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At least 1,333 records · Page 74
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Nanoscale Editing of Multi and Single Layer Tungsten Disulfide via Gas‐Assisted Focused Electron Beam Induced Etching for Device Prototyping

Focused electron beam induced etching (FEBIE) with XeF 2 (xenon difluoride) precursor is conducted on multi-layer exfoliated WS 2 (tungsten disulfide) and monolayer WS 2 grown by chemical vapor deposition (CVD). The films are characterized by atomic force microscopy (AFM) and Raman and photoluminescence (PL) spectroscopy post-etching. The etch rates/efficiencies are reported as a function of electron beam energy, current, dwell time, and XeF 2 pressure. Bulk film Raman spectra are unchanged post-FEBIE, indicating minimal subsurface damage. Monolayer WS 2 shows a decrease in Raman and PL intensity post-FEBIE, with a dose-to-clear of ≈2 nC µm −2 . The study reveals regimes affected by the various mass transport contributions such as refresh time and the ratio of electrons/XeF 2 . Spontaneous etching was discovered during FEBIE of large patterned areas due to the long frame/refresh times. Density functional theory and ab initio molecular dynamics simulations compares desorption of SF x and WF x molecules from pristine WS 2 basal planes and pore edges, revealing the spontaneous etching is consistent with etching of partially etched monolayers during each frame. Single-line etching width of 21 nm, and patterning flakes into 100 nm wide channels are demonstrated. In conclusion, this work demonstrates the possibility of editing WS 2 flakes into electronic devices of arbitrary dimensions for semiconductor applications.

2D materials↗
DOE OSTI2023

Plasmonic hybrid core-shell (HyCoS) AgPt NP template hybridized with GQDs for SERS enhancement of 4-MBA and BT

Surface-enhanced Raman spectroscopy (SERS) is an attractive vibrational spectroscopic technique that can enable a non-destructive and ultra-sensitive detection down to the single-molecule level. Herein, a novel hybrid SERS platform is developed based on hybrid core-shell (HyCoS) AgPt nanoparticles (NPs) and graphene quantum dots (GQDs) for the enhancement of Raman vibration of 4-mercaptobenzoic acid (4-MBA) and benzenethiol (BT). The unique design of HyCoS AgPt NPs induces strong electromagnetic mechanism (EM) enhancement through the amplification of electromagnetic fields by the excitation of high-density surface plasmons and hot spots. Superior localized surface plasmon resonance (LSPR) is generated by the AgPt core-shell and background Ag NP coupling, which is systematically investigated by the optical properties and FDTD simulations. The background Ag NPs can further increase the coverage of metallic NPs, leading to higher-density hot spots and enhanced SERS response. At the same time, GQDs can provide plentiful accessible edges for the charge transfer to the HOMO and LUMO of 4-MBA and BT based on the chemical mechanism (CM) enhancement. The mixing approach of GQDs and target molecules on the HyCoS AgPt NPs can significantly amplify the Raman signals via the strong adsorption of probe molecules by the π – π interaction. The enhancement factors of proposed SERS platform can reach ~107 and ~105 for the 4-MBA and BT respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Optical vibrational spectra of β -U 3 O 8

Technogenic uranium oxides are ubiquitous in the nuclear fuel cycle. Identifying the chemical composition of these oxides is frequently done with optical vibrational spectroscopy (infrared and Raman spectroscopy). The α phase of U 3 O 8 is the most stable and common uranium oxide, but a β phase of U 3 O 8 can be produced via very slow cooling of the α phase from elevated temperatures or the application of small shear forces. However, optical spectra of this compound have not been reported. In this work, we use high-resolution attenuated total reflection infrared spectroscopy and Raman spectroscopy to collect the optical vibrational spectra. Despite similarities in the crystal structure of α and β – U 3 O 8 , the optical spectra of these compounds differ substantially, with additional Raman active modes in β – U 3 O 8 that are likely originating from differences in the U–O coordination units. Measurements presented here provide spectral characterization that can be used for chemical identification in future studies of uranium oxides.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Analytical workflow dependence of experimental observables for uranium chemistries

