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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 937 records · Page 52
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Enhanced cutoff energies for direct and rescattered strong-field photoelectron emission of plasmonic nanoparticles

Abstract The efficient generation, accurate detection, and detailed physical tracking of energetic electrons are of applied interest for high harmonics generation, electron-impact spectroscopy, and femtosecond time-resolved scanning tunneling microscopy. We here investigate the generation of photoelectrons (PEs) by exposing plasmonic nanostructures to intense laser pulses in the infrared (IR) spectral regime and analyze the sensitivity of PE spectra to competing elementary interactions for direct and rescattered photoemission pathways. Specifically, we measured and numerically simulated emitted PE momentum distributions from prototypical spherical gold nanoparticles (NPs) with diameters between 5 and 70 nm generated by short laser pulses with peak intensities of 8.0 × 10 12 and 1.2 × 10 13 W/cm 2 , demonstrating the shaping of PE spectra by the Coulomb repulsion between PEs, accumulating residual charges on the NP, and induced plasmonic electric fields. Compared to well-understood rescattering PE cutoff energies for strong-field photoemission from gaseous atomic targets (10× the ponderomotive energy), our measured and simulated PE spectra reveal a dramatic cutoff-energy increase of two orders of magnitude with a significantly higher contribution from direct photoemission. Our findings indicate that direct PEs reach up to 93 % of the rescattered electron cutoff energy, in contrast to 20 % for gaseous atoms, suggesting a novel scheme for the development of compact tunable tabletop electron sources.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Generation of fast photoelectrons in strong-field emission from metal nanoparticles

We investigated the generation and control of fast photoelectrons (PEs) by exposing plasmonic nanoparticles (NPs) to short infrared (IR) laser pulses with peak intensities between 10 12 and 3 × 10 13 W/cm 2 . Our measured and numerically simulated PE momentum distributions demonstrate the extent to which PE yields and cutoff energies are controlled by the NP size, material, and laser peak intensity. For strong-field photoemission from spherical silver, gold, and platinum NPs with diameters between 10 and 100 nm our results confirm and surpass extremely high PEs cutoff energies, up to several hundred times the incident laser-pulse ponderomotive energy, found recently for gold nanospheres [Saydanzad et al., Nanophotonics 12, 1931 (2023)]. As reported previously for dielectric NPs [Rupp et al., J. Mod. Opt. 64, 995 (2017)], at higher intensities the cutoff energies we deduce from measured and simulated PE spectra tend to converge to a metal-independent limit. We expect these characteristics of light-induced electron emission from prototypical plasmonic metallic nanospheres to promote the understanding of the electronic dynamics in more complex plasmonic nanostructures and the design of nanoscale light-controlled plasmonic electron sources for photoelectronic devices of applied interest.

electron source↗
DOE OSTI2021

New reference materials for trace-levels of actinide elements in plutonium

In this report two plutonium oxides were prepared as unique reference materials for measurement of actinide elements present as trace constituents. Each reference material unit is approximately 200 mg of PuO 2 powder in a quartz glass bottle. Characterized attributes of the oxides included mass fractions of plutonium, americium, neptunium, and uranium. Isotope-amount ratios were also determined for plutonium and uranium, but neptunium and americium were observed to be monoisotopic 237 Np and 241 Am. Measurements for characterization and verification of the attributes show that plutonium and trace actinides are homogeneous with the exception of limited heterogeneity for uranium, primarily observed for the 238 U isotope. Model purification ages calculated from measured americium and uranium attribute values are consistent with material histories and indicate that these impurities are predominantly due to the decay of plutonium isotopes.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

An Exact Algorithm for the Linear Tape Scheduling Problem

Magnetic tapes are often considered as an outdated storage technology, yet they are still used to store huge amounts of data. Their main interests are a large capacity and a low price per gigabyte, which come at the cost of a much larger file access time than on disks. With tapes, finding the right ordering of multiple file accesses is thus key to performance. Moving the reading head back and forth along a kilometer long tape has a non-negligible cost and unnecessary movements thus have to be avoided. However, the optimization of tape request ordering has rarely been studied in the scheduling literature, much less than I/O scheduling on disks. For instance, minimizing the average service time for several read requests on a linear tape remains an open question. Therefore, in this paper, we aim at improving the quality of service experienced by users of tape storage systems, and not only the peak performance of such systems. To this end, we propose a reasonable polynomial-time exact algorithm while this problem and simpler variants have been conjectured NP-hard. We also refine the proposed model by considering U-turn penalty costs accounting for inherent mechanical accelerations. Then, we propose a low-cost variant of our optimal algorithm by restricting the solution space, yet still yielding an accurate suboptimal solution. Finally, we compare our algorithms to existing solutions from the literature on logs of the mass storage management system of a major datacenter. This allows us to assess the quality of previous solutions and the improvement achieved by our low-cost algorithm. Aiming for reproducibility, we make available the complete implementation of the algorithms used in our evaluation, alongside the dataset of tape requests that is, to the best of our knowledge, the first of its kind to be publicly released.

