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Sample records for light sn isotopes

  1. Quadrupole Collectivity in Neutron Deficient Sn Isotopes

    NASA Astrophysics Data System (ADS)

    Gade, Alexandra

    2014-03-01

    One of the overarching goals of nuclear physics is the development of a comprehensive model of the atomic nucleus with predictive power across the nuclear chart. Of particular importance for the development of nuclear models is experimental data that consistently track the effect of isospin and changed binding, for example. The chain of Sn isotopes has been a formidable testing ground for nuclear models as some spectroscopic data is available from N = Z = 50 100Sn in the proximity of the proton dripline to 134Sn, beyond the very neutron-rich doubly magic nucleus 132Sn. In even-even nuclei, the electromagnetic quadrupole excitation strength is a measure of quadrupole collectivity, sensitive to the presence of shell gaps, nuclear deformation, and nucleon-nucleon correlations, for example. In the Sn isotopes, this transition strength has been reported from 104Sn to 130Sn, spanning a chain of 14 even-even Sn isotopes. The trend is asymmetric with respect to midshell and not even the largest-scale shell-model calculations have been able to describe the evolution of transition strength across the isotopic chain without varying effective charges. Implications will be discussed. This work was supported by the National Science Foundation under Grant No. PHY-1102511.

  2. Shell model calculation for Te and Sn isotopes in the vicinity of {sup 100}Sn

    SciTech Connect

    Yakhelef, A.; Bouldjedri, A.

    2012-06-27

    New Shell Model calculations for even-even isotopes {sup 104-108}Sn and {sup 106,108}Te, in the vicinity of {sup 100}Sn have been performed. The calculations have been carried out using the windows version of NuShell-MSU. The two body matrix elements TBMEs of the effective interaction between valence nucleons are obtained from the renormalized two body effective interaction based on G-matrix derived from the CD-bonn nucleon-nucleon potential. The single particle energies of the proton and neutron valence spaces orbitals are defined from the available spectra of lightest odd isotopes of Sb and Sn respectively.

  3. Inelastic proton scattering of Sn isotopes studied with GRETINA

    NASA Astrophysics Data System (ADS)

    Campbell, Christopher

    2014-03-01

    The chain of semi-magic Sn nuclei, with many stable isotopes, has been a fertile ground for experimental and theoretical studies. Encompassing a major neutron shell from N = 50 to 82, the properties and structure of these nuclei provided important data for the development of the pairing-plus-quadrupole model. Recent experimental information on B(E2) for 106,108,110,112Sn came as a surprise as it indicated a larger collectivity than the predicted parabolic trend of quadrupole collectivity. These data, instead, show an unexpectedly flat trend even as the number of valence particles is reduced from 12 to 6. To fully understand how collectivity is evolving in these isotopes, 108,110,112Sn have been studied using thick-target, inelastic proton scattering with GRETINA tagging inelastic scattering events by detecting gamma-rays from the prompt decay of states excited in the reaction. We will present the trend of 2 + excitation cross-sections, the deduced quadrupole deformation parameters, and observations of other low-lying collective states. Comparison of these (p,p') quadrupole deformation parameters with B(E2) data will provide new insights into the relative importance of proton and neutron contributions to collectivity in these nuclei. GRETINA was funded by the US DOE - Office of Science. Operation of the array at NSCL is supported by NSF under Cooperative Agreement PHY-1102511(NSCL) and DOE under grant DE-AC02-05CH11231(LBNL).

  4. (Si)GeSn nanostructures for light emitters

    NASA Astrophysics Data System (ADS)

    Rainko, D.; Stange, D.; von den Driesch, N.; Schulte-Braucks, C.; Mussler, G.; Ikonic, Z.; Hartmann, J. M.; Luysberg, M.; Mantl, S.; Grützmacher, D.; Buca, D.

    2016-05-01

    Energy-efficient integrated circuits for on-chip or chip-to-chip data transfer via photons could be tackled by monolithically grown group IV photonic devices. The major goal here is the realization of fully integrated group IV room temperature electrically driven lasers. An approach beyond the already demonstrated optically-pumped lasers would be the introduction of GeSn/(Si)Ge(Sn) heterostructures and exploitation of quantum mechanical effects by reducing the dimensionality, which affects the density of states. In this contribution we present epitaxial growth, processing and characterization of GeSn/(Si)Ge(Sn) heterostructures, ranging from GeSn/Ge multi quantum wells (MQWs) to GeSn quantum dots (QDs) embedded in a Ge matrix. Light emitting diodes (LEDs) were fabricated based on the MQW structure and structurally analyzed via TEM, XRD and RBS. Moreover, EL measurements were performed to investigate quantum confinement effects in the wells. The GeSn QDs were formed via Sn diffusion /segregation upon thermal annealing of GeSn single quantum wells (SQW) embedded in Ge layers. The evaluation of the experimental results is supported by band structure calculations of GeSn/(Si)Ge(Sn) heterostructures to investigate their applicability for photonic devices.