In this work, we investigated how the sequencing of laboratory analytical methods used for chemical and morphological characterization influences analytical findings for particulate materials relevant to the nuclear fuel cycle, including UO2, U3O8, studtite (UO2O2·4H2O), and β-UO3, in the context of nuclear forensic analysis. Particles of each chemistry obtained from consistent production batches were exposed to Raman spectroscopy and scanning electron microscopy in varying orders to elucidate how the order in which the techniques are applied influences morphological and chemical observations as a function of particle size. The results indicate that particles from all four chemistries exposed to high-resolution electron imaging before Raman spectral analysis demonstrate optical vibrational spectral changes that reduce accurate interpretation of the underlying chemistry via Raman spectral analysis. We hypothesize that these changes are due to the thermal load of the electron beam imparted to the sample being unable to be dissipated by materials with poor thermal conduction properties. Results from this study will aid in determining best practices for forensic analysis procedures to reduce uncertainty in chemical determination of unknown particulate samples.

Manns, Rebecca [University of Nevada, Las Vegas]↗
DOE OSTI2022

Hybrid SERS platform by adapting both chemical mechanism and electromagnetic mechanism enhancements: SERS of 4-ATP and CV by the mixture with GQDs on hybrid PdAg NPs

Surface-enhanced Raman spectroscopy (SERS) is a versatile analytical technique widely adapted for the identification of target analytes even at an extremely low concentration. Herein, a unique hybrid SERS platform is demonstrated by utilizing the graphene quantum dots (GQDs) and hybrid PdAg NPs for the detection of 4-amino-thiophenol (4-ATP) and crystal violet (CV). GQDs offer the rich charge transfer to the LUMO and HOMO of 4-ATP and CV by the CM enhancement. A significant EM enhancement is achieved by the strong localized surface plasmon resonance (LSPR) of uniquely designed hybrid core-shell PdAg NP, possessing the narrow nano-gaps with the highly dense small Ag NPs and Pd core Ag shell configuration. As a result, orders of enhancement of originally weak 4-ATP and CV Raman signal is witnessed by the combination of electromagnetic mechanism (EM) and chemical mechanism (CM) enhancements on a single SERS substrate. The hybrid GQD/HNP SERS substrate demonstrates significantly improved hot spots and strongly localized electromagnetic fields as confirmed by the finite-difference time-domain (FDTD) simulations. There for a proper mixture ratio of GQDs and probe molecules presents largely enhanced SERS signals by a strong adsorption of probe molecules through π - π interaction and the enhancement factors vary by the mixture ratio depending on the adsorption kinetics and Raman cross-section of molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Vibrational spectroscopy of uranium tetrafluoride hydrates

Uranium tetrafluoride (UF 4 ) is an important intermediate in the production of UF6 and nuclear fuel. Historical characterization of UF 4 with Raman spectroscopy was plagued with ambiguity until the first accurate Raman spectrum was published by our group in 2016. Although generally considered to be relatively stable, UF 4 can hydrolyze to form numerous UF 4 hydrates that may play a role in future uranium waste forms. In contrast to anhydrous UF 4 , the hydrates, with their OH stretch and HOH bending modes, can be spectroscopically characterized by the type and degree of water bonding in the crystal lattice, which can yield additional information about their crystal structure. Herein, vibrational spectroscopy (Raman and infrared) was used to characterize three different UF 4 hydrates: UF 4 (H 2 O) 0.33 , U 3 F 12 (H 2 O), and UF 4 (H 2 O) 2.5 . Spectra show the different hydrates vary in the number of observed bands, full-width half-maximum of the bands, and band intensity. These differences are due to varying interactions between the OH stretch and HOH bending modes with UF 4 and the polymeric UF 4 structure in the crystal lattice. These vibrational data, in combination with spectral fitting and crystallographic structures measured with powder X-ray diffraction and single crystal X-ray diffraction, provide unique details on the location of water molecules in the crystal lattice of hydrated UF 4 , and provide an interesting contrast to the vibrational spectra of anhydrous UF 4 .

