A5004161217- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Radioactive element chemistry and processing
- Photochemistry and Electron Transfer Studies
- Crystallography and molecular interactions
- Chalcogenide Semiconductor Thin Films
- Spectroscopy and Quantum Chemical Studies
- Lanthanide and Transition Metal Complexes
- Metal complexes synthesis and properties
- 2D Materials and Applications
- Photochromic and Fluorescence Chemistry
- Organic Electronics and Photovoltaics
- Porphyrin and Phthalocyanine Chemistry
- CO2 Reduction Techniques and Catalysts
- Conducting polymers and applications
- Gas Sensing Nanomaterials and Sensors
- Metal-Catalyzed Oxygenation Mechanisms
- GaN-based semiconductor devices and materials
- Perovskite Materials and Applications
- Organic Light-Emitting Diodes Research
- Metal-Organic Frameworks: Synthesis and Applications
- Antimicrobial agents and applications
- Advanced Sensor and Energy Harvesting Materials
- Laser-Matter Interactions and Applications
- Polymer Surface Interaction Studies
Los Alamos National Laboratory
2021-2024
University of New Mexico
2016-2021
Ohio University
2014-2020
Carrier dynamics in monolayer $\mathrm{Mo}{\mathrm{S}}_{2}$ have been investigated using broadband femtosecond transient absorption spectroscopy (FTAS). A tunable pump pulse was used while a probe revealed ground and excited state carrier dynamics. Interestingly, for wavelengths both resonant nonresonant with the B excitons, we observe broad bleach around 2.9 eV, decay components similar to B. Associating this band nesting region between $K$ \ensuremath{\Gamma} structure indicates...
The phase transformation properties of liquid water to vapor is characterized by optical excitation the lithographically fabricated single gold nanowrenches and contrasted nanoparticles located optically excited in a bulk solution system [two three dimensions]. 532 nm continuous wave nanowrench results superheating spinodal decomposition temperature 580 ± 20 K with bubble formation below being rare event. Between boiling point trapped into metastable state because barrier nucleation exists...
While uranyl-based metal–organic frameworks (MOFs) boast impressive photocatalytic abilities, significant questions remain regarding their excitation pathways and methods to fine-tune performance due the lack of information heterogeneous uranyl catalysis. Herein, we investigated how linker identity photoexcitation impact photocatalysis when coordination environment remains constant. Toward this end, prepared three MOFs (NU-1301, NU-1307, ZnTCPP-U2) then examined structural photochemical...
Thenoyltrifluoroacetone (HTTA)-based extractions represent popular methods for separating microscopic amounts of transuranic actinides (i.e., Np and Pu) from macroscopic actinide matrixes (e.g. bulk uranium). It is well-established that this procedure enables +4 to be selectively removed +3, + 5, +6 f-elements. However, even highly skilled well-trained researchers find process complicated (at times) unpredictable. difficult improve the HTTA extraction-or alternatives-because little...
We report the synthesis and excited-state dynamics for a series of homoleptic copper(I) trifluoromethylated phenanthroline complexes with two, three, four trifluoromethyl functional groups. Our analysis steady-state absorbance emission, transient-absorption spectroscopy, electronic-structure-theory calculations results enable in-depth pseudo-Jahn-Teller distortion inhibition from increased steric hindrance group relative to prototypical dimethyl complex. Surprisingly, our demonstrate that...
A novel Pt-bisacetylide small molecule (Pt-SM) featuring "roller-wheel" geometry was synthesized and characterized. When compared with conventional Pt-containing polymers molecules having "dumbbell" shaped structures, Pt-SM displays enhanced crystallinity intermolecular π-π interactions, as well favorable panchromatic absorption behaviors. Organic solar cells (OSCs) employing achieve power conversion efficiencies (PCEs) up to 5.9%, the highest reported so far for molecules.
We report the synthesis, characterization, and detailed comparison of a series novel Pt-bisacetylide containing conjugated small molecules possessing an unconventional "roller-wheel" shaped structure that is distinctly different from "dumbbell" designs in traditional polymers molecules. The relationships between chemical nature length "rollers" electronic physical properties materials are carefully studied by steady-state spectroscopy, cyclic voltammetry, differential scanning calorimetry,...
Controlling structure and reactivity by manipulating the outer-coordination sphere around a given reagent represents longstanding challenge in chemistry. Despite advances toward solving this problem, it remains difficult to experimentally interrogate characterize impact. This work describes an alternative approach that quantifies effects. It shows how molten salt metal chlorides (MCln; M = K, Na, n 1; Ca, 2) provided excellent platforms for characterizing influence of cations (Mn+) on redox...
