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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Single-pixel reconstructive mid-infrared micro-spectrometer

Miniaturized spectrometers in the mid-infrared (MIR) are critical in developing next-generation portable electronics for advanced sensing and analysis. The bulky gratings or detector/filter arrays in conventional micro-spectrometers set a physical limitation to their miniaturization. In this work, we demonstrate a single-pixel MIR micro-spectrometer that reconstructs the sample transmission spectrum by a spectrally dispersed light source instead of spatially grated light beams. The spectrally tunable MIR light source is realized based on the thermal emissivity engineered via the metal-insulator phase transition of vanadium dioxide (VO 2 ). We validate the performance by showing that the transmission spectrum of a magnesium fluoride (MgF 2 ) sample can be computationally reconstructed from sensor responses at varied light source temperatures. With potentially minimum footprint due to the array-free design, our work opens the possibility where compact MIR spectrometers are integrated into portable electronic systems for versatile applications.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Encapsulation and retention of 225 Ac, 223 Ra, 227 Th, and decay daughters in zircon-type gadolinium vanadate nanoparticles

Abstract Unwanted targeting of healthy organs caused by the relocation of radionuclides from the target site has been one of the limiting factors in the widespread application of targeted alpha therapy in patient regimens. GdVO 4 nanoparticles (NPs) were developed as platforms to encapsulate α -emitting radionuclides 223 Ra, 225 Ac, and 227 Th, and retain their decay daughters at the target site. Polycrystalline GdVO 4 NPs with different morphologies and a zircon-type tetragonal crystal structure were obtained by precipitation of GdCl 3 and Na 3 VO 4 in aqueous media at room temperature. The ability of GdVO 4 crystals to host multivalent ions was initially assessed using La, Cs, Bi, Ba, and Pb as surrogates of the radionuclides under investigation. A decrease in Ba encapsulation was obtained after increasing the concentration of surrogate ions, whereas the encapsulation of La cations in GdVO 4 NPs was quantitative (∼100%). Retention of radionuclides was assessed in vitro by dialyzing the radioactive GdVO 4 NPs against deionized water. While 227 Th was quantitatively encapsulated (100%), a partial encapsulation of 223 Ra (∼75%) and 225 Ac (>60%) was observed in GdVO 4 NPs. The maximum leakage of 221 Fr (1st decay daughter of 225 Ac) was 55.4 ± 3.6%, whereas for 223 Ra (1st decay daughter of 227 Th) the maximum leakage was 73.0 ± 4.0%. These results show the potential of GdVO 4 NPs as platforms of α -emitting radionuclides for their application in targeted alpha therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2020

Materials Data on VP2O7 by Materials Project

VO(PO3)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. V4+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of V–O bond distances ranging from 1.63–2.01 Å. P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one V4+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to one V4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent P5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on VP2O7 by Materials Project

VO(PO3)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. V4+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one VO6 octahedra. There are a spread of V–O bond distances ranging from 1.88–2.11 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 33–56°. There are a spread of P–O bond distances ranging from 1.47–1.63 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 34–46°. There are a spread of P–O bond distances ranging from 1.53–1.58 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent V4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V4+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2V2P4O15 by Materials Project

K2(VO)2P4O13 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of K–O bond distances ranging from 2.78–3.39 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.72–3.40 Å. There are two inequivalent V4+ sites. In the first V4+ site, V4+ is bonded to six O2- atoms to form distorted VO6 octahedra that share corners with five PO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.65–2.26 Å. In the second V4+ site, V4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of V–O bond distances ranging from 1.63–2.33 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. There are a spread of P–O bond distances ranging from 1.49–1.60 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–44°. There are a spread of P–O bond distances ranging from 1.51–1.65 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.60 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. There are a spread of P–O bond distances ranging from 1.52–1.65 Å. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one K1+ and two P5+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two K1+, one V4+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two K1+, one V4+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one V4+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one V4+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one V4+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent K1+, one V4+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one V4+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one V4+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V4+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted single-bond geometry to two K1+, one V4+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to one K1+ and one V4+ atom. In the fourteenth O2- site, O2- is bonded in a 2-coordinate geometry to two K1+, one V4+, and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V2P2O9 by Materials Project