Honoré, Valentin↗
DOE OSTI2026

Plutonium Retention by Crystalline Silicotitanate under Hyperalkaline Conditions Relevant to Tank-Side Cesium-Removal at the Hanford Site

Crystalline silicotitanate (CST) is used in Hanford’s Tank-Side Cesium-Removal (TSCR) process to selectively remove Cs-137 from highly caustic, nitrate-rich tank supernatants. Recent testing with actual waste samples suggests that CST can also retain measurable plutonium (Pu), which could affect radiological classification and disposal pathways for spent CST. To quantify this behavior, Pu partitioning to CST was studied under Hanford-relevant conditions using batch-contact experiments in a representative simulant (2 M NaNO3, 0.7 M NaOH). Isotherm data were measured and distribution ratios calculated, with Cs+ uptake used as benchmark. Under low-carbonate conditions, Pu was retained strongly by CST in systems initially contacted with either PuO2 nanoparticles (Pu(IV)) or aqueous Pu(VI), with distribution ratios of ~2,200–3,700 mL/g, generally exceeding those for Cs+ (~400–1,000 mL/g). Increasing carbonate concentration strongly reduced PuO2 nanoparticle retention; at [Na2CO3] = 1 M, distribution ratios decreased by up to one order of magnitude to roughly 100–300 mL/g. Electron microscopy suggests that Pu retention involves a combination of mechanisms such as PuO2 NP aggregation induced by CST leachate components, and association with CST bead surfaces.

Neumann, J.↗
DOE OSTI2020

Materials Data on TeF6 by Materials Project

TeF6 is beta Np structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four TeF6 clusters. Te6+ is bonded in an octahedral geometry to six F1- atoms. There is two shorter (1.86 Å) and four longer (1.87 Å) Te–F bond length. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Te6+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Te6+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Te6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on OsF6 by Materials Project

OsF6 is beta Np structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four osmium hexafluoride molecules. Os6+ is bonded in an octahedral geometry to six F1- atoms. All Os–F bond lengths are 1.87 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Os6+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Os6+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Os6+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one Os6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UF6 by Materials Project

UF6 is beta Np structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four uranium hexafluoride molecules. U6+ is bonded in an octahedral geometry to six F1- atoms. There are five shorter (2.02 Å) and one longer (2.03 Å) U–F bond lengths. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one U6+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one U6+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one U6+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one U6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PCl5 by Materials Project

PCl5 is beta Np structured and crystallizes in the tetragonal P4/n space group. The structure is zero-dimensional and consists of two [pcl4]+1 molecules and two PCl6 clusters. In each PCl6 cluster, P5+ is bonded in an octahedral geometry to six Cl1- atoms. There are a spread of P–Cl bond distances ranging from 2.16–2.20 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one P5+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one P5+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AsCl2F3 by Materials Project

AsCl4AsF6 is beta Np structured and crystallizes in the tetragonal P4/n space group. The structure is zero-dimensional and consists of two AsCl4 clusters and two AsF6 clusters. In each AsCl4 cluster, As5+ is bonded in a tetrahedral geometry to four equivalent Cl1- atoms. All As–Cl bond lengths are 2.10 Å. Cl1- is bonded in a distorted single-bond geometry to one As5+ atom. In each AsF6 cluster, As5+ is bonded in an octahedral geometry to six F1- atoms. There are a spread of As–F bond distances ranging from 1.76–1.79 Å. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on As4S3 by Materials Project

As4S3 is beta Np structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four tetraarsenic trisulfide molecules. there are three inequivalent As+1.50+ sites. In the first As+1.50+ site, As+1.50+ is bonded in a single-bond geometry to one S2- atom. The As–S bond length is 2.24 Å. In the second As+1.50+ site, As+1.50+ is bonded in a single-bond geometry to one S2- atom. The As–S bond length is 2.23 Å. In the third As+1.50+ site, As+1.50+ is bonded in a distorted trigonal non-coplanar geometry to three S2- atoms. All As–S bond lengths are 2.27 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a water-like geometry to two As+1.50+ atoms. In the second S2- site, S2- is bonded in a water-like geometry to two As+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on P4SO6 by Materials Project

