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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Characterization of Build Parameters and Microstructure in Low Heat Input WAAM of Ni-Based Superalloy Haynes 282

Ni-based superalloy Haynes® 282® is being targeted for various applications in advanced power generation systems for its superior fabricability, weldability, and excellent high temperature creep and corrosion performance. This process optimization study aims to use a low heat-input, high deposition rate, controlled Gas Metal Arc Welding (GMAW) process, Cold Metal Transfer (CMT) by Fronius, attempting to achieve fully dense fabrication and possibly avoid the need for HIP. Twenty-one multilayer blocks (~25x100x40 mm3) were deposited to explore a large set of build parameters variations that focused on varying the travel speed from 14 to 42 inches per minute (ipm) and wire feed speed from 150 to 450 ipm. A strong correlation has been observed between arc energy – controlled primarily by travel and wire feed speed. Initial visual inspection, internal microstructural examination, and computed tomography (CT) have been used to determine the effects of built parameters on evolution of internal porosity and defects. Scanning electron microscopy techniques enabled structural and compositional imaging of heterogeneity and changes in microstructural properties.

additive manufacturing↗
NASA NTRS1977

Auger spectroscopy analysis in adhesion, friction and wear studies

The paper reviews the current use of Auger electron spectroscopy in adhesion, friction, wear and lubrication studies. Conventional Auger spectroscopy is adopted to complement LEED studies of the adhesion of metal single crystals. In addition, Auger cylindrical mirror analysis is applied to the study of changes in surface chemistry during dynamic friction and wear experiments on polycrystalline metals and alloys. Important conclusions are that (1) segregation of alloying elements to the surface of metals can alter adhesion behavior; (2) hydrocarbons are adsorbed readily to clean iron surfaces at 23 C; (3) transfer from one surface to another for dissimilar materials in contact can be followed in sliding or rubbing friction studies; and (4) the friction process can enhance surface activity for metals with hydrocarbons.

Buckley, D. H.↗
NASA NTRS1999

Microgravity Transport Phenomena Experiment (MTPE) Overview

The Microgravity Transport Phenomena Experiment (MTPE) is a fluids experiment supported by the Fundamentals in Biotechnology program in association with the Human Exploration and Development of Space (BEDS) initiative. The MTP Experiment will investigate fluid transport phenomena both in ground based experiments and in the microgravity environment. Many fluid transport processes are affected by gravity. Osmotic flux kinetics in planar membrane systems have been shown to be influenced by gravimetric orientation, either through convective mixing caused by unstably stratified fluid layers, or through a stable fluid boundary layer structure that forms in association with the membrane. Coupled transport phenomena also show gravity related effects. Coefficients associated with coupled transport processes are defined in terms of a steady state condition. Buoyancy (gravity) driven convection interferes with the attainment of steady state, and the measurement of coupled processes. The MTP Experiment measures the kinetics of molecular migration that occurs in fluids, in response to the application of various driving potentials. Three separate driving potentials may be applied to the MTP Experiment fluids, either singly or in combination. The driving potentials include chemical potential, thermal potential, and electrical potential. Two separate fluid arrangements are used to study membrane mediated and bulk fluid transport phenomena. Transport processes of interest in membrane mediated systems include diffusion, osmosis, and streaming potential. Bulk fluid processes of interest include coupled phenomena such as the Soret Effect, Dufour Effect, Donnan Effect, and thermal diffusion potential. MTP Experiments are performed in the Microgravity Transport Apparatus (MTA), an instrument that has been developed specifically for precision measurement of transport processes. Experiment fluids are contained within the MTA fluid cells, designed to create a one dimensional flow geometry of constant cross sectional area, and to facilitate fluid filling and draining operations in microgravity. The fluid cells may be used singly for bulk solutions, or in a Stokes diaphragm configuration to investigate membrane mediated phenomena. Thermal and electrical driving potentials are applied to the experiment fluids through boundary plates located at the ends of the fluid cells. In the ground based instrument, two constant temperature baths circulate through reservoirs adjacent to the boundary plates, and establish the thermal environment within the fluid cells. The boundary plates also serve as electrodes for measurement and application of electrical potentials. The Fluid Manipulation System associated with the MTA is a computer controlled system that enables storage and transfer of experiment fluids during on orbit operations. The system is used to automatically initiate experiments and manipulate fluids by orchestrating pump and valve operations through scripted sequences. Unique technologies are incorporated in the MTA for measurement of fluid properties. Volumetric Flow Sensors have been developed for precision measurement of total fluid volume contained within the fluid cells over time. This data is most useful for measuring the kinetics of osmosis, where fluid is transported from one fluid cell to another through a semipermeable membrane. The MicroSensor Array has been designed to perform in situ measurement of several important fluid parameters, providing simultaneous measurement of solution composition at multiple locations within the experiment fluids. Micromachined sensors and interface electronics have been developed to measure temperature, electrical conductivity, pH, cation activity, and anion activity. The Profile Refractometer uses a laser optical system to directly image the fluid Index of Refraction profile that exists along the MTA fluid cell axis. A video system acquires images of the RI profile over time, and records the transport kinetics that occur upon application of chemical, thermal, or electrical driving potentials. Image processing algorithms have been developed to analyze the refractometer images on a pixel by pixel basis, calibrating and scaling the measured Index of Refraction profile to correlated solution properties of interest such as density, concentration, and temperature. Additional software has been developed to compile the processed images into a three dimensional matrix that contains fluid composition data as a function of experiment time and position in the fluid cell. These data are combined with data from the other sensor systems, and analyzed in the context of transport coefficients associated with the various transport phenomena. Analysis protocols have been developed to measure the transient kinetics, and steady state distribution of fluid components that occur in response to the applied driving potentials. The results are expressed in terms of effective transport coefficients. Experiments have been performed using a variety of solutes, and results generated are that are in agreement with published transport coefficient values.