(VO)2P2O7 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. V4+ is bonded to six O2- atoms to form distorted VO6 octahedra that share corners with two equivalent VO6 octahedra, corners with four equivalent PO4 tetrahedra, and an edgeedge with one VO6 octahedra. The corner-sharing octahedral tilt angles are 16°. There are a spread of V–O bond distances ranging from 1.68–2.14 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four equivalent VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 30–51°. There are a spread of P–O bond distances ranging from 1.51–1.59 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V4+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to two equivalent V4+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent V4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V2P2O9 by Materials Project

(VO)2P2O7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent V4+ sites. In the first V4+ site, V4+ is bonded to six O2- atoms to form VO6 octahedra that share corners with two equivalent VO6 octahedra, corners with three equivalent PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of V–O bond distances ranging from 1.90–2.07 Å. In the second V4+ site, V4+ is bonded to six O2- atoms to form VO6 octahedra that share corners with two equivalent VO6 octahedra, corners with four PO4 tetrahedra, and edges with two equivalent VO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of V–O bond distances ranging from 1.88–2.05 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with five VO6 octahedra. The corner-sharing octahedra tilt angles range from 1–53°. There are a spread of P–O bond distances ranging from 1.52–1.60 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and an edgeedge with one VO6 octahedra. The corner-sharing octahedral tilt angles are 44°. There are a spread of P–O bond distances ranging from 1.53–1.57 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in an L-shaped geometry to one V4+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the third O2- site, O2- is bonded in a linear geometry to one V4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in an L-shaped geometry to one V4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent V4+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three V4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Develop On-Demand nanoplasmonic Device Concepts in a Semiconductor Compatible Hybrid System. Final Report

This report summarizes the research activities supported by the U.S. Department of Energy grant DE-SC-0010399. The goal of this project is to is to develop an on-demand nanoplasmonic platform that combines emerging oxide nanoelectronics with a low-loss semiconductor-friendly plasmonic materials. Toward this goal, several unique heterostructures formed between complex oxides and 2D layered materials have been developed. Based on these material systems, a set of atomic force microscope (AFM) based techniques have been developed that can allow long-living and reversible material phase transitions to be manipulated in nanoscale at room temperature. Using such technique and through interface coupling, we can effectively tune the plasmon propagations in unconventional plasmonic materials such as graphene and VO 2 . In addition, we also discovered a plethora of novel interface enabled electro-optic effects, including the spatial modulation of light using 2DEG, a giant programmable photothermoelectric effects at room temperature, a light induced superconducting transition, and a tunable giant third order optical nonlinearities. These major results are outlined in this report, along with lists of project participants and products.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

How Snow Drives the Seasonal Evolution of Land and Sea Surface Albedos in the Alaskan High Arctic: Final Technical Report

The purpose of the project was to observe and quantify temporal variation in snow albedo and snow characteristics across the Arctic coastal landscape as winter transitioned into spring and snowmelt occurred, both on tundra and sea ice. This transition is bounded by fully snow-covered landscapes with broadband albedos of approximately 0.8 and snow-free landscapes with albedos of 0.15 (tundra or ponded sea ice). For these landscapes, we monitored the spring surface characteristics and radiative properties nearly daily at three locations on or near the Department of Energy ARM North Slope of Alaska (NSA) User Facility in Utqiagvik, Alaska: the central NSA Facility (hereafter called ARM), one near NSA-E12 (BEO), and one on the sea ice of Elson Lagoon (ICE) during three melt seasons (2019, 2022, and 2024). The field campaign component of this award was named SALVO ( S now AL bedo E VO lution). Typical field seasons began in mid-April and lasted until mid-June. Main measurements included snow depth (at 1-m intervals), broadband albedo (at 5-m intervals), spectral albedo (at 5- m intervals), and multiple digital images. Orthomosaics were converted into binary images to determine the snow-covered fraction over time across various landscapes. Additional measurements included basic weather data and snow-ground (or ice) interface temperatures. Sky conditions were observed and photographed to help assess albedo values.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