P4SO6 is beta Np structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four P4SO6 clusters. there are four inequivalent P+3.50+ sites. In the first P+3.50+ site, P+3.50+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There are a spread of P–O bond distances ranging from 1.66–1.69 Å. In the second P+3.50+ site, P+3.50+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.66 Å) and one longer (1.69 Å) P–O bond length. In the third P+3.50+ site, P+3.50+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There are a spread of P–O bond distances ranging from 1.66–1.69 Å. In the fourth P+3.50+ site, P+3.50+ is bonded in a distorted tetrahedral geometry to one S2- and three O2- atoms. The P–S bond length is 1.90 Å. All P–O bond lengths are 1.62 Å. S2- is bonded in a single-bond geometry to one P+3.50+ atom. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two P+3.50+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two P+3.50+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two P+3.50+ atoms. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+3.50+ atoms. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+3.50+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CBr3F by Materials Project

CFBr3 is beta Np structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four tribromofluoromethane molecules. C4+ is bonded in a distorted tetrahedral geometry to three Br1- and one F1- atom. There is two shorter (1.95 Å) and one longer (1.96 Å) C–Br bond length. The C–F bond length is 1.36 Å. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a single-bond geometry to one C4+ atom. In the second Br1- site, Br1- is bonded in a distorted single-bond geometry to one C4+ atom. F1- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on P4(SO2)3 by Materials Project

P4(SO2)3 is beta Np structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four P4(SO2)3 clusters. there are four inequivalent P+4.50+ sites. In the first P+4.50+ site, P+4.50+ is bonded to one S2- and three O2- atoms to form distorted corner-sharing PSO3 tetrahedra. The P–S bond length is 1.88 Å. There is one shorter (1.62 Å) and two longer (1.64 Å) P–O bond length. In the second P+4.50+ site, P+4.50+ is bonded to one S2- and three O2- atoms to form distorted corner-sharing PSO3 tetrahedra. The P–S bond length is 1.88 Å. There is one shorter (1.62 Å) and two longer (1.64 Å) P–O bond length. In the third P+4.50+ site, P+4.50+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. All P–O bond lengths are 1.68 Å. In the fourth P+4.50+ site, P+4.50+ is bonded to one S2- and three O2- atoms to form distorted corner-sharing PSO3 tetrahedra. The P–S bond length is 1.88 Å. There is one shorter (1.62 Å) and two longer (1.64 Å) P–O bond length. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a single-bond geometry to one P+4.50+ atom. In the second S2- site, S2- is bonded in a single-bond geometry to one P+4.50+ atom. In the third S2- site, S2- is bonded in a single-bond geometry to one P+4.50+ atom. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SiI3 by Materials Project

SiI3 is beta Np structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four hexaiododisilane molecules. there are two inequivalent Si sites. In the first Si site, Si is bonded in a distorted tetrahedral geometry to one Si and three I atoms. The Si–Si bond length is 2.37 Å. All Si–I bond lengths are 2.46 Å. In the second Si site, Si is bonded in a distorted tetrahedral geometry to one Si and three I atoms. All Si–I bond lengths are 2.46 Å. There are four inequivalent I sites. In the first I site, I is bonded in a single-bond geometry to one Si atom. In the second I site, I is bonded in a single-bond geometry to one Si atom. In the third I site, I is bonded in a single-bond geometry to one Si atom. In the fourth I site, I is bonded in a single-bond geometry to one Si atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si2H6Se by Materials Project