  5. Origin of Isotopically Light Nitrogen in Meteorites

    NASA Astrophysics Data System (ADS)

    Verchovsky, A. B.

    2016-08-01

    Carrier of planetary noble gases, Q, also contains isotopically light N with d15N < -150‰ and is responsible for the appearance of the light N in many types of meteorites such as CR, CO, CM and ureilites.

  6. Low-energy electric dipole response of Sn isotopes

    NASA Astrophysics Data System (ADS)

    Papakonstantinou, P.; Hergert, H.; Ponomarev, V. Yu.; Roth, R.

    2014-03-01

    We study the low-energy dipole (LED) strength distribution along the Sn isotopic chain in both the isoscalar (IS) and the isovector (IV, or E1) electric channels, to provide testable predictions and guidance for new experiments with stable targets and radioactive beams. We use the self-consistent quasi-particle random-phase approximation (QRPA) with finite-range interactions and mainly the Gogny D1S force. We analyze also the performance of a realistic two-body interaction supplemented by a phenomenological three-body contact term. We find that from N =50 and up to the N =82 shell closure (132Sn) the lowest-energy part of the IS-LED spectrum is dominated by a collective transition whose properties vary smoothly with neutron number and which cannot be interpreted as a neutron-skin oscillation. For the neutron-rich species this state contributes to the E1 strength below particle threshold, but much more E1 strength is carried by other, weak but numerous transitions around or above threshold. We find that strong structural changes in the spectrum take effect beyond N =82, namely increased LED strength and lower excitation energies. Our results with the Gogny interaction are compatible with existing data. On this basis we predict that (a) the summed IS strength below particle threshold shall be of the same order of magnitude for N =50-82, (b) the summed E1 strength up to approximately 12 MeV shall be similar for N =50-82 MeV, while (c) the summed E1 strength below threshold shall be of the same order of magnitude for N ≈64-82 and much weaker for the lighter, more-symmetric isotopes. We point out a general agreement of our results with other nonrelativistic studies, the absence of a collective IS mode in some of those studies, and a possibly radical disagreement with relativistic models.

  7. New lifetime measurements in the stable semimagic Sn isotopes using the Doppler-shift attenuation technique

    NASA Astrophysics Data System (ADS)

    Jungclaus, A.; Walker, J.; Leske, J.; Speidel, K.-H.; Stuchbery, A. E.; East, M.; Boutachkov, P.; Cederkäll, J.; Doornenbal, P.; Egido, J. L.; Ekström, A.; Gerl, J.; Gernhäuser, R.; Goel, N.; Górska, M.; Kojouharov, I.; Maier-Komor, P.; Modamio, V.; Naqvi, F.; Pietralla, N.; Pietri, S.; Prokopowicz, W.; Schaffner, H.; Schwengner, R.; Wollersheim, H.-J.

    2011-09-01

    Precise measurements of lifetimes in the picosecond range of excited states in the stable even-A Sn isotopes 112,114,116,122Sn have been performed using the Doppler shift attenuation technique. For the first excited 2+ states in 112Sn, 114Sn and 116Sn the E2 transition strengths deduced from the measured lifetimes are in disagreement with the previously adopted values. They indicate a shallow minimum at N = 66 in contrast to the maximum at mid-shell predicted by modern shell model calculations.

  8. Light echoes and transient luminescence near SN 1987A

    NASA Technical Reports Server (NTRS)

    Crotts, Arlin P. S.; Kunkel, William E.; Mccarthy, Patrick J.

    1989-01-01

    The discovery of two new light echoes from sheets of material behind supernova 1987A and present images of the progenitor's circumstellar shell are reported, indicating diffuse echoes from the star's red giant wind. The echo sheets' geometry explains well the behavior of SN 1987's 10-micron flux, but the circumstellar shell appears to be 70 percent larger than the prediction from the analysis of narrow UV emission lines. The sheets' recombination time show them relatively thin and dense. The data also constrain the existence of any fourth star in the Sanduleak -69 deg 202 system and show that the feature reported 8 arcsecs from the supernova is probably not an echo from a thin sheet in SN 1987A's foreground.

  9. Genetic and molecular analysis of Sn, a light-inducible, tissue specific regulatory gene in maize.

    PubMed

    Tonelli, C; Consonni, G; Dolfini, S F; Dellaporta, S L; Viotti, A; Gavazzi, G

    1991-03-01

    The Sn locus of maize is functionally similar to the R and B loci, in that Sn differentially controls the tissue-specific deposition of anthocyanin pigments in certain seedling and plant cells. We show that Sn shows molecular similarity to the R gene and have used R DNA probes to characterize several Sn alleles. Northern analysis demonstrates that all Sn alleles encode a 2.5 kb transcript, which is expressed in a tissue-specific fashion consistent with the distribution of anthocyanins. Expression of the Sn gene is light-regulated. However, the Sn: bol3 allele allows Sn mRNA transcription to occur in the dark, leading to pigmentation in dark-grown seedlings and cob integuments. We report the isolation of genomic and cDNA clones of the light-independent Sn: bol3 allele. Using Sn cDNA as a probe, the spatial and temporal expression of Sn has been examined. The cell-specific localization of Sn mRNA has been confirmed by in situ hybridization using labelled antisense RNA probes. According to its proposed regulatory role, expression of Sn precedes and, in turn, causes a coordinate and tissue-specific accumulation of mRNA of structural genes for pigment synthesis and deposition, such as A1 and C2. The functional and structural relationship between R, B, Lc and Sn is discussed in terms of an evolutionary derivation from a single ancestral gene which gave rise this diverse gene family by successive duplication events.