Actinide complexation from aqueous acetic acid/acetate buffered solutions is described. The number of water ligands was directly correlated with the acetate concentration and characterized by X-ray absorption optical spectroscopy.
We demonstrate long-lived, multi-mode vibrational dynamics in a class of non-emissive conjugated polymers believed to undergo singlet fission.
Time-resolved transient absorption spectroscopy and computational analysis of D-π-A complexes comprising FeII donors TiIV acceptors with the general formula RCp2Ti(C2Fc)2 (where RCp = Cp*, Cp, MeOOCCp) TMSCp2Ti(C2Fc)(C2R) R Ph or CF3) are reported. The spectra consistent an FeIII/TiIII metal-to-metal charge-transfer (MMCT) excited state for all complexes. Thus, excited-state decay is assigned to back-electron transfer (BET), lifetime which ranges from 18.8 41 ps. Though spectroscopic...
We report the crystallography, emission spectra, femtosecond pump–probe spectroscopy, and density functional theory computations for a series of ruthenium complexes that comprise new class chelating triphenylphosphine based ligands with an appended sulfoxide moiety. These differ only in presence para-substitutent (e.g., H, OCH3, CF3). The results show dramatic range photoisomerization reactivity is ascribed to differences electron phosphine ligand donated nature excited state.
We report the excited-state behavior of a simple <italic>bis</italic>-sulfoxide complex, <italic>cis</italic>-S,S-[Ru(bpy)<sub>2</sub>(dmso)<sub>2</sub>]<sup>2+</sup>, as investigated by femtosecond pump–probe spectroscopy.
Intersystem crossing in conjugated organic molecules is most conveniently viewed from pure electronic perspectives; yet, vibrational displacements may often drive these transitions. We investigate an alkyl-substituted thienylene–vinylene dimer (dTV) displaying efficient triplet formation. Steady-state and Raman spectra display large Stokes shifts (∼4000 cm–1) involving high-frequency skeletal symmetric stretching modes (∼900–1600 addition to of low-frequency torsional motions (∼300–340...
Polydimethylsiloxane (PDMS) polymers containing photochromic ruthenium sulfoxide complexes were prepared. The absorption changes upon light exposure recorded and in the index of refraction calculated from Kramers–Kronig relation. Four-wave mixing experiments performed, demonstrating that an grating can be generated. dynamics angular dependence measured. We determined holographic or photorefractive sensitivity for these materials, which is defined as volume per incident energy (cm3 J–1)....
For solar-driven macroscopic motions, we assert that there is a local heating facilitates large-scale deformations in anisotropic morphologic materials caused by thermal gradients. This report specifically identifies the fate of heat generation photonastic and demonstrates how can perform work following excitation nonisomerizing dye. Utilizing electrospinning technique, have created series nanofibrous polymer mats comprise dyes. Polymers are chosen because their relative glass transition...
Absorption spectroscopy probing transitions from shallow-core d and f orbitals in lanthanides actinides reveals information about bonding the electronic structure compounds containing these elements. However, this photon energy range is challenging because of limited availability light sources extremely short penetration depths. In work, we address challenges using a tabletop extreme ultraviolet (XUV), ultrafast, laser-driven, high harmonic generation source, which generates femtosecond...
We report the photoinduced excited-state dynamics of a series novel Pt(II)-bisacetylide containing conjugated small molecules that possess geometric shapes resembling "roller wheels," but differ in lengths linear chromophores, i.e., "rollers". measure evolution and triplet formation by ultrafast pump probe transient absorption followed quantifying decay lifetimes using nanosecond flash photolysis techniques. Two these complexes relatively longer chromophore smaller bandgaps do not show...
A series of four lanthanide thenoyltrifluoroacetone (TTA) complexes consisting two f0 (La3+ and Ce4+) f1 (Ce3+) was examined using steady-state time-resolved spectroscopic techniques. The wide range techniques presented herein have enabled us to discern the nature excited states (charge transfer, CT vs ligand localized, LL) as well construct a Jablonski diagram for detailing state reactivity within molecules. wavelength excitation power dependence these are first direct verification presence...
The threat of antibiotic-resistant bacteria is an ever-increasing problem in public health. In this report, we examine the photochemical properties with a proof-of-principle biocidal assay for novel series regio-regular imidazolium derivative poly-(3-hexylthiophene)/sodium dodecyl sulfate (P3HT-Im/SDS) materials from ultrafast sub-ps dynamics to μs generation reactive oxygen species (ROS) and 30 min reactivity Escherichia coli (E. coli). This broad encompassing pure P3HT-Im cationic,...
Here we present the solution state structure of thorium( iv ) desferrioxamine (DFO), a bacterial siderophore, and synthesized fluorescent conjugate amenable for imaging.