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Online, real-time analysis of highly complex processing streams: Quantification of analytes in Hanford tank sample

Processing of hazardous materials is a crucial example of where on-line monitoring can significantly reduce operation risk, cost, and time. This is particularly true in the case of the Hanford site, where nuclear materials from the cold war era are being processed for environmental cleanup efforts. In exceedingly complex streams such as those at Hanford, on-line and real-time monitoring can be a challenge due to complexity of signals. Further obstacles are imposed by the caustic nature of processing streams as well as the radiation damage inflicted on instruments and probes. On-line monitoring based on Raman spectroscopy enables the detection of many Hanford tank species of interest, and was demonstrated here on nine chemical species that comprise the majority of tank waste by volume, including Al(OH)4-, C2O42-, CO32-, CrO42-, NO32-, NO3-, OH-, PO43-, SO42-. Real-time analysis of Raman signal allows for immediate quantification of target analytes and was successfully accomplished through the use of chemometric models. Furthermore, irradiation tests reveal Raman monitoring systems can effectively continue to operate even after receiving 1·107 Rad of gamma dose. The on-line, real-time monitoring system developed here was successfully used to simultaneously quantify nine target analytes in a real samples collected from Hanford tank AP-105.

Lines, Amanda M.↗
DOE OSTI2022

Gamma-Ray-Induced Formation of Uranyl Peroxide Cage Clusters

Aqueous solutions of lithium uranyl triperoxide, Li 4 [UO 2 (O 2 ) 3 ] (LiUT), were irradiated with gamma rays at room temperature and found to form the uranyl peroxide cage cluster, Li 24 [(UO 2 )(O 2 )(OH)] 24 (Li–U 24 ). Raman spectroscopy and 18 O labeling were used to identify the Raman-active vibrations of LiUT. With these assignments, the concentration of LiUT was tracked as a function of radiation dose. A discrepancy between monomer removal and cluster formation suggests that the reaction proceeds by the assembly of an intermediate. Non-negative matrix factorization was used to separate Raman spectra into components and resulted in the identification of a unique intermediate species. Much of the conversion appears to be driven by water radiolysis products, particularly the hydroxyl radical. Furthermore, this differs from the 18 O-labeled copper-catalyzed formation of U 24 , which progresses at a steady rate with no observation of intermediates. Li–U 24 in solution decomposes at high radiation doses resulting in a solid insoluble product similar to Na-compreignacite, Na 2 (UO 2 ) 6 O 4 (OH) 6 ·7H 2 O, which contains uranyl oxyhydroxy sheets.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Spectroscopic Characterization of $μ$-$η$ 1 :$η$ 1 -Peroxo Ligands Formed by Reaction of Dioxygen with Electron-Rich Iridium Clusters

Although oxygen is a common ligand in supported metal catalysts, its coordination has been challenging to elucidate. Herein we characterize a diiridium complex that has been previously shown by X-ray diffraction crystallography to incorporate a μ-η 1 :η 1 -peroxo ligand. We observe markedly enhanced intensity at 788 cm -1 in the Raman spectrum of this complex, which is a consequence of bonding of the peroxo ligand but does not shift upon 18 O labeling. Electronic structure calculations at the density functional theory level suggest that this increase in Raman intensity results from bands associated with rocking of CH 2 substituents directly attached to P(Ph) 2 groups coupling with the O-O band. These results provide part of the foundation for understanding oxygen ligands on a silica-supported tetrairidium carbonyl cluster stabilized with bulky electron-donating phosphine ligands [ p-tert -butyl-calix[4]arene(OPr) 3 (OCH 2 PPh 2 ) (Ph = phenyl; Pr = propyl)]. Reaction of the cluster with O2 also led to the growing in of a Raman band at 788 cm -1 , similar to that in the diiridium complex and also assigned to the bonding of a bridging peroxo ligand. Infrared spectra recorded as the supported cluster reacted in sequential exposures to (i) H 2 , (ii) O 2 , (iii) H 2 , and (iv) CO indicate that two bridging peroxo ligands were bonded irreversibly per tetrairidium cluster, replacing bridging carbonyl ligands without altering either the cluster frame or the phosphine ligands. X-ray absorption near edge and infrared spectra include isosbestic points signifying a stoichiometrically simple reaction of the cluster with O 2 , and mass spectra of the effluent gas show that CO 2 formed by oxidation of one terminal CO ligand per cluster as H 2 (and not H 2 O) formed, evidence that hydride ligands had been present on the cluster following treatment (i). The understanding of how O 2 reacts with the metal polyhedron provides a foundation for understanding of how oxidation catalysis may proceed on the surfaces of noble metals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Enhanced Formation of Solvent-Shared Ion Pairs in Aqueous Calcium Perchlorate Solution toward Saturated Concentration or Deep Supercooling Temperature and Its Effects on the Water Structure