  10. New Isotopes and Proton Emitters-Crossing the Drip Line in the Vicinity of 100Sn

    NASA Astrophysics Data System (ADS)

    Čeliković, I.; Lewitowicz, M.; Gernhäuser, R.; Krücken, R.; Nishimura, S.; Sakurai, H.; Ahn, D. S.; Baba, H.; Blank, B.; Blazhev, A.; Boutachkov, P.; Browne, F.; de France, G.; Doornenbal, P.; Faestermann, T.; Fang, Y.; Fukuda, N.; Giovinazzo, J.; Goel, N.; Górska, M.; Ilieva, S.; Inabe, N.; Isobe, T.; Jungclaus, A.; Kameda, D.; Kim, Y.-K.; Kwon, Y. K.; Kojouharov, I.; Kubo, T.; Kurz, N.; Lorusso, G.; Lubos, D.; Moschner, K.; Murai, D.; Nishizuka, I.; Park, J.; Patel, Z.; Rajabali, M.; Rice, S.; Schaffner, H.; Shimizu, Y.; Sinclair, L.; Söderström, P.-A.; Steiger, K.; Sumikama, T.; Suzuki, H.; Takeda, H.; Wang, Z.; Watanabe, H.; Wu, J.; Xu, Z.

    2016-04-01

    Several new isotopes, 96In, 94Cd, 92Ag, and 90Pd, have been identified at the RIKEN Nishina Center. The study of proton drip-line nuclei in the vicinity of 93Ag and 89Rh with half-lives in the submicrosecond range. The systematics of the half-lives of odd-Z nuclei with Tz=-1 /2 toward 99Sn shows a stabilizing effect of the Z =50 shell closure. Production cross sections for nuclei in the vicinity of 100Sn measured at different energies and target thicknesses were compared to the cross sections calculated by epax taking into account contributions of secondary reactions in the primary target.

  11. Fusion reactions in collisions induced by Li isotopes on Sn targets

    SciTech Connect

    Fisichella, M.; Shotter, A. C.; Di Pietro, A.; Figuera, P.; Lattuada, M.; Marchetta, C.; Musumarra, A.; Pellegriti, M. G.; Ruiz, C.; Scuderi, V.; Strano, E.; Torresi, D.; Zadro, M.

    2012-10-20

    Fusion cross sections for the {sup 6}Li+{sup 120}Sn and {sup 7}Li+{sup 119}Sn systems have been measured. We aim to search for possible effects due to the different neutron transfer Q-values, by comparing the fusion cross sections for the two systems below the barrier. This experiment is the first step of a wider systematic aiming to study the above problems in collisions induced by stable and unstable Li isotopes on tin all forming the same compound nucleus.

  12. New Isotopes and Proton Emitters-Crossing the Drip Line in the Vicinity of ^{100}Sn.

    PubMed

    Čeliković, I; Lewitowicz, M; Gernhäuser, R; Krücken, R; Nishimura, S; Sakurai, H; Ahn, D S; Baba, H; Blank, B; Blazhev, A; Boutachkov, P; Browne, F; de France, G; Doornenbal, P; Faestermann, T; Fang, Y; Fukuda, N; Giovinazzo, J; Goel, N; Górska, M; Ilieva, S; Inabe, N; Isobe, T; Jungclaus, A; Kameda, D; Kim, Y-K; Kwon, Y K; Kojouharov, I; Kubo, T; Kurz, N; Lorusso, G; Lubos, D; Moschner, K; Murai, D; Nishizuka, I; Park, J; Patel, Z; Rajabali, M; Rice, S; Schaffner, H; Shimizu, Y; Sinclair, L; Söderström, P-A; Steiger, K; Sumikama, T; Suzuki, H; Takeda, H; Wang, Z; Watanabe, H; Wu, J; Xu, Z

    2016-04-22

    Several new isotopes, ^{96}In, ^{94}Cd, ^{92}Ag, and ^{90}Pd, have been identified at the RIKEN Nishina Center. The study of proton drip-line nuclei in the vicinity of ^{100}Sn led to the discovery of new proton emitters ^{93}Ag and ^{89}Rh with half-lives in the submicrosecond range. The systematics of the half-lives of odd-Z nuclei with T_{z}=-1/2 toward ^{99}Sn shows a stabilizing effect of the Z=50 shell closure. Production cross sections for nuclei in the vicinity of ^{100}Sn measured at different energies and target thicknesses were compared to the cross sections calculated by epax taking into account contributions of secondary reactions in the primary target. PMID:27152796

  13. Alpha-decay of light protactinium isotopes

    SciTech Connect

    Faestermann, T.; Gillitzer, A.; Hartel, K.; Henning, W.; Kienle, P.

