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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Observation of fullerenes (C60-C70) associated with LDEF crater number 31

The presence of fullerenes in and around the LDEF crater number 31 is reported. This crater has a high C level associated with it, and is interpreted as having been produced by the impact of a C-rich micrometeoroid. Fullerenes are large 3-D C structures, among which the species C sub 60 (MW 720) and C sub 70 (MW 840) are preeminent. Fullerenes have several UV absorption bands, hence fullerenes should be detectable using UV laser ionization time-of-flight mass spectrometry. We use a LIMA-2A instrument with pulsed UV laser (266 nm) to search for high mass C species associated with LDEF crater number 31. The mass range was 0 to 1200 amu. Low ablating laser power levels were used (less than or = 5 x 10 exp 7 W/sq. cm); 200 mass spectra were acquired and summed. We observed high mass signals near m/z 720, exhibiting 24 amu separation, which is characteristic of fullerenes. Alkali ion signals were also observed. Little or no C clusters of intermediate mass were observed. We interpret the signals around m/z 720 as fullerenes, mainly C sub 60+ with lower levels of C sub 70+. We propose that the mechanism that produces these signals is resonant multiphoton ionization (REMPI). This selective mechanism explains why low mass C cluster ions are not observed along with the fullerenes, since they have much higher ionization potentials. This finding is unexpected, since up to now the search for fullerenes in extraterrestrial materials has not been successful. We conclude that the fullerenes became associated with crater number 31 in space. Two alternative (and exciting) scenarios are being considered at this time: either the fullerenes were carried by the C-rich projectile that formed crater number 31, or the fullerenes formed upon impact with the LDEF. We show the results of experiments at the ARC Vertical Gun Facility, which may establish some constraints on the origin of the fullerenes.

Radicatidibrozolo, Filippo↗
DOE OSTI2011

Isotopic effects in the energy spectrum of molecules sputtered from carbon

We investigate the translational and rovibrational energy spectra of sputtered molecules resulting from bombardment of hydrogen-supersaturated carbon by hydrogen isotopes H, D, and T at energies of 1-20 eV using classical molecular dynamics simulations. The chemical erosion yields and mass spectra of sputtered molecules are found to be quite sensitive to the isotope mass of the impinging projectiles. However, the mean translational and rovibrational energies of the sputtered molecules are found to be nearly mass independent especially near the sputtering thresholds.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1974

Time-dependent outgassing and impurities in the NASA Lewis Bumpy Torus

In the investigation about 1000 mass spectra were taken with the aid of a quadrupole mass filter. Attention was given to the determination of the densities of impurities as functions of time during operation. Studies of (almost) steady-state spectra were conducted. Analyses of the gas released when cold surfaces were allowed to warm up were also carried out. The results of the investigation suggest that the outgassing is diffusion-controlled.

Persson, H.↗
NASA NTRS2022

The Co2 Profile and Analytical Model for the Pioneer Venus Large Probe Neutral Mass Spectrometer

We present a significantly updated CO2 altitude profile for Venus (64.2–0.9 km) and provide support for a potential deep lower atmospheric haze of particles (≤17 km). We extracted this information by developing a new analytical model for mass spectra obtained by the Pioneer Venus Large Probe (PVLP) Neutral Mass Spectrometer (LNMS). Our model accounts for changes in LNMS configuration and output during descent and enables the disentanglement of isobaric species via a data fitting routine that adjusts for mass-dependent changes in peak shape. The model yields CO2 in units of density (kg m−3), isotope ratios for 13C/12C and 18O/16O, and 14 measures of CO2 density across 55.4–0.9 km, which represents the most complete altitude profile for CO2 at ≤60 km to date. The CO2 density profile is also consistent with the pressure, temperature, and volumetric gas measurements from the PVLP and VeNeRa spacecraft. Nominal and low-noise operations for the LNMS mass analyzer are supported by the behaviors (e.g., ionization yields, fragmentation yields, and peak shapes) of several internal standards (e.g., CH3+, CH4+, 40Ar+, 136Xe2+, and 136Xe+), which were tracked across the descent. Lastly, our review of the CO2 profile and LNMS spectra reveals hitherto unreported partial and rapidly clearing clogs of the inlet in the lower atmosphere, along with several ensuing data spikes at multiple masses. Together, these observations suggest that atmospheric intake was impacted by particles at ≤17 km and that rapid particle degradation at the inlet yielded a temporary influx of mass signals into the LNMS.