Mason, Larry W.↗
DOE OSTI2023

Beneficial Effects of La 0.5 Sr 0.5 CoO 3 Coatings on Thin‐Film LiMn 2 O 4 Cathodes for Lithium Ion Batteries

Abstract The severe capacity loss of spinel LiMn 2 O 4 (LMO) limits the utility of this otherwise promising lithium ion battery cathode material. One of the strategies to mitigate capacity fade is applying a coating on LMO particle surfaces. While this approach yields promising results, there is limited understanding of mechanisms whereby coatings improve LMO capacity retention. Herein, the effects of a new protective coating material, La 0.5 Sr 0.5 CoO 3 (LSCO), in a thin‐film battery geometry that is amenable to fundamental studies of electrode processes, are reported. RF sputtering deposition is used to produce high quality 25–100 nm LMO cathodes on Al 2 O 3 substrates with an intervening Pt/Ti back‐side contact layer. Cycling of the un‐coated cathodes results in capacity loss of 18% over 300 cycles. Adding a 2 nm LSCO layer reduces the capacity loss to 3%. While this may be due in part to reduced Mn dissolution, scanning transmission electron microscopy results indicate that the coating helps to preserve crystallinity and reduce lattice structure distortion due to inhibited formation of defect tetragonal spinel. Three‐electrode electrochemical impedance spectroscopy results reveal that the LSCO coating increases charge transfer and ohmic resistances, but the increases are generally too small to significantly impact cell performance even at high C‐rates.

25 ENERGY STORAGE↗
DOE OSTI2022

Low temperature ethanol steam reforming: Selectivity control with lithium doping of Pt/m-ZrO 2