    1987-12-10

    Light protactinium isotopes have been produced with /sup 204/Pb (/sup 19/F,xn) reactions. ..cap alpha..-activities with E/sub ..cap alpha../ = 9.90(5) MeV, T/sub 1/2/ = 53(10) ns and E/sub ..cap alpha../ = 9.65(5) MeV, T/sub 1/2/ = 0.78(16) ..mu..s could be attributed to the previously unobserved nuclei /sup 219/Pa and /sup 220/Pa with the help of excitation functions. The peak cross sections for the 4n and 3n evaporation channels are on the order of 10 ..mu..b. The decay energies as well as the halflives fit well into the systematics of these nuclei close to the magic neutron number N = 126. /sup 219/Pa is the shortest lived nuclide known with directly measured halflife.

  14. Predicted isotopic variation in surface α clustering in Sn compared with (d ,6Li ) pickup yields

    NASA Astrophysics Data System (ADS)

    Cowley, A. A.

    2016-05-01

    Based on a generalized relativistic mean-field model, α clustering on the surface of Sn was recently predicted to vary systematically as a function of isotopic mass. Existing experimental information from (d ,6Li ) cluster pickup is now used to verify the predicted trend. The extent of the anticipated validity of such a comparison between the experimental results and the theoretical formulation is evaluated and discussed in the present paper.

  15. E2 transition probabilities for decays of isomers observed in neutron-rich odd Sn isotopes

    DOE PAGES

    Iskra, Ł. W.; Broda, R.; Janssens, R. V.F.; Wrzesiński, J.; Chiara, C. J.; Carpenter, M. P.; Fornal, B.; Hoteling, N.; Kondev, F. G.; Królas, W.; et al

    2015-01-01

    High-spin states were investigated with gamma coincidence techniques in neutron-rich Sn isotopes produced in fission processes following ⁴⁸Ca + ²⁰⁸Pb, ⁴⁸Ca + ²³⁸U, and ⁶⁴Ni + ²³⁸U reactions. By exploiting delayed and cross-coincidence techniques, level schemes have been delineated in odd ¹¹⁹⁻¹²⁵Sn isotopes. Particular attention was paid to the occurrence of 19/2⁺ and 23/2⁺ isomeric states for which the available information has now been significantly extended. Reduced transition probabilities, B(E2), extracted from the measured half-lives and the established details of the isomeric decays exhibit a striking regularity. This behavior was compared with the previously observed regularity of the B(E2) amplitudesmore » for the seniority ν = 2 and 3, 10⁺ and 27/2⁻ isomers in even- and odd-Sn isotopes, respectively.« less

  16. E2 transition probabilities for decays of isomers observed in neutron-rich odd Sn isotopes

    SciTech Connect

    Iskra, Ł. W.; Broda, R.; Janssens, R. V.F.; Wrzesiński, J.; Chiara, C. J.; Carpenter, M. P.; Fornal, B.; Hoteling, N.; Kondev, F. G.; Królas, W.; Lauritsen, T.; Pawłat, T.; Seweryniak, D.; Stefanescu, I.; Walters, W. B.; Zhu, S.

    2015-01-01

    High-spin states were investigated with gamma coincidence techniques in neutron-rich Sn isotopes produced in fission processes following ⁴⁸Ca + ²⁰⁸Pb, ⁴⁸Ca + ²³⁸U, and ⁶⁴Ni + ²³⁸U reactions. By exploiting delayed and cross-coincidence techniques, level schemes have been delineated in odd ¹¹⁹⁻¹²⁵Sn isotopes. Particular attention was paid to the occurrence of 19/2⁺ and 23/2⁺ isomeric states for which the available information has now been significantly extended. Reduced transition probabilities, B(E2), extracted from the measured half-lives and the established details of the isomeric decays exhibit a striking regularity. This behavior was compared with the previously observed regularity of the B(E2) amplitudes for the seniority ν = 2 and 3, 10⁺ and 27/2⁻ isomers in even- and odd-Sn isotopes, respectively.

  17. Gamma-ray emission from SN2014J near maximum optical light

    NASA Astrophysics Data System (ADS)

    Isern, J.; Jean, P.; Bravo, E.; Knödlseder, J.; Lebrun, F.; Churazov, E.; Sunyaev, R.; Domingo, A.; Badenes, C.; Hartmann, D. H.; Hoeflich, P.; Renaud, M.; Soldi, S.; Elias-Rosa, N.; Hernanz, M.; Domínguez, I.; García-Senz, D.; Lichti, G. G.; Vedrenne, G.; Von Ballmoos, P.