Venus↗
DOE OSTI2024

Direct Experimental Observation of the Tetrabromine Cluster Br 4 by Synchrotron Photoionization Mass Spectrometry

We present a first spectroscopic characterization of the homoatomic polyhalogen tetrabromine, Br 4 , in the gas phase. Photolysis of CHBr 3 at 248 nm is used to generate atomic bromine radicals in a flow tube reactor. Resulting combination products are detected by photoionization mass spectrometry at the Advanced Light Source of the Lawrence Berkeley National Laboratory. Interpretation of the experimental mass spectra is informed by calculated adiabatic ionization energies carried out at the CCSD(T)/aug-cc-pVTZ//M06-2X/aug-cc-pVTZ and CCSD(T)/aug-cc-pVTZ//cam-B3LYP/6-311++g** levels of theory. Tunable VUV synchrotron radiation enables the collection of the mass-selected photoionization spectra by which Br 4 is assigned using Franck-Condon simulations of a Br 2 dimer with a stretched tetrahedral geometry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Native Mass Spectrometry Characterization of Intact Nanodisc Lipoprotein Complexes

We describe here the analysis of nanodisc complexes by using native mass spectrometry (MS) to characterize their molecular weight (MW) and polydispersity. Nanodiscs are nanoscale lipid bilayers that offer a platform for solubilizing membrane proteins. Unlike detergent micelles, nanodiscs are native-like lipid bilayers that are well-defined and potentially monodisperse. Their mass spectra allow peak assignment based on differences in the mass of a single lipid per complex. Resultant masses agree closely with predicted values and demonstrate conclusively the narrow dispersity of lipid molecules in the nanodisc. Fragmentation with collisionally activated dissociation (CAD) or electron-capture dissociation (ECD) shows loss of a small number of lipids and eventual collapse of the nanodisc with release of the scaffold protein. These results provide a foundation for future studies utilizing nanodiscs as a platform for launching membrane proteins into the gas phase.

14 SOLAR ENERGY↗
DOE OSTI2017

Influence of urban pollution on the production of organic particulate matter from isoprene epoxydiols in central Amazonia

The atmospheric chemistry of isoprene contributes to the production of a substantial mass fraction of the particulate matter (PM) over tropical forests. Isoprene epoxydiols (IEPOX) produced in the gas phase by the oxidation of isoprene under HO 2 -dominant conditions are subsequently taken up by particles, thereby leading to production of secondary organic PM. The present study investigates possible perturbations to this pathway by urban pollution. The measurement site in central Amazonia was located 4 to 6 h downwind of Manaus, Brazil. Measurements took place from February through March 2014 of the wet season, as part of the GoAmazon2014/5 experiment. Mass spectra of organic PM collected with an Aerodyne Aerosol Mass Spectrometer were analyzed by positive-matrix factorization. One resolved statistical factor ("IEPOX-SOA factor") was associated with PM production by the IEPOX pathway. The IEPOX-SOA factor loadings correlated with independently measured mass concentrations of tracers of IEPOX-derived PM, namely C 5 -alkene triols and 2-methyltetrols ( R = 0.96 and 0.78, respectively). The factor loading, as well as the ratio f of the loading to organic PM mass concentration, decreased under polluted compared to background conditions. For an increase in NO y concentration from 0.5 to 2 ppb, the factor loading and f decreased by two to three fold. Overall, sulfate concentration explained 37 % of the variability in the factor loading. After segregation of factor loading into subsets based on NO y concentration, the sulfate concentration explained up to 75 % of the variability. Considering both factors, the data sets show that the suppressing effects of increased NO concentrations dominated over the enhancing effects of higher sulfate concentrations. Furthermore, the pollution from Manaus elevated NO y concentrations more significantly than sulfate concentrations relative to background conditions. In this light, increased emissions of nitrogen oxides, as anticipated for some scenarios of Amazonian economic development, could significantly alter pathways of PM production that presently prevail over the tropical forest, implying changes to air quality and regional climate.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Influence of urban pollution on the production of organic particulate matter from isoprene epoxydiols in central Amazonia