Lithium promoted 2%Pt/m-ZrO 2 catalysts previously observed to exhibit higher rates for the low temperature water-gas shift (LTS) were tested for the ethanol steam reforming with the aim of exploring the potential tuning of the selectivity. Characterization of catalysts having optimized Li content (0.5–0.75%Li) for LTS exhibited (a) weakened C—H bonding of formate, a proposed intermediate in the LTS mechanism, as shown by a shift in the ν(CH) band to lower wavenumbers, (b) a relatively low extent of blocking of Pt, as measured by the ν(CO) band intensity of Pt-CO, (c) increased basicity as measured by CO 2 temperature-programmed desorption with mass spectrometry, but not so high as to strongly inhibit CO 2 product removal, and finally (d) no evidence of electron transfer from Li to Pt. Here, for this study, the same catalysts were tested for ethanol steam reforming (ESR). Results show that Li could likewise weaken the C—C bond of the acetate intermediate, the analog of formate in LTS, and facilitate decarboxylation over decarbonylation altering the selectivity in favor of methanation. This trend was confirmed by fixed bed reaction testing, in-situ infrared spectroscopy experiments of transient ESR, and temperature-programmed ESR using MS. The Li-doped catalysts may be used to pre-reform ethanol prior to feeding to a methane steam reformer to increase the overall H 2 selectivity of the process. DRIFTS of steady state ESR revealed that deactivation occurs through losses in the Pt-support interface, thereby hindering the turnover of the acetate intermediate.

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

Final Report: Next Generation Diamond Drumhead X-Ray Optics

Problem / Opportunity Statement: Future high-impact scientific applications at synchrotron and Free-Electron Laser (FEL) X-ray sources require the development of processing and mounting methods for ultra-thin diamond crystals to meet the most challenging needs of pioneering research at next generation light source facilities. These methods should be capable of manufacturing crystal plates as thin as 10 micrometers over an area of a few mm2, and with a surface cut in different crystal orientations, such as the diamond {100}, {111}, {110} and {113} planes. Project Purpose and Approach: In Phase I, Great Lakes Crystal Technologies (GLCT) partnered with Stonybrook University (SUNY) to created thin diamond drumhead crystals. The purpose of the Phase I project is to transfer the drumhead membrane window etching technology from SUNY to GLCT. Testing of a device using the beamline at Stanford Linear Accelerator Laboratory was initially planned, however, a delay on the part of a third party service provided required us to get beamline testing done at Argonne National Laboratory. Phase I Taskwork: Testing of a high purity diamond plate thinning and etching process was performed. By SUNY and GLCT. Plates were sent to a third party service provider for thinning to ~100 microns, however, delays required that GLCT develop an in-house thinning process to complete the taskwork. GLCT successfully developed this in-house capability even though it was initially planned to be part of the Phase II Taskwork. Multiple practice and deliverable plates were provided to SUNY to be etched into the target drumhead devices. GLCT practiced and refined an in-house plate thinning process and produced five plates with thicknesses in the 60 – 150 micron range. Processing of the plates has begun and will continue in a no-cost extension period necessitated by the third party service provider delay. GLCT also procured and installed a reactive ion etching/inductively coupled plasma system. In addition, one of the thinned plates was measured at the Applied Photon Source at APL for a pre-processing assessment of the crystalline strain. After processing the plate into a drumhead and annealing, a post-processing assessment of the strain will be performed. Phase I Results: The initial data from GLCT’s plate thinning process development, SUNY’s drumhead etching processing, and characterization at APS/ANL demonstrate our teams capabilities to achieve the project goals. Commercial Applications & Benefits: The proposed technology will benefit advanced x-ray science performed at BNL and the 70+ additional advanced beamlines around the world. There are also a number of medical and homeland security applications which could benefit from the technology.

Quayle, Paul↗
NASA NTRS2011

Prospects for Interdisciplinary Science Aboard the International Space Station

The assembly of the International Space Station was completed in early 2011, and is now embarking on its first year of the coming decade of use as a laboratory. Two key types of physical science research are enabled by ISS: studies of processes that are normally masked by gravity, and instruments that take advantage of its position as a powerful platform in orbit. The absence of buoyancy-driven convection enables experiments in diverse areas such as fluids near the critical point, Marangoni convection, combustion, and coarsening of metal alloys. The positioning of such a powerful platform in orbit with robotic transfer and instrument support also provides a unique alternative platform for astronomy and physics instruments. Some of the operating or planned instruments related to fundamental physics on the International Space Station include MAXI (Monitoring all-sky X-ray Instrument for ISS), the Alpha Magnetic Spectrometer, CALET (Calorimetric Electron Telescope), and ACES (Atomic Clock Experiment in Space). The presentation will conclude with an overview of pathways for funding different types of experiments from NASA funding to the ISS National Laboratory, and highlights of the streamlining of services to help scientists implement their experiments on ISS.