    2016-04-01

    Context. The optical light curve of Type Ia supernovae (SNIa) is powered by thermalized gamma-rays produced by the decay of 56Ni and 56Co, the main radioactive isotopes synthesized by the thermonuclear explosion of a C/O white dwarf. Aims: Gamma-rays escaping the ejecta can be used as a diagnostic tool for studying the characteristics of the explosion. In particular, it is expected that the analysis of the early gamma emission, near the maximum of the optical light curve, could provide information about the distribution of the radioactive elements in the debris. Methods: The gamma data obtained from SN2014J in M 82 by the instruments on board INTEGRAL were analysed paying special attention to the effect that the detailed spectral response has on the measurements of the intensity of the lines. Results: The 158 keV emission of 56Ni has been detected in SN2014J at ~5σ at low energy with both ISGRI and SPI around the maximum of the optical light curve. After correcting the spectral response of the detector, the fluxes in the lines suggest that, in addition to the bulk of radioactive elements buried in the central layers of the debris, there is a plume of 56Ni, with a significance of ~3σ, moving at high velocity and receding from the observer. The mass of the plume is in the range of ~0.03-0.08 M⊙. Conclusions: No SNIa explosion model has ever predicted the mass and geometrical distribution of 56Ni suggested here. According to its optical properties, SN2014J looks like a normal SNIa, so it is extremely important to discern whether it is also representative in the gamma-ray band. Based on observations with INTEGRAL, an ESA project with instruments and the science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, and Spain), the Czech Republic, and Poland and with the participation of Russia and USA.

  18. The Detection of a Light Echo from Type Ia SN 2007af in NGC 5584

    NASA Astrophysics Data System (ADS)

    Drozdov, Dina; Leising, M. D.; Milne, P.; Riess, A. G.

    2013-06-01

    We report the discovery of a light echo (LE) at t ~1000 days past maximum from the normal Type Ia supernova (SNe Ia) SN 2007af in the spiral galaxy NGC 5584. The presence of a LE is supported by photometric data and analysis of the images acquired during the Cepheid campaign using the Hubble Space Telescope (HST) Wide Field Camera 3 (Riess et al. 2011). The F350 and F555 images show a distinct ring-like structure with an additional central source. The images, taken months apart, show an evolution of the ring structure, which is consistent with a growing light echo in time. We find an angular radius of the outer echo to be ~0.29'' - 0.36''. Using the Cepheid distance to NGC 5584 of 24 Mpc, we find the dust illuminated by the light echo to be at a distance ~800 pc from the supernova. This rare discovery adds to the select few light echoes found in Type Ia SNe: SN 1572, SN 1991T, SN 1995E, SN 1998bu, and SN 2006X. Light echoes are powerful tools that probe the environment around supernovae, determine dust properties and characteristics, and could provide constraints on the progenitors, which are not fully understood for SN Ia.

  19. HELIX: The High Energy Light Isotope Experiment

    NASA Astrophysics Data System (ADS)

    Tarle, Gregory

    This is the lead proposal for a new suborbital program, HELIX (High-Energy Light Isotope eXperiment), designed to make measurements of the isotopic composition of light cosmic-ray nuclei from ~200 MeV/nuc to ~10 GeV/nuc. Past measurements of this kind have provided profound insights into the nature and origin of cosmic rays, revealing, for instance, information on acceleration and confinement time scales, and exposing some conspicuous discrepancies between solar and cosmic-ray abundances. The most detailed information currently available comes from the ACE/CRIS mission, but is restricted to energies below a few 100 MeV/nuc. HELIX aims at extending this energy range by over an order of magnitude, where, in most cases, no measurements of any kind exist, and where relativistic time dilation affects the apparent lifetime of radioactive clock nuclei. The HELIX measurements will provide essential information for understanding the propagation history of cosmic rays in the galaxy. This is crucial for properly interpreting several intriguing anomalies reported in recent cosmic-ray measurements, pertaining to the energy spectra of protons, helium, and heavier nuclei, and to the anomalous rise in the positron fraction at higher energy. HELIX employs a high-precision magnet spectrometer to provide measurements which are not achievable by any current or planned instrument. The superconducting magnet originally used for the HEAT payload in five successful high-altitude flights will be combined with state-of-the-art detectors to measure the charge, time-of-flight, magnetic rigidity, and velocity of cosmic-ray particles with high precision. The instrumentation includes plastic scintillators, silicon-strip detectors repurposed from Fermilab's CDF detector, a high-performance gas drift chamber, and a ring-imaging Cherenkov counter employing aerogel radiators and silicon photomultipliers. To reduce cost and technical risk, the HELIX program will be structured in two stages. The first

  20. Z=50 Shell Gap near {sup 100}Sn from Intermediate-Energy Coulomb Excitations in Even-Mass {sup 106-112}Sn Isotopes

    SciTech Connect

    Vaman, C.; Bazin, D.; Galaviz, D.; Mueller, W. F.; Schiller, A.; Stolz, A.; Andreoiu, C.; Becerril, A.; Brown, B. A.; Campbell, C. M.; Chester, A.; Cook, J. M.; Dinca, D. C.; Gade, A.; Glasmacher, T.; Miller, D.; Moeller, V.; Starosta, K.; Terry, J. R.; Zelevinsky, V.