The atmospheric chemistry of isoprene contributes to the production of a substantial mass fraction of the particulate matter (PM) over tropical forests. Isoprene epoxydiols (IEPOX) produced in the gas phase by the oxidation of isoprene under HO2-dominant conditions are subsequently taken up by particles, thereby leading to production of secondary organic PM. The present study investigates possible perturbations to this pathway by urban pollution. The measurement site in central Amazonia was located 4 to 6 hours downwind of Manaus, Brazil. Measurements took place from February through March 2014 of the wet season, as part of the GoAmazon2014/5 experiment. Mass spectra of organic PM collected with an Aerodyne Aerosol Mass Spectrometer were analyzed by positive-matrix factorization. One resolved statistical factor (“IEPOX-SOA factor”) was associated with PM production by the IEPOX pathway. Loadings of this factor correlated with independently measured mass concentrations of tracers of IEPOX-derived PM, namely C5-alkene triols and 2-methyltetrols (R =0.96 and 0.78, respectively). Factor loading, as well as the ratio of the factor loading to organic PM mass concentration, decreased under polluted compared to background conditions. For the study period, sulfate concentration explained 37 % of the variability in the factor loading. After segregation of the data set by NOy concentration, the sulfate concentration explained up to 75 % of the variability in factor loading within the NOy subsets. The sulfate-detrended IEPOX-SOA factor loading decreased by two- to three-fold for an increase in NOy concentration from 0.5 to 2 ppb. The suppressing effects of elevated NO dominated over the enhancing effects of higher sulfate with respect to the production of IEPOX-derived PM. Relative to background conditions, the Manaus pollution contributed more significantly to NOy than to sulfate. In this light, increased emissions of nitrogen oxides, as anticipated for some scenarios of Amazonian economic development, could significantly alter pathways of PM production that presently prevail over the tropical forest, implying changes to air quality and regional climate.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Extending a Tandem Mass Spectral Library to Include MS{sup 2} Spectra of Fragment Ions Produced In-Source and MS{sup n} Spectra

Tandem mass spectral library searching is finding increased use as an effective means of determining chemical identity in mass spectrometry-based omics studies. We previously reported on constructing a tandem mass spectral library that includes spectra for multiple precursor ions for each analyte. Here we report our method for expanding this library to include MS{sup 2} spectra of fragment ions generated during the ionization process (in-source fragment ions) as well as MS{sup 3} and MS{sup 4} spectra. These can assist the chemical identification process. A simple density-based clustering algorithm was used to cluster all significant precursor ions from MS{sup 1} scans for an analyte acquired during an infusion experiment. The MS{sup 2} spectra associated with these precursor ions were grouped into the same precursor clusters. Subsequently, a new top-down hierarchical divisive clustering algorithm was developed for clustering the spectra from fragmentation of ions in each precursor cluster, including the MS{sup 2} spectra of the original precursors and of the in-source fragments as well as the MS{sup n} spectra. This algorithm starts with all the spectra of one precursor in one cluster and then separates them into sub-clusters of similar spectra based on the fragment patterns. Herein, we describe the algorithms and spectral evaluation methods for extending the library. The new library features were demonstrated by searching the high resolution spectra of E. coli extracts against the extended library, allowing identification of compounds and their in-source fragment ions in a manner that was not possible before. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Rapid paper spray mass spectrometry characterization of uranium and exemplar molecular species

The ability to detect and quantify the presence of specific inorganic elements and complexes is essential for environmental monitoring and nuclear safeguards applications. In this work, paper spray ionization mass spectrometry (PSI–MS) was used for the rapid chemical and isotopic characterization of trace inorganic species collected on cotton swipe substrates. Here, the direct analysis of cotton swipes using this ambient ionization technique led to fast sample analysis that retained original chemical information of the source material with minimal sample preparation. Mass spectra were collected on an atmospheric pressure ionization, high–resolution mass spectrometer for solutions containing uranyl acetate, uranyl chloride, uranyl nitrate, and uranyl tri– n –butylphosphate (uranyl–TBP) complexes. Gadolinium nitrate was used as an internal standard for the quantitative analysis of uranium. To demonstrate the ability to characterize inorganic contaminants in the presence of uranium, a multi–element inorganic standard containing U, Bi, Pb, Cd, Fe, and Zn was deposited onto cotton substrates and directly analyzed without purification. All elements doped on the cotton substrate were detected with strong signal–to–noise (S/N) ratios (S/N~1000 for UO 2 + on multi–element doped swipes) and high integrated intensities (>10 5 counts) from collection periods of approximately 1 min. Limits of detection were determined to be approximately 94 ng for UO 2 + and uranyl acetate through the measurement of ppb level solutions. The rapid analysis of uranium and other inorganic–containing samples while still retaining original chemical information (e.g. uranyl complexation) was demonstrated. Qualitative detection and speciation were achieved in less than 1 min of analysis. For uranium isotopic quantitation, longer accumulations (>15 min) can be sustained to improve the accuracy of minor 235 U isotopic abundance measurements to approximately 1% error.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Excitation energy dependence of fragment-mass distributions from fission of 180,190 Hg formed in fusion reactions of 36 Ar + 144,154 Sm