Robinson, Julie A.↗
DOE OSTI2025

Intrinsic property of defective β-Ga 2 O 3 to self-heal under ionizing irradiation

Damage evolution and phase stability in defective β-Ga 2 O 3 and an irradiation-converted γ-Ga 2 O 3 layer have been studied under ionizing irradiation at 300 K. By exploring athermal nonequilibrium processes in β-Ga 2 O 3 , we succeed in identifying a self-healing mechanism that enables recovery pre-existing damage, characterized by a recovery cross-section of ~0.17 nm 2 . Remarkably, this study further demonstrates that the crystallinity of the irradiation-converted γ-Ga 2 O 3 layer improves under ionizing irradiation. More importantly, X-ray diffraction analysis reveals that the highly-strained 𝛾 -phase transforms into a highly-crystalline structure without film disintegration, contrasting to that reported for isochronal annealing at 1000 K. The inelastic thermal spike calculations provide insights into the important effects of energy transfer to electrons in reordering the local atomic arrangement of both defective β- Ga 2 O 3 and 𝛾-Ga 2 O 3 . This behavior suggests a pathway for low-temperature crystallization, offering a promising strategy for fabricating ultrahigh-speed non-volatile memory devices.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Spin-on deposition of amorphous zeolitic imidazolate framework films for lithography applications

Amorphous zeolitic imidazolate framework (aZIF) films have been recently introduced as resists for electron beam and extreme ultraviolet lithography. aZIFs are also being considered for separation applications, including thin film membranes. However, the reported methods for aZIF deposition are currently based on highly empirical trial-and-error approaches that hinder control of film composition, thickness and uniformity as well as scale-up and transferability to different coating geometries. This work presents a method for depositing aZIF films with controllable thickness using dilute precursors mixed immediately before encountering the substrate. Importantly, the method is amenable to quantitative analysis by computational fluid dynamics to extract intrinsic deposition rates and limiting reactant transport diffusivities, enabling predictive physics-based modeling of the deposition process. This allows the deposition method to be adapted for spin coating on silicon wafers to prepare high-quality aZIF films with consistently controlled thickness. Using this approach, high-resolution resist performance and wafer-scale use for beyond extreme-ultraviolet lithography of aZIF films is demonstrated.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Applying deep learning methods to develop new models of molecular charge transfer, nonadiabatic dynamics, and nonlinear spectroscopy in the condensed phase

Photon- and field-induced charge transfer has central importance in the generation and storage of electricity, the novel properties of materials, photo-induced catalysis, and electro-optic activity (e.g., photovoltaic cells, fuel cells, and organic chromophores for use in optical fibers and light-emission diodes). These non-equilibrium electronic and chemical transformations are probed by ultrafast, nonlinear spectroscopies. Accurate simulations play a crucial role in our ability to understand, optimize, and control these transformations. This project applies modern deep learning and machine learning (ML) methods to dramatically improve models of electronic dynamics, electronic-nuclear dynamics, and spectroscopic measurements for improved simulations of chemistry in complex environments, far from equilibrium phenomena, and processes in extreme environments, such as materials exposed to strong or resonant fields. This project develops accurate neural net models that go beyond predictive capability to also provide new insight into the fundamental physics underlying electron and nuclear dynamics. To achieve its objectives, this project explores and develops customized versions of high-capacity deep learning algorithms/models. These techniques are developed with an emphasis on fundamental chemical insight, not just predictive accuracy, to assist the development of the next generation of quantum simulation methods.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1979

The effect of energetically produced O2/+/ on the ion temperatures of the Martian thermosphere