As a candidate of Martian salts, calcium perchlorate [Ca(ClO 4 ) 2 ] has the potential to stabilize liquid water on the Martian surface because of its hygroscopicity and low freezing temperature when forming aqueous solution. These two properties of electrolytes in general have been suggested to result from the specific cation–anion–water interaction (ion pairing) that interrupts the structure of solvent water. To investigate how this concentration-dependent and temperature-dependent ion pairing process in aqueous Ca(ClO 4 ) 2 solution leads to its high hygroscopic property and the extreme low eutectic temperature, we have conducted two sets of experiments. First, the effects of concentration on aqueous calcium perchlorate from 3 to 7.86 m on ion pairing were investigated using Raman spectroscopy. Deconvolution of the Raman symmetric stretching band (ν 1 ) of ClO 4 – showed the enhanced formation of solvent-shared ion pairs upon increasing salt concentration at room temperature. We have confirmed that the low tendency of forming contact ion pairs in concentrated solution contributes to the high hygroscopicity of the salt. Second, the near eutectic samples were studied as a function of temperature by both combined differential scanning calorimetry–Raman spectroscopic experiments and in situ X-ray diffraction. The number of solvent-shared ion pairs was found to increase with decreasing temperature when cooled below the temperature of maximum density of the solution, driven by a change in water toward an ice-like structure in the supercooled regime. The massive presence of solvent-shared ion pairs in turn limits the development of the long-range order in the tetrahedral networks of water molecules, which is responsible for the extremely low eutectic point and deep supercooling effects observed in the Ca(ClO 4 ) 2 –H 2 O system.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Bridging Structure, Magnetism, and Disorder in Iron-Intercalated Niobium Diselenide, Fe x NbSe 2 , below x = 0.25

Transition-metal dichalcogenides (TMDs) intercalated with magnetic ions serve as a promising materials platform for developing next-generation, spin-based electronic technologies. In these materials, one can access a rich magnetic phase space depending on the choice of intercalant, host lattice, and relative stoichiometry. The distribution of these intercalant ions across given crystals, however, is less well defined–particularly away from ideal packing stoichiometries–and a convenient probe to assess potential longer-range ordering of intercalants is lacking. Here, we demonstrate that confocal Raman spectroscopy is a powerful tool for mapping the onset of intercalant superlattice formation in Fe-intercalated NbSe 2 (Fe x NbSe 2 ) for 0.14 ≤ x < 0.25. We use single-crystal X-ray diffraction to confirm the presence of longer-range intercalant superstructure and employ polarization-, temperature-, and magnetic field-dependent Raman measurements to examine both the symmetry of emergent phonon modes in the intercalated material and potential magnetoelastic coupling. Magnetometry measurements further indicate a correlation between the onset of magnetic ordering and the relative degree of intercalant superlattice formation. These results show Raman spectroscopy to be an expedient, local probe for mapping intercalant ordering in this class of magnetic materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Oxide-Free Three-Dimensional Germanium/Silicon Core–Shell Metalattice Made by High-Pressure Confined Chemical Vapor Deposition