    2007-10-19

    Rare isotope beams of neutron-deficient {sup 106,108,110}Sn from the fragmentation of {sup 124}Xe were employed in an intermediate-energy Coulomb excitation experiment. The measured B(E2,0{sub 1}{sup +}{yields}2{sub 1}{sup +}) values for {sup 108}Sn and {sup 110}Sn and the results obtained for the {sup 106}Sn show that the transition strengths for these nuclei are larger than predicted by current state-of-the-art shell-model calculations. This discrepancy might be explained by contributions of the protons from within the Z=50 shell to the structure of low-energy excited states in this region.

  1. Quantitative study of coherent pairing modes with two-neutron transfer: Sn isotopes

    NASA Astrophysics Data System (ADS)

    Potel, G.; Idini, A.; Barranco, F.; Vigezzi, E.; Broglia, R. A.

    2013-05-01

    Pairing rotations and pairing vibrations are collective modes associated with a field, the pair field, which changes the number of particles by two. Consequently, they can be studied at profit with the help of two-particle transfer reactions in superfluid and in normal nuclei, respectively. The advent of exotic beams has opened, for the first time, the possibility to carry out such studies in medium heavy nuclei, within the same isotopic chain. The case studied in the present paper is that of the Sn isotopes [essentially from closed (Z=N=50) to closed (Z=50, N=82) shells]. The static and dynamic off-diagonal, long-range order phase coherence in gauge space displayed by pairing rotations and vibrations, respectively, leads to coherent states which behave almost classically. Consequently, these modes are amenable to an accurate nuclear structure description in terms of simple models containing the right physics, in particular, BCS plus quasiparticle random-phase approximation and Hartree-Fock mean field plus random-phase approximation, respectively. The associated two-nucleon transfer spectroscopic amplitudes predicted by such model calculations can thus be viewed as essentially “exact.” This fact, together with the availability of optical potentials for the different real and virtual channels involved in the reactions considered, namely A+2Sn+p, A+1Sn+d, and ASn+t, allows for the calculation of the associated absolute cross sections without, arguably, free parameters. The numerical predictions of the absolute differential cross sections, obtained making use of the above-mentioned nuclear structure and optical potential inputs, within the framework of second-order distorted-wave Born approximation, taking into account simultaneous, successive, and nonorthogonality contributions, provide, within experimental errors in general, and below 10% uncertainty in particular, an overall account of the experimental findings for all of the measured A+2Sn

  2. The structure of SN 1987A's outer circumstellar envelope as probed by light echoes

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin; Sugerman, Ben; Lawrence, Stephen; Kunkel, William

    2001-05-01

    We present ground-based and HST images processed by image subtraction to highlight transient reflection nebulae or ``light echoes'' of the maximum light pulse of the explosion of SN 1987A from surrounding material. Along with numerous structures already discussed elsewhere, we have found (in multiple epochs of data) a new feature opposite the SN from the mysterious ``Napoleon's Hat'' which indicates a symmetric structure due to shocks internal to the SN's red supergiant wind and probably caused by the pile-up of gas due to differential velocities within the outflow. We also show how echoes betray the ram pressure distribution of the progenitor mass loss flow. .

  3. 6+ isomers in neutron-rich Sn isotopes beyond N =82 and effective interactions

    NASA Astrophysics Data System (ADS)

    Maheshwari, Bhoomika; Jain, Ashok Kumar; Srivastava, P. C.

    2015-02-01

    Recent observation of the 6+ seniority isomers and measurements of the B (E 2 ) values in the Sn-138134 isotopes lying close to the neutron drip line have raised some questions about the validity of the currently used effective interactions in the neutron-rich region. Simpson et al. [Phys. Rev. Lett. 113, 132502 (2014), 10.1103/PhysRevLett.113.132502] had to modify the diagonal and nondiagonal ν f7/2 2 two-body matrix elements of the V l k interaction by ˜150 keV in their shell model calculations in order to explain the data of 136Sn. In contrast, we are able to explain the observed energy levels and the B (E 2 ) values after marginal reduction of the same set of matrix elements by 25 keV in the RCDB (renormalized CD-Bonn) interaction. The observed mismatch in reproducing the data of 136Sn is due to the seniority mixing. Further, we do not find it necessary to consider the core excitations, and the RCDB interaction seems better suited to explain the data beyond N =82 magic number.