Si2H6Se is alpha Np structured and crystallizes in the tetragonal P4_32_12 space group. The structure is zero-dimensional and consists of eight disilaselenane molecules. there are two inequivalent Si sites. In the first Si site, Si is bonded to three H+0.33+ and one Se2- atom to form corner-sharing SiH3Se tetrahedra. All Si–H bond lengths are 1.49 Å. The Si–Se bond length is 2.31 Å. In the second Si site, Si is bonded to three H+0.33+ and one Se2- atom to form corner-sharing SiH3Se tetrahedra. All Si–H bond lengths are 1.49 Å. The Si–Se bond length is 2.31 Å. There are six inequivalent H+0.33+ sites. In the first H+0.33+ site, H+0.33+ is bonded in a single-bond geometry to one Si atom. In the second H+0.33+ site, H+0.33+ is bonded in a single-bond geometry to one Si atom. In the third H+0.33+ site, H+0.33+ is bonded in a single-bond geometry to one Si atom. In the fourth H+0.33+ site, H+0.33+ is bonded in a single-bond geometry to one Si atom. In the fifth H+0.33+ site, H+0.33+ is bonded in a single-bond geometry to one Si atom. In the sixth H+0.33+ site, H+0.33+ is bonded in a single-bond geometry to one Si atom. Se2- is bonded in an L-shaped geometry to two Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on P4(SeO2)3 by Materials Project

P4(SeO2)3 is beta Np structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four P4(SeO2)3 clusters. there are four inequivalent P+4.50+ sites. In the first P+4.50+ site, P+4.50+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. All P–O bond lengths are 1.68 Å. In the second P+4.50+ site, P+4.50+ is bonded to one Se2- and three O2- atoms to form distorted corner-sharing PSeO3 tetrahedra. The P–Se bond length is 2.04 Å. There is one shorter (1.62 Å) and two longer (1.64 Å) P–O bond length. In the third P+4.50+ site, P+4.50+ is bonded to one Se2- and three O2- atoms to form distorted corner-sharing PSeO3 tetrahedra. The P–Se bond length is 2.03 Å. There are a spread of P–O bond distances ranging from 1.62–1.65 Å. In the fourth P+4.50+ site, P+4.50+ is bonded to one Se2- and three O2- atoms to form distorted corner-sharing PSeO3 tetrahedra. The P–Se bond length is 2.04 Å. There is one shorter (1.62 Å) and two longer (1.64 Å) P–O bond length. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted single-bond geometry to one P+4.50+ atom. In the second Se2- site, Se2- is bonded in a distorted single-bond geometry to one P+4.50+ atom. In the third Se2- site, Se2- is bonded in a single-bond geometry to one P+4.50+ atom. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi7RhBr8 by Materials Project

RhBi7Br8 is beta Np structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four RhBi7Br8 clusters. Rh is bonded in a pentagonal bipyramidal geometry to seven Bi atoms. There are a spread of Rh–Bi bond distances ranging from 2.73–2.76 Å. There are seven inequivalent Bi sites. In the first Bi site, Bi is bonded in a distorted T-shaped geometry to one Rh and two Br atoms. There are one shorter (2.93 Å) and one longer (3.05 Å) Bi–Br bond lengths. In the second Bi site, Bi is bonded to one Rh and four Br atoms to form corner-sharing BiRhBr4 square pyramids. There are a spread of Bi–Br bond distances ranging from 2.87–3.11 Å. In the third Bi site, Bi is bonded to one Rh and four Br atoms to form corner-sharing BiRhBr4 square pyramids. There are a spread of Bi–Br bond distances ranging from 2.88–3.10 Å. In the fourth Bi site, Bi is bonded in a distorted water-like geometry to one Rh and one Br atom. The Bi–Br bond length is 2.79 Å. In the fifth Bi site, Bi is bonded in a distorted water-like geometry to one Rh and one Br atom. The Bi–Br bond length is 2.80 Å. In the sixth Bi site, Bi is bonded in a distorted T-shaped geometry to one Rh and two Br atoms. There are one shorter (2.85 Å) and one longer (3.15 Å) Bi–Br bond lengths. In the seventh Bi site, Bi is bonded in a distorted T-shaped geometry to one Rh and two Br atoms. There are one shorter (2.91 Å) and one longer (3.02 Å) Bi–Br bond lengths. There are eight inequivalent Br sites. In the first Br site, Br is bonded in an L-shaped geometry to two Bi atoms. In the second Br site, Br is bonded in an L-shaped geometry to two Bi atoms. In the third Br site, Br is bonded in an L-shaped geometry to two Bi atoms. In the fourth Br site, Br is bonded in an L-shaped geometry to two Bi atoms. In the fifth Br site, Br is bonded in an L-shaped geometry to two Bi atoms. In the sixth Br site, Br is bonded in an L-shaped geometry to two Bi atoms. In the seventh Br site, Br is bonded in an L-shaped geometry to two Bi atoms. In the eighth Br site, Br is bonded in a distorted L-shaped geometry to two Bi atoms.

36 MATERIALS SCIENCE↗