The heating rates and ion temperatures of the Martian thermosphere resulting from the thermalization of the energetic O2(+) ions produced by the reactions of the solar ionization products CO2(+) and O(+) with neutral particles are calculated and the effects of small magnetic fields on the ion thermal balance are investigated. The energy transfer and transport of energetic ions is modelled by solving the continuity equation for the ions over a series of finite energy cells yielding the equilibrium densities as a function of energy and altitude. Particles which are able to proceed upwards without collisions are dealt with separately from the continuity equation. It is shown that the thermalization of the energetic O2(+) ions can greatly increase ion temperatures above 200 km compared to those calculated for only ambient electron heating. Current solar wind interaction models predict that small horizontal magnetic fields act to restrict the ion thermal conductivity and to increase upper altitude ion temperatures. The combined effects of these processes provide a partial agreement with measurements made by Viking 1.

Rohrbaugh, R. P.↗
DOE OSTI2021

Facet-specific oxidation of Mn(II) and heterogeneous growth of manganese (oxyhydr)oxides on hematite nanoparticles

It is recognized that different facets of minerals vary distinctively in their chemical reactivity with aqueous solutions. However, detailed molecular and atomistic understandings of these phenomena are relatively limited. This study investigated the interaction of aqueous Mn2+ and dissolved oxygen on various facets of two morphology-types of iron oxide (hematite) nanocrystals. These interactions result in the oxidation of manganese and the heterogeneous nucleation and growth of Mn(II)/Mn(III), and Mn(III) oxides. The nanoscale morphology and atomic structure of the manganese oxide products were characterized in detail. Our results, for the first time, directly demonstrate the facet-dependent oxidation of Mn 2+ and nucleation of Mn(II/III) oxides, followed by their epitaxial growth on hematite. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron diffraction measurements reveal the growth of MnOx nanowires on {012} facets of both hematite nanoplates (HNP) and hematite nanocubes (HNC), while the basal {001} facets on the HNP particles do not produce precipitates. The average oxidation state of the MnO x on HNP and HNC determined using electron energy-loss spectroscopy (EELS) show that both Mn(II) and Mn(III) are present. The facet-dependent oxidation of Mn 2+ may be attributed to adsorption-induced electron transfer (ET), and hematite {001} facets generally exhibiting weaker ability in the uptake of ions relative to {012} facets, and the bulk ET from {012} to {001} facets through the conduction band of hematite. Nevertheless, the mineral composition and growth mechanisms of MnOx catalyzed by HNP and HNC are similar. High-resolution TEM analysis reveals the presence of both hausmannite and manganite on HNP and HNC. The nanoscale observations and thermodynamic considerations indicate that the growth mechanisms/processes of MnO x include heterogeneous nucleation of hausmannite nanoparticles, crystallization by particle attachment, transformation from hausmannite to manganite, and self-catalyzed MnO x growth. It is possible that all of these processes are concurrent. The crystallographic relationship between the heterogeneously formed manganite with hematite, which has not been reported before, proves that hematite provides reaction sites and functions as an atomic template for the formation of MnO x nanowires. These findings advance our understanding of the redox chemistry and heterogeneous growth of minerals as controlled by the surficial structure of the substrate mineral. This has important geochemical implications as the catalytic growth of less common, highly reactive phases like MnO x are known to be consequential in complex natural and anthropogenic environments.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Excited-State Charge Transfer in Push–Pull Platinum(II) π-Extended Porphyrins Fused with Pentacenequinone