Metalattices are crystalline arrays of uniform particles in which the period of the crystal is close to some characteristic physical length scale of the material. In this work, we explore the synthesis and properties of a germanium metalattice in which the similar to 70 nm periodicity of a silica colloidal crystal template is close to the similar to 24 nm Bohr exciton radius of the nanocrystalline Ge replica. The problem of Ge surface oxidation can be significant when exploring quantum confinement effects or designing electronically coupled nanostructures because of the high surface area to volume ratio at the nanoscale. To eliminate surface oxidation, we developed a coreshell synthesis in which the Ge metalattice is protected by an oxide-free Si interfacial layer, and we explore its properties by transmission electron microscopy (TEM), Raman spectroscopy, and electron energy loss spectroscopy (EELS). The interstices of a colloidal crystal film grown from 69 nm diameter spherical silica particles were filled with polycrystalline Ge by high-pressure confined chemical vapor deposition (HPcCVD) from GeH4. After the SiO2 template was etched away with aqueous HF, the Ge replica was uniformly coated with an amorphous Si shell by HPcCVD as confirmed by TEM-EDS (energy-dispersive X-ray spectroscopy) and Raman spectroscopy. Formation of the shell prevents oxidation of the Ge core within the detection limit of XPS. The electronic properties of the core-shell structure were studied by accessing the Ge 3d edge onset using STEM-EELS. A blue shift in the edge onset with decreasing size of Ge sites in the metalattices suggests quantum confinement of the Ge core. The degree of quantum confinement of the Ge core depends on the void sizes in the template, which is tunable by using silica particles of varying size. The edge onset also shows a shift to higher energy near the shell in comparison with the Ge core. This shift along with the observation of Ge-Si vibrational modes in the Raman spectrum indicate interdiffusion of Ge and Si. Both the size of the voids in the template and core-shell interdiffusion of Si and Ge can in principle be tuned to modify the electronic properties of the Ge metalattice.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Optimizing performance and yield of vertical GaN diodes using wafer scale optical techniques

Abstract To improve the manufacturing of vertical GaN devices for power electronics applications, the effects of defects in GaN substrates need to be better understood. Many non-destructive techniques including photoluminescence, Raman spectroscopy and optical profilometry, can be used to detect defects in the substrate and epitaxial layers. Raman spectroscopy was used to identify points of high crystal stress and non-uniform conductivity in a substrate, while optical profilometry was used to identify bumps and pits in a substrate which could cause catastrophic device failures. The effect of the defects was studied using vertical P-i-N diodes with a single zone junction termination extention (JTE) edge termination and isolation, which were formed via nitrogen implantation. Diodes were fabricated on and off of sample abnormalities to study their effects. From electrical measurements, it was discovered that the devices could consistently block voltages over 1000 V (near the theoretical value of the epitaxial layer design), and the forward bias behavior could consistently produce on-resistance below 2 mΩ cm 2 , which is an excellent value considering DC biasing was used and no substrate thinning was performed. It was found that high crystal stress increased the probability of device failure from 6 to 20%, while an inhomogeneous carrier concentration had little effect on reverse bias behavior, and slightly (~ 3%) increased the on-resistance (R on ). Optical profilometry was able to detect regions of high surface roughness, bumps, and pits; in which, the majority of the defects detected were benign. However a large bump in the termination region of the JTE or a deep pit can induce a low voltage catastrophic failure, and increased crystal stress detected by the Raman correlated to the optical profilometry with associated surface topography.

42 ENGINEERING↗
DOE OSTI2020

Selectively accessing the hotspots of optical nanoantennas by self-aligned dry laser ablation

Plasmonic nanostructures serve as optical antennas for concentrating the energy of incoming light in localized hotspots close to their surface. By positioning nanoemitters in the antenna hotspots, energy transfer is enabled, leading to novel hybrid antenna-emitter-systems, where the antenna can be used to manipulate the optical properties of the nano-objects. The challenge remains how to precisely position emitters within the hotspots. We report a self-aligned process based on dry laser ablation of a calixarene that enables the attachment of molecules within the electromagnetic hotspots at the tips of gold nanocones. Within the laser focus, the ablation threshold is exceeded in nanoscale volumes, leading to selective access of the hotspot areas. A first indication of the site-selective functionalization process is given by attaching fluorescently labelled proteins to the nanocones. In a second example, Raman-active molecules are selectively attached only to nanocones that were previously exposed in the laser focus, which is verified by surface enhanced Raman spectroscopy. Enabling selective functionalization is an important prerequisite e.g. for preparing single photon sources for quantum optical technologies, or multiplexed Raman sensing platforms.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