  4. Visible and Near-infrared Light Curves of SN 2009nr

    NASA Astrophysics Data System (ADS)

    Heath, Jonathan; Bryngelson, Ginger

    2014-03-01

    This study explores the behavior of SN 2009nr, an apparently normal type Ia supernova (SN Ia). A plot of this object's brightness over time is known as a light curve. Because of the uniformity of their light curves, SNe Ia are valuable markers for determining the expansion of the universe and other cosmological parameters. Understanding the properties of these supernovae is vital in order to build our confidence in their use as standard candles. A small, but increasing number of SN Ia late-time observations have been made in the near-infrared (NIR). Most exhibit a flattening of the NIR power even as the visible light declines at a steady rate. It is still unclear as to why they exhibit this behavior and how typical this is. In order to characterize the late behavior of SNe Ia, images of SN 2009nr were analyzed using the Image Reduction and Analysis Facility (IRAF). NIR (J, H, K) images were taken with the 4m Mayall Telescope at Kitt Peak National-Observatory using the FLAMINGOS IR Imaging Spectrometer while visible (B, V, R, I) images used the Mosaic 1 imager. The supernova's apparent magnitude for each night of observation (by filter) was found by using reference stars. We present preliminary light curves of SN 2009nr and a comparison to another SN observed at similar epochs.

  5. Production of neutron-rich Ca, Sn, and Xe isotopes in transfer-type reactions with radioactive beams

    SciTech Connect

    Adamian, G. G.; Antonenko, N. V.; Lacroix, D.

    2010-12-15

    The production cross sections of neutron-rich isotopes {sup 52,54,56,58,60}Ca, {sup 136,138,140,142}Sn, and {sup 146,148,150,152}Xe are predicted for future experiments in the diffusive multinucleon transfer reactions {sup 86,90,92,94}Kr, {sup 124,130,132,134}Sn, {sup 136,140,142,146}Xe, and {sup 138,144,146}Ba+{sup 48}Ca with stable and radioactive beams at incident energies close to the Coulomb barrier. Because of the small cross sections, the production of neutron-rich isotopes requires the optimal choice of projectile-target combinations and bombarding energies.

  6. The light curve of SN 1987A revisited: constraining production masses of radioactive nuclides

    SciTech Connect

    Seitenzahl, Ivo R.; Timmes, F. X.; Magkotsios, Georgios

    2014-09-01

    We revisit the evidence for the contribution of the long-lived radioactive nuclides {sup 44}Ti, {sup 55}Fe, {sup 56}Co, {sup 57}Co, and {sup 60}Co to the UVOIR light curve of SN 1987A. We show that the V-band luminosity constitutes a roughly constant fraction of the bolometric luminosity between 900 and 1900 days, and we obtain an approximate bolometric light curve out to 4334 days by scaling the late time V-band data by a constant factor where no bolometric light curve data is available. Considering the five most relevant decay chains starting at {sup 44}Ti, {sup 55}Co, {sup 56}Ni, {sup 57}Ni, and {sup 60}Co, we perform a least squares fit to the constructed composite bolometric light curve. For the nickel isotopes, we obtain best fit values of M({sup 56}Ni) = (7.1 ± 0.3) × 10{sup –2} M {sub ☉} and M({sup 57}Ni) = (4.1 ± 1.8) × 10{sup –3} M {sub ☉}. Our best fit {sup 44}Ti mass is M({sup 44}Ti) = (0.55 ± 0.17) × 10{sup –4} M {sub ☉}, which is in disagreement with the much higher (3.1 ± 0.8) × 10{sup –4} M {sub ☉} recently derived from INTEGRAL observations. The associated uncertainties far exceed the best fit values for {sup 55}Co and {sup 60}Co and, as a result, we only give upper limits on the production masses of M({sup 55}Co) < 7.2 × 10{sup –3} M {sub ☉} and M({sup 60}Co) < 1.7 × 10{sup –4} M {sub ☉}. Furthermore, we find that the leptonic channels in the decay of {sup 57}Co (internal conversion and Auger electrons) are a significant contribution and constitute up to 15.5% of the total luminosity. Consideration of the kinetic energy of these electrons is essential in lowering our best fit nickel isotope production ratio to [{sup 57}Ni/{sup 56}Ni] = 2.5 ± 1.1, which is still somewhat high but is in agreement with gamma-ray observations and model predictions.

  7. Visible-light-driven photocatalytic and chemical sensing properties of SnS2 nanoflakes.

    PubMed

    Umar, Ahmad; Akhtar, M S; Dar, G N; Abaker, M; Al-Hajry, A; Baskoutas, S

    2013-09-30

    This work demonstrated the successful and facile large-scale synthesis and characterizations of SnS2 nanoflakes. The detailed morphological studies revealed that the synthesized products were nanoflakes and were grown in large quantity. The XRD pattern and detailed compositional studies confirmed that the synthesized SnS2 nanoflakes were well-crystalline and possessing hexagonal SnS2 phase. The synthesized SnS2 nanoflakes were used as efficient photocatalysts for photocatalytic degradation and effective electron mediators for the fabrication of chemical sensor. The photocatalytic properties of SnS2 nanoflakes towards the photocatalytic degradation of Rhodamine B dye under visible light irradiation showed reasonably good degradation of ~61%. Moreover, the as-synthesized SnS2 nanoflakes were used as efficient electron mediators for the fabrication of nitroaniline chemical sensor by simple I-V technique. Very high-sensitivity of ~ 505.82±0.02 mAcm(-2).(mole/L)(-1) and experimental detection limit of ~15×10(-6) (mole/L) in a short response time of ~10.0 s with LDR in the range of 15.6×10(-6)-0.5×10(-3) mole L(-1) were observed for the fabricated nitroaniline chemical sensor. The observed results indicated that the SnS2 nanoflakes can efficiently be used as visible-light-driven photocatalysts and the fabrication of ultra-high sensitive chemical sensors.