Platinum(II) π-extended porphyrins fused with pentacenequinone and dihydropentacene have been successfully synthesized. These porphyrins were investigated using various techniques including absorption, steady-state, and time-resolved phosphorescence spectroscopy and differential pulse voltammetry. UV–vis absorption spectra of pentacenequinone-fused porphyrins (SW-Pt1 and SW-Pt2) showed unusually broad and nontypical absorption patterns. Phosphorescence spectra of SW-Pt1, SW-Pt2, and SW-Pt3 displayed similar emissions in the 704–706 nm region indicating electronic transitions of similar origin; however, the triplet lifetimes were found to be quenched in the case of both SW-Pt1 and SW-Pt2, suggesting the occurrence of excited-state events. Facile reductions were obtained for both the pentacene-quinone-fused monomer (SW-Pt2) and dimer (SW-Pt1) and were identified to be located at the pentacenequinone components. Here, the observed orbital segregations for SW-Pt2 and SW-Pt1 from DFT calculations supported the possibility of charge transfer in these push–pull systems. Interestingly, the established energy level diagram revealed that the charge transfer from the triplet excited Pt porphyrin is thermodynamically an uphill process. Systematic studies involving both femtosecond and nanosecond transient absorption techniques revealed that the singlet excited Pt porphyrins undergo an intermediate charge transfer state prior to populating the triplet state, providing a plausible explanation for phosphorescence quenching. The lifetime of the intermediate charge transfer states was found to be 25.9 and 5.68 ps, respectively, for SW-Pt1 and SW-Pt2.

Charge transfer↗
DOE OSTI2024

Novel order-level lineage of ammonia-oxidizing archaea widespread in marine and terrestrial environments

Ammonia-oxidizing archaea (AOA) are among the most ubiquitous and abundant archaea on Earth, widely distributed in marine, terrestrial, and geothermal ecosystems. However, the genomic diversity, biogeography, and evolutionary process of AOA populations in subsurface environments are vastly understudied compared to those in marine and soil systems. Here, we report a novel AOA order Candidatus (Ca.) Nitrosomirales which forms a sister lineage to the thermophilic Ca. Nitrosocaldales. Metagenomic and 16S rRNA gene-read mapping demonstrates the abundant presence of Nitrosomirales AOA in various groundwater environments and their widespread distribution across a range of geothermal, terrestrial, and marine habitats. Terrestrial Nitrosomirales AOA show the genetic capacity of using formate as a source of reductant and using nitrate as an alternative electron acceptor. Nitrosomirales AOA appear to have acquired key metabolic genes and operons from other mesophilic populations via horizontal gene transfer, including genes encoding urease, nitrite reductase, and V-type ATPase. The additional metabolic versatility conferred by acquired functions may have facilitated their radiation into a variety of subsurface, marine, and soil environments. We also provide evidence that each of the four AOA orders spans both marine and terrestrial habitats, which suggests a more complex evolutionary history for major AOA lineages than previously proposed. Together, these findings establish a robust phylogenomic framework of AOA and provide new insights into the ecology and adaptation of this globally abundant functional guild.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Numerical Analysis and Flow Induced Vibration Studies in Pressurized Helium Gas Cooling Channels

Los Alamos National Laboratory (LANL) is working with NorthStar Medical Radioisotopes (NMR) on their efforts to produce Mo-99 from the irradiation of Mo-100 targets. The NMR target consists of an Inconel window that allows the electron beam to penetrate and irradiate a stack of Mo-100 discs. The irradiation process generates large amounts of heat and is cooled using pressurized helium gas flowing at 400 g/s. LANL provides both numerical analysis support and experimental support. Computational fluid dynamics (CFD) simulations for both 300 g/s and 400 g/s are performed on the NMR target to analyze the helium flow through the NMR system. The pressure drop, the mass flow rate through each of the disc and window channels and the force applied on the first disc are some of the quantities estimated using CFD. These results will be combined with Monte Carlo N-Particle (MCNP) estimates of heat flux into the system from the electron beam to perform conjugate heat transfer analysis (CHT). The experiments presented in this report focus on the effect of the flow induced vibrations from helium flowing through the coolant gaps between the discs. There is concern that the flow induced vibrations may lead to excessive mass loss of the enriched Mo-100 discs, and the goal would be to mitigate the mass loss. This work presents benchtop tests of flow through a subset of the target stack which involves high speed imaging and displacement measurements used to estimate disc vibration, as well as mass loss.