Spatially resolved multimodal vibrational spectroscopy under high pressures

In this perspective, we discuss the potential impact on in situ studies under controlled environments of a novel multimodal spectroscopic technique, optical photothermal infrared + Raman spectroscopy, which enables the simultaneous collection of infrared and Raman scattering spectra, along with hyperspectral imaging and chemical imaging with wavelength-independent sub-500 nm spatial resolution. A brief review of the current literature regarding the O-PTIR technique is presented along with recent work from our own lab on determining the crystallinity of soft and inorganic materials. The results highlight the possibility of resolving differences in the crystallinity of soft materials associated with changes in material processing. Here, we also demonstrate the first reported use of a diamond anvil cell with simultaneous infrared and Raman measurements that showcases, using a high energy material as an example, the potential use of O-PTIR spectroscopy in diamond anvil cell techniques.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Thermal decomposition of neptunyl ammonium nitrate: mechanistic insights and structural characterization of the Np 2 O 5 intermediate phase

Neptunium (Np) possesses a rich and unique chemistry that often diverges from other actinide elements yet remains relatively underexplored compared with the other light actinides. A resurgence of interest in Np has been spurred by the application of 237 Np for plutonium-238 ( 238 Pu) production for use in radioisotope thermoelectric generators (RTGs), necessitating evaluation of Np chemical reactions and materials. The work presented here studied the thermal decomposition of neptunyl ammonium nitrate (NH 4 Np VI O 2 (NO 3 ) 3 ) for synthesis of neptunium dioxide (NpO 2 ), which is the target material used for production of 238 Pu. Additionally, structural characterization of the intermediate solid Np pentoxide (Np 2 O 5 ) was performed. Advanced solid-state characterization techniques, including simultaneous thermal analysis (STA), powder X-ray diffraction (pXRD), Raman spectroscopy, and density functional theory (DFT) modeling have been combined to study the reaction pathways. Analysis revealed that NH 4 Np VI O 2 (NO 3 ) 3 thermally decomposes to a proposed neptunyl nitrate intermediate, followed by Np 2 O 5 and finally NpO 2 , all within the temperature range of 150 °C–600 °C. Further characterization of the pentoxide intermediate provided the first Raman spectra of pure-phase Np 2 O 5 and associated DFT modeling confirmed Raman peak assignments for this phase. These findings provide mechanistic information to advance production of the critical radioisotope 238 Pu and advance the state of knowledge on Np materials chemistry using modern characterization techniques.

Lawson, Kathryn M. [Oak Ridge National Laboratory ↗
DOE OSTI2026

Modern insights into the mechanisms of neptunium oxalate decomposition

Neptunium oxalate (Np(C 2 O 4 ) 2 ·6H 2 O) is a historically relevant solid phase used in nuclear processing as a precursor for neptunium dioxide (NpO 2 ). Although Np oxalate has been synthesized and used for NpO 2 production for decades, the thermal decomposition mechanism of this phase remains poorly understood and has not been evaluated in over 30 years. Conflicting reports in historical literature suggest either a direct conversion from anhydrous oxalate to NpO 2 or a decomposition that includes the formation of Np carbonate or oxidized Np intermediate phases. In this work, we reexamine the decomposition pathway of Np(C 2 O 4 ) 2 ·6H 2 O using thermal analysis coupled with evolved gas analysis and temperature-dependent Raman spectroscopy to elucidate decomposition mechanisms and intermediate phases using modern analytical techniques. Thermal analysis revealed a three-stage decomposition process, including dehydration below 200 °C, oxalate breakdown between 170 and 370 °C, and NpO 2 formation by 500 °C. However, an unidentified plateau in the thermal data was observed during measurements. Raman spectroscopy confirmed the stages of decomposition, and in the analysis of potential intermediate phases, no carbonate phases or Np 2 O 5 were identified. Raman data suggest that residual oxalate or nonstoichiometric oxide are present during decomposition before pure NpO 2 is formed. These findings clarify aspects of the Np oxalate decomposition mechanism and address longstanding discrepancies in the literature, with a specific focus on Np-specific materials chemistry.

Lawson, Kathryn M. [Oak Ridge National Laboratory ↗