  8. Multi-Wavelength Light Curve of SN 2014G

    NASA Astrophysics Data System (ADS)

    Martin, John C.; Betzler, Alberto; Barrett, Douglas; Cason, Andy; Eenmäe, Tõnis; Kneip, Raymond; Martignoni, Massimiliano

    2014-06-01

    SN 2014G received an initial spectral classification of Type IIn (CBET 3787) as a blue continuum with some sharp emission. Later spectra (ATEL 5935) showed that it is more likely it is a Type II-L. We present multi-band photometry for this object from the peak until approximately 100 days after.

  9. Reaction dynamics of Pt* isotopes formed using stable and radioactive Sn beams

    NASA Astrophysics Data System (ADS)

    Jain, Deepika; Kumar, Raj; Sharma, Manoj K.

    2013-04-01

    The decay of various isotopes of Pt* formed using stable and neutron-rich radioactive beams of Sn is studied by using the dynamical cluster-decay model (DCM). The entrance channel effect in 190Pt* compound nuclei is investigated using different targets and projectiles. For both entrance channels, i.e., 132Sn+58Ni and 126Sn+64Ni, the fragmentation potential and preformation probability of decaying fragments are almost identical at comparable center-of-mass energies (Ec.m.), enabling us to conclude that decay of 190Pt* is independent of its formation effects. In order to check for the persistence of entrance channel independence in the decay of Pt* compound nuclei, various versions of nuclear proximity potentials and different values of level density parameter are employed in the calculations, and the results are sustained. It is also observed that, with inclusion of deformation effects up to quadrupole (β2) within the optimum orientation approach, the structure of potential energy surfaces changes significantly. Besides this, the fission mass distribution of Pt* isotopes is investigated and consequently the barrier modification is estimated to account for the phenomena of fusion hindrance. The 132Sn+58Ni reaction is also studied using four proximity potentials, i.e., Prox 1977, Prox 1988, mod-Prox 1988, and Denisov 2002 within the framework of the ℓ-summed extended-Wong model for addressing the fusion hindrance phenomena. We find that Prox 77 and Prox 88 fit the total fusion cross-section data only at above-barrier energies, whereas Denisov 2002 underestimates the data at all energies due to being least sensitive towards asymmetry and isospin. So a stronger nuclear interaction potential mod-Prox 1988 that accounts for isospin effect and asymmetry of the colliding nuclei is employed, which fits the data with smooth variation of ℓmax(Ec.m.). Our calculations indicate that the isospin and asymmetry of colliding nuclei also play an important role in the fusion

  10. Mixing of fluids in hydrothermal ore-forming (Sn,W) systems: stable isotope and rare earth elements data

    NASA Astrophysics Data System (ADS)

    Sushchevskaya, T. M.; Popova, J. A.; Velivetskaya, T. A.; Ignatiev, A. V.; Matveeva, S. S.; Limantseva, O. A.

    2012-04-01

    Experimental and physico-chemical modeling data witness to important role of mixing of different type of fluids during tin and tungsten ore formation in hydrothermal systems. Mixing of magmatogeneous fluids, exsolved from granite melts, with exogenic, initially meteoric waters in hydrothermal ore-forming systems may change chemical composition of ore-forming fluid, causing cassiterite and/or wolframite precipitation (Heinrich, 1990; Sushchevskaya, Ryzhenko, 2002). We studied the process of genetically different fluids mixing for two economic Sn-W deposits, situated in the Iultin ore region (North-East of Russia, Chukotka Penninsula). The Iultin and Svetloe deposits are located in the apical parts of close situated leucogranite stocks, formed at the final stage of the Iultin complex emplacement. Both deposits are composed of a series of quartz veins among the flyschoid rocks (T 1-2), cut by the dikes (K1) of lamprophyre, granodiorite porphyre and alpite. The veins of the deposits are dominated by the productive quartz-wolframite-cassiterite-arsenopyrite-muscovite mineral assemblage. Topaz, beryl, fluorite, and albite occur sporadically. The later sulfide (loellingite-stannite-chalcopyrite) and quartz-fluorite-calcite assemblages show insignificant development. The preore quartz veinlets in host hornfels contain disseminated iron sulfides, chalcopyrite, muscovite. Isotopic (H, O, Ar) study of minerals, supplemented by oxygen isotope data of host granites and metamorphic rocks gave us possibility to conclude, that at the Iultin and the Svetloye deposits fluid mixing was fixed on the early stages of deposit formation and could be regarded as probable cause of metal (W, Sn) precipitation. During postore time the intensive involvement of isotopically light exogenic waters have changed: a) the initial character of oxygen isotope zonality; b) the initial hydrogen isotope composition of muscovites, up to meteoric calculated values for productive