42 ENGINEERING↗
NASA NTRSDate not supplied

On the Importance of Laboratory Astrophysics and Astrochemistry and Interdisciplinary Research: Two Success Stories

Here we present two examples that demonstrate how cross-disciplinary research projects, where experimentalists, modelers and observers work together to answer science questions, allow expertise to be shared and misconceptions or missing key elements to be tackled by looking at the problem from different perspectives. They also show how, by working in unison, the group can accomplish more than the sum of its parts by combining results into a higher-level understanding of the chemical processes taking place. The first project is a collaborative study between experimentalists, modelers and observers to1) produce laboratory analogs of cosmic grains and planetary aerosols (Titan, Pluto...) from different gas mixtures in cold astrophysically relevant conditions (<200 K); and 2) characterize them with scanning electron microscopy and visible-to-far-infrared spectroscopy in order to assess the impact of the precursors on their growth structure and optical properties. We can then produce and study analogs that are representative of different formation stages or environments, and provide their complex refractive indices to the scientific community. We will show how, by using these experimental optical constants of more representative analogs in radiative transfer and reflectance spectra models, better interpretations of (exo)planetary atmosphere- and surface observations are possible. The second project is an interdisciplinary study of the formation of benzene clouds in the atmosphere of Saturn’s largest moon, Titan. We will show how combining Earth and Planetary Science laboratory expertise, modeling and observations has led to providing to the scientific community, for the first time, experimental vapor pressures for benzene at cold temperatures(<200K) relevant to Titan’s atmospheric conditions. These have been used in microphysical models instead of the higher temperature extrapolations used previously, allowing a better match to observations.

Ella Sciamma-o'Brien↗
DOE OSTI2021

Hydrolysis of Small Oxo/Hydroxo Molecules Containing High Oxidation State Actinides (Th, Pa, U, Np, Pu): A Computational Study

The energetics of hydrolysis reactions for high oxidation states of oxo/hydroxo monomeric actinide species (Th IV O 2 , Pa IV O 2 , U IV O 2 , Pa V O 2 (OH), U V O 2 (OH), U VI O 3 , Np VI O 3 , Np VII O 3 (OH), and Pu VII O 3 (OH)) were calculated at the CCSD(T) level. The first step is the formation of a Lewis acid/base adduct with H 2 O (hydration), followed by a proton transfer to form a dihydroxide molecule (hydrolysis); this process is repeated until all oxo groups are hydrolyzed. The physisorption (hydration) for each H 2 O addition was predicted to be exothermic, ca. -20 kcal/mol. The hydrolysis products are preferred energetically over the hydration products for the +IV and +V oxidation states. The compounds with An VI are a turning point in terms of favoring hydration over hydrolysis. For An VII O 3 (OH), hydration products are preferred, and only two waters can bind; the complete hydrolysis process is now endothermic, and the oxidation state for the An in An(OH) 7 is +VI with two OH groups each having one-half an electron. The natural bond order charges and the reaction energies provide insights into the nature of the hydrolysis/hydration processes. The actinide charges and bond ionicity generally decrease across the period. Here, the ionic character decreases as the oxidation state and coordination number increase so that covalency increases moving to the right in the actinide period.

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

Mutual spin-phonon driving effects and phonon eigenvector renormalization in nickel (II) oxide

The physics of mutual interaction of phonon quasiparticles with electronic spin degrees of freedom, leading to unusual transport phenomena of spin and heat, has been a subject of continuing interests for decades. Despite its pivotal role in transport processes, the effect of spin-phonon coupling on the phonon system, especially acoustic phonon properties, has so far been elusive. By means of inelastic neutron scattering and first-principles calculations, anomalous scattering spectral intensity from acoustic phonons was identified in the exemplary collinear antiferromagnetic nickel (II) oxide, unveiling strong spin-lattice correlations that renormalize the polarization of acoustic phonon. In particular, a clear magnetic scattering signature of the measured neutron scattering intensity from acoustic phonons is demonstrated by its momentum transfer and temperature dependences. The anomalous scattering intensity is successfully modeled with a modified magneto-vibrational scattering cross-section, suggesting the presence of spin precession driven by phonon. The renormalization of phonon eigenvector is indicated by the observed “geometry-forbidden” neutron scattering intensity from transverse acoustic phonon. Importantly, the eigenvector renormalization cannot be explained by magnetostriction but instead, it could result from the coupling between phonon and local magnetization of ions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