A Smart System for the Contactless Measurement of Energy Expenditure

Energy Expenditure (EE) (kcal/day), a key element to guide obesity treatment, is measured from CO 2 production, VCO 2 (mL/min), and/or O 2 consumption, VO 2 (mL/min). Current technologies are limited due to the requirement of wearable facial accessories. A novel system, the Smart Pad, which measures EE via VCO 2 from a room’s ambient CO 2 concentration transients was evaluated. Resting EE (REE) and exercise VCO 2 measurements were recorded using Smart Pad and a reference instrument to study measurement duration’s influence on accuracy. The Smart Pad displayed 90% accuracy (±1 SD) for 14–19 min of REE measurement and for 4.8–7.0 min of exercise, using known room’s air exchange rate. Additionally, the Smart Pad was validated measuring subjects with a wide range of body mass indexes (BMI = 18.8 to 31.4 kg/m2), successfully validating the system accuracy across REE’s measures of ~1200 to ~3000 kcal/day. Furthermore, high correlation between subjects’ VCO 2 and λ for CO 2 accumulation was observed (p < 0.00001, R = 0.785) in a 14.0 m3 sized room. This finding led to development of a new model for REE measurement from ambient CO 2 without λ calibration using a reference instrument. The model correlated in nearly 100% agreement with reference instrument measures (y = 1.06x, R = 0.937) using an independent dataset (N = 56).

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

ARES I: WASP-76 b, A Tale of Two HST Spectra

We analyze the transmission and emission spectra of the ultra-hot Jupiter WASP-76 b, observed with the G141 grism of the Hubble Space Telescope’s (HST) Wide Field Camera 3 (WFC3). We reduce and fit the raw data for each observation using the open-source software Iraclis before performing a fully Bayesian retrieval using the publicly available analysis suite TauREx 3. Previous studies of the WFC3 transmission spectra of WASP-76 b found hints of titanium oxide (TiO) and vanadium oxide (VO) or non-gray clouds. Accounting for a fainter stellar companion to WASP-76, we reanalyze this data and show that removing the effects of this background star changes the slope of the spectrum, resulting in these visible absorbers no longer being detected, eliminating the need for a non-gray cloud model to adequately fit the data but maintaining the strong water feature previously seen. However, our analysis of the emission spectrum suggests the presence of TiO and an atmospheric thermal inversion, along with a significant amount of water. Given the brightness of the host star and the size of the atmospheric features, WASP-76 b is an excellent target for further characterization with HST, or with future facilities, to better understand the nature of its atmosphere, to confirm the presence of TiO and to search for other optical absorbers.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

TESS Observations of the WASP-121 b Phase Curve

We study the red-optical photometry of the ultrahot Jupiter WASP-121 b as observed by the Transiting Exoplanet Survey Satellite (TESS) and model its atmosphere through a radiative transfer simulation. Given its short orbital period of ∼1.275 days, inflated state, and bright host star, WASP-121 b is exceptionally favorable for detailed atmospheric characterization. Toward this purpose, we use allesfitter to characterize its full red-optical phase curve, including the planetary phase modulation and secondary eclipse. We measure the day- and nightside brightness temperatures in the TESS passband as 3012{sub −42}{sup +40} and 2022{sub −602}{sup +254} K, respectively, and do not find a statistically significant phase shift between the brightest and substellar points. This is consistent with inefficient heat recirculation on the planet. We then perform an atmospheric retrieval analysis to infer the dayside atmospheric properties of WASP-121 b, such as its bulk composition, albedo, and heat recirculation. We confirm the temperature inversion in the atmosphere and suggest H{sup −}, TiO, and VO as potential causes of the inversion, absorbing heat at optical wavelengths at low pressures. Future Hubble Space Telescope and James Webb Space Telescope observations of WASP-121 b will benefit from its first full phase curve measured by TESS.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1973

Temperature, illumination and fluence dependence of current and voltage in electron irradiated solar cells