Mass distributions of fission fragments from the compound nuclei 180 Hg and 190 Hg formed in fusion reactions 36 Ar + 144 Smand 36 Ar + 154 Sm, respectively, were measured at initial excitation energies of E* ( 180 Hg) = 33-66 MeV and E* ( 190 Hg) = 48-71 MeV. In the fission of 180 Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses $\overline{A}_L$ / $\overline{A}_H$ = 79/101. The mass asymmetry for 180 Hg agrees well with that obtained in the low-energy β + /EC-delayed fission of 180 Tl, from our earlier ISOLDE(CERN) experiment. Fission of 190 Hg is found to proceed in a similar way, delivering the mass asymmetry of $\overline{A}_L$ / $\overline{A}_H$ = 83/107, throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40 MeV. In conclusion, this behavior is different from fission of actinide nuclei and heavier mercury isotope 198 Hg.

(180↗
NASA NTRS1988

Synopsis of a computer program designed to interface a personal computer with the fast data acquisition system of a time-of-flight mass spectrometer

Briefly described are the essential features of a computer program designed to interface a personal computer with the fast, digital data acquisition system of a time-of-flight mass spectrometer. The instrumentation was developed to provide a time-resolved analysis of individual vapor pulses produced by the incidence of a pulsed laser beam on an ablative material. The high repetition rate spectrometer coupled to a fast transient recorder captures complete mass spectra every 20 to 35 microsecs, thereby providing the time resolution needed for the study of this sort of transient event. The program enables the computer to record the large amount of data generated by the system in short time intervals, and it provides the operator the immediate option of presenting the spectral data in several different formats. Furthermore, the system does this with a high degree of automation, including the tasks of mass labeling the spectra and logging pertinent instrumental parameters.

Bechtel, R. D.↗
DOE OSTI2019

The Borg Cube Simulation: Cosmological Hydrodynamics with CRK-SPH

A challenging requirement posed by next-generation observations is a firm theoretical grasp of the impact of baryons on structure formation. Cosmological hydrodynamic simulations modeling gas physics are vital in this regard. A high degree of modeling flexibility exists in this space, making it important to explore a range of methods in order to gauge the accuracy of simulation predictions. We present results from the first cosmological simulation using Conservative Reproducing Kernel Smoothed Particle Hydrodynamics (CRK-SPH). We employ two simulations: one evolved purely under gravity, and the other with nonradiative hydrodynamics. Each contains 2 × 2304 3 cold dark matter plus baryon particles in an 800 h -1 Mpc box. We compare statistics to previous nonradiative simulations including power spectra, mass functions, baryon fractions, and concentration. We find self-similar radial profiles of gas temperature, entropy, and pressure and show that a simple analytic model recovers these results to better than 40% over two orders of magnitude in mass. We quantify the level of nonthermal pressure support in halos and demonstrate that hydrostatic mass estimates are biased low by 24% (10%) for halos of mass 10 15 (10 13 ) h -1 M⊙. Here, we compute angular power spectra for the thermal and kinematic Sunyaev–Zel’dovich effects and find good agreement with the low-ℓ Planck measurements. Finally, artificial scattering between particles of unequal mass is shown to have a large impact on the gravity-only run, and we highlight the importance of better understanding this issue in hydrodynamic applications. This is the first in a simulation campaign using CRK-SPH, with future work including subresolution gas treatments.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

High-dimensional isotomics, part 2: Observations of over 100 constraints on methionine's isotome

