MHPs) leads to controversy about origin many phenomena associated with ion migration MHPs. In particular, debate regarding on current-voltage (I-V) hysteresis MHPs devices has lasted for years, where difficulty lies directly uncovering dynamics, as well identifying and separating specific ions. this work, using a newly developed time-resolved time-of-flight secondary mass...
RATIONALE Capture of material from a laser ablation plume into continuous flow stream solvent provides the means for uninterrupted sampling, transport and ionization collected coupling with mass spectral analysis. Reported here is use vertically aligned transmission geometry in combination new non‐contact liquid vortex capture probe coupled electrospray spot sampling chemical imaging spectrometry. METHODS A was positioned directly underneath sample surface (355 nm, 10 Hz, 7 ns pulse width)...
Multimodal chemical imaging simultaneously offers high-resolution and physical information with nanoscale and, in select cases, atomic resolution. By coupling modalities that collect information, we can address scientific problems biological systems, battery fuel cell research, catalysis, pharmaceuticals, photovoltaics, medicine, many others. The combined systems enable the local correlation of material properties makeup, making fundamental questions how chemistry structure drive...
The ammonia monooxygenase (AMO) of Nitrosomonas europaea is a metalloenzyme that catalyses the oxidation to hydroxylamine. We have identified histidine 191 AmoA as binding site for oxidized mechanism-based inactivator acetylene. Binding acetylene changed molecular mass His-191 from 155.15 197.2 Da (+42.05), providing evidence was ketene (CH2CO; 42.04 Da) which binds specifically His-191. It must be assumed part acetylene-activating in AMO or at least directly neighbours this site.
RATIONALE Improvement in spatial resolution of atmospheric pressure molecular chemical imaging is required to resolve distinct surface features the low micrometer and sub‐micrometer scale. Laser capture microdissection systems have capability focus laser light a few micrometers. This type system, when employed for ablation (LA) mass spectrometry (MS)‐based imaging, has potential achieve high with multimodal optical capability. METHODS A commercially available system was coupled modified ion...
Impurity ions influence mineral growth rates through a variety of kinetic and thermodynamic processes that also affect partitioning the impurity ion between solid solution. Here, effect an ion, strontium, on Barite (BaSO4) (001) was studied using combination high-resolution in situ microscopy with ex chemical imaging techniques. In presence ⟨120⟩ steps roughened bifurcated. The overall rate decreased increasing aqueous strontium-to-barium ratio ([Sr]/[Ba]aq) < 1. Analysis reacted solids...
Abstract Mass spectrometry imaging (MSI) plays a pivotal role in investigating the chemical nature of complex systems that underly our understanding biology and medicine. Multiple fields life science such as proteomics, lipidomics metabolomics benefit from ability to simultaneously identify molecules pinpoint their distribution across sample. However, achieving necessary submicron spatial resolution distinguish differences between individual cells generating intact molecular spectra is still...
We present experimental data on the angular distribution of Irganox 1010 organic molecules sputtered by large argon gas cluster projectiles (E/n = 5 eV, 10 keV Ar2000). Ejection probability distributions as derived from deposit patterns planar collector surfaces were recorded at various angles incidence primary ion beam. The material is ejected polar angles, average, greater than 45° surface normal. At normal there no azimuthal dependence in ejecta distribution, but are forward directed even...
Transmission geometry laser ablation directly into a formed liquid microjunction of continuous flow surface sampling probe/electrospray ionization emitter was utilized for molecular and elemental detection mass spectrometry imaging. The ability to efficiently capture ionize ablated material demonstrated by the various small soluble n-mers polyaniline silver ion solvent clusters from electropolymerized thin films, respectively. In addition, analysis surfaces that contain components...
It is demonstrated that spatially resolved mass selected analysis using atmospheric pressure laser ionization spectrometry (APLI MS) represents a new powerful tool for mechanistic studies of ion-molecule chemistry occurring within (AP) ion sources as well evaluation and optimization source performance. A focused low-energy UV beam positioned computer controlled orthogonally on two-dimensional grid in the enclosure. Resonance enhanced multiphoton (REMPI) analytes occurs only confined volume...
Laser ablation provides for the possibility of sampling a large variety surfaces with high spatial resolution. This type when employed in conjunction liquid capture followed by nanoelectrospray ionization opportunity sensitive and prolonged interrogation samples mass spectrometry as well ability to analyze not amenable direct extraction.A fully automated, reflection geometry, laser spot system was achieved incorporating appropriate fiber optics focusing lens into commercially available,...
This paper reports on the advancement of a controlled-resonant surface tapping-mode single capillary liquid junction extraction/ESI emitter for mass spectrometry imaging. The basic instrumental setup and general operation system were discussed, optimized performance metrics presented. ability to spot sample, lane scan, chemically image in an automated controlled fashion demonstrated. Rapid, sampling was demonstrated variety compound types, including cationic dye blue 7, oligosaccharide...
Three-dimensionally (3D) resolved ion trajectory calculations within the complex viscous flow field of an atmospheric pressure source are presented. The model validated with spatially measurements relative sensitivity distribution enclosure, referred to as acceptance (DIA) mass analyzer. In previous work, we have shown that DIA shapes well maximum signal strengths strongly depend on operational parameters such gas flows and temperatures, electrical gradients established by various electrode...
Understanding the impact of environmental gaseous on surface organometal halide perovskites (OMHPs) couples to electronic and ionic transport is critically important. Here, we explore behavior origins gas sensitivity in MAPbBr3 single crystals (SCs) devices using impedance spectroscopy current relaxation measurements. Strong resistive response occurs when are exposed different environments. It was shown that SC environment extremely at as compared bulk due disorder chemistry. The nonlinear...
We introduce a technique for the directed transfer of molecules from an adjacent reservoir onto sample surface inside vacuum chamber ToF-SIMS instrument using gas cluster ion beam (GCIB) sputtering. An example application in situ matrix-enhanced secondary mass spectrometry (ME SIMS) is provided. This protocol has attractive features since most modern SIMS instruments are equipped with GCIB gun. No solvents required that would delocalize analytes at surface, and matrix can be interlaced depth...
We describe the successful coupling of CEC and capillary HPLC with recently developed atmospheric-pressure laser ionization (APLI) method. APLI is suitable for selectively sensitively ionizing nonpolar aromatic compounds at ambient pressure subsequent mass-selective detection. The polycyclic hydrocarbons used as analytes are first separated either by on a silica-based monolithic column or HPLC. eluent, along sheath flow, volatilized microelectrospray then ionized excimer (KrF*) radiation via...