Emperical equations have been derived from measurements of solar cell photovoltaic characteristics relating light generated current, IL, and open circuit voltage, VO, to cell temperature, T, intensity of illumination, W, and 1 Mev electron fluence, phi both 2 ohm-cm and 10 ohm-cm cells were tested. The temperature dependency of IL is similar for both resistivities at 140mw/sq cm; at high temperature the coefficient varies with fluence as phi 0.18, while at low temperatures the coefficient is relatively independent of fluence. Fluence dependent degration causes a decrease in IL at a rate proportional to phi 0.153 for both resistivities. At all intensities other than 560 mw/sq cm, a linear dependence of IL on illumination was found. The temperature coefficient of voltage was, to a good approximation, independent of both temperature and illumination for both resistivities. Illumination dependence of VOC was logarithmic, while the decrease with fluence of VOC varied as phi 0.25 for both resistivities.

Obenschain, A. F.↗
NASA NTRS1975

Summary report on the Viking 1975 DSN telecommunications compatibility test program

The system design tests and test results that provided the basis for establishment of telecommunications design between the DSN and Viking 1975 were described. The Viking 1975/DSN Telecommunications Compatibility Test Program Consisted of three phases: subsystem design, system design, and system verification tests which were performed at JPL and at the Air Force Eastern Test Range and Kennedy Space Center complexes. Subsystem design tests were performed with the Viking Orbiter (VO) and the Viking Lander (VL) during 1973. System design compatibility tests were performed with the Viking Proof Test Orbiter, Viking Spacecraft Test Lander, and a multiple Viking spacecraft configuration during the summer of 1974. System verification tests were performed with the Viking Orbiter, Viking Lander and Viking spacecraft during the spring and summer of 1975.

A. I. Bryan↗
NASA NTRS1978

Deep Space Network to Viking Orbiter telecommunications performance during the Viking extended mission, November 1976 - February 1978

The telecommunications performance during the Viking extended mission, starting with the completion of the first superior conjunction in November 1976 and ending with the jettison of the VO-2 aft bioshield early in March 1978 is discussed. Viking Orbiter activities and problems, the ground system activities and problems, radio science activities, and communication link performance are included. The substantial involvement of the Deep Space Network and the coordination of their telecommunication planners with Viking Project telecommunications analysts in the planning and execution of complex Viking Orbiter sequences are discussed.

Taylor, F. H. J.↗
NASA NTRS1981

Studies of bipolar nebulae. VII - The exciting star of OH 0739-14 /equals OH 231.8 plus 4.2/

A spectral classification for the exciting star of the bipolar reflection nebula OH 0739-14, which has also been observed to be an OH/H2O maser source, is obtained from the spectrum of the nebulosity in the range 6000-9000 A. Spectrophotometry of the visible nebula was obtained with the Cassegrain image-tube scanner on the Lick Observatory 3-m telescope at a resolution of approximately 7 A. The red spectrum is found to be distinguished by TiO absorption at the bandheads at 8206, 8303, 8432, 8442 and 8452 A and VO in the 7400 and 7900 A regions. On the basis of the depths of these bandheads and the K I 7699 A and Ca II infrared triplet, OH 0739-14 is determined to be of spectral type M9 III. The underlying star thus represents the coolest known star to occur in a bipolar system.

Cohen, M.↗
NASA NTRS1981

A spectroscopic, photometric, and magnetic study of the starspot on II Pegasi

A description is presented of extensive observations of II Peg during 1977 and 1978, taking into account multicolor broad-band photometry, high-dispersion spectroscopy, low-dispersion spectrophotometry, and Zeeman analysis. During this time the star showed periodic light variations in excess of a 0.4 mag range attributable to the presence of a large starspot or an equivalent nonuniform surface brightness distribution. The high-precision multicolor photometry, which differed greatly from previous photometric results, illustrates that the starspots on II Peg are continually evolving on time scales of approximately 1 year or less. A low-dispersion spectrum of the large spot showed pronounced VO and TiO molecular adsorption features. A high-resolution, high signal-to-noise Reticon spectrum at lambda 6707 does not show any compelling evidence of previously reported lithium in this star.

Vogt, S. S.↗