The abundances of different isotopic forms of a compound, or isotopologues, will vary based on its physical and chemical history. The number of isotopologues increases combinatorically with the size of a molecule, and even small molecules such as amino acids have thousands of potentially observable isotopic variants. However, due to the analytical challenges of separating and observing isotopologues, only a few dimensions of isotopic diversity are routinely measured. Overcoming these challenges requires both an experimental method to observe many isotopic properties and a theoretical framework for interpreting these experiments. In Part 1, we presented such a theoretical framework; here, we demonstrate an experimental method, which we apply to methionine. Our approach uses a Q Exactive HF Orbitrap to perform several “M + N experiments”, where a sample is ionized, a subset of its isotopologues with cardinal mass N daltons greater than the unsubstituted isotopologue is selected and fragmented, and the proportions of all detectable isotopic forms of those fragment ions are quantified. We perform M + 1, M + 2, M + 3, and M + 4 experiments of a methionine sample and standard where the sample has a 100 ‰ enrichment of 13C at the methyl carbon relative to the natural 13C abundance at that position in the standard, and is otherwise identical to the standard. We observe isotopic forms of 8 fragment ion species for each version of the M + N experiment. With the assistance of a forward model of expected mass spectra, we identify isotopic peaks for each fragment ion based on observed mass and abundance, screen these for data quality, and quantify abundances for 146 unique isotopic peaks at precisions of ≈ 0.3–3 ‰. We present our direct observations and use them to reconstruct the concentrations of 19 individual singly, doubly, and triply-substituted isotopologues; doing so gives fewer constraints and broader error bars than working with the direct observations, but may be more interpretable for some applications. We also examine possibilities for measuring additional peaks, which are primarily limited by the detection limit of the Orbitrap-IRMS method. We then suggest some possible uses of our direct measurements for chemical forensics and hypothesis testing. Furthermore, our results demonstrate the diversity of isotopic constraints currently observable and interpretable for organic molecules.

58 GEOSCIENCES↗
DOE OSTI2016

GoAmazon 2014/15 Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) Field Campaign Report

The Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) deployment to the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility T3 site in Manacapuru, Brazil, was motivated by two main scientific objectives of the Green Ocean Amazon (GoAmazon) 2014/15 field campaign. 1) Study the interactions between anthropogenic and biogenic emissions by determining important molecular species in ambient nanoparticles. To address this, TDCIMS data will be combined with coincident measurements such as gas-phase sulfuric acid to determine the contribution of sulfuric acid condensation to nucleation and growth. We can then compare that result to TDCIMS-derived nanoparticle composition to determine the fraction of growth that can be attributed to the uptake of organic compounds. The molecular composition of sampled particles will also be used to attribute specific chemical species and mechanisms to growth, such as the condensation of low-volatility species or the oligomerization of α-dicarbonyl compounds. 2) Determine the source of new ambient nanoparticles in the Amazon. The hypothesis prior to measurements was that potassium salts formed from the evaporation of primary particles emitted by fungal spores can provide a unique and important pathway for new particle production in the Amazon basin. To explore this hypothesis, the TDCIMS recorded the mass spectra of sampled ambient particles using a protonated water cluster Chemical Ionization Mass Spectrometer (CIMS). Laboratory tests performed using potassium salts show that the TDCIMS can detect potassium with high sensitivity with this technique.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Ion Mobility – Mass Spectrometry Rapid Imaging of Special Nuclear Materials

Robot Nose will use new fast data throughput methods and experience with laser microfocus to dramatically improve the speed and spatial resolution of an established instrument, making it a useful tool for imaging special nuclear materials (SNM). Mass spectrometry imaging instruments have traditionally been too slow and mass alone is generally an insufficient measurement for organic analyses. This situation was markedly improved by Ionwerks Inc., who pioneered the combination of ion mobility with mass spectrometry imaging. In 2D mobility-mass plots, clearly identifiable trend lines can be selected and reduced to 1D mass spectra without isobaric interferences. This is a major advantage over other imaging mass spectrometers that generally cannot distinguish isobars without custom-built lasers or high voltage accelerators. Special nuclear material (SNM) contains substantial fissile isotopes, particularly 233U, 235U, and 239Pu. A complete forensic analysis of SNM therefore requires quantitative isotopic measurement – often through some form of mass spectrometry. SNM contaminated with inclusions such as pollen grains can help identify its prior locations. The project team is presently working on an approach to allow rapid screening of 1-3 cm diameter thin samples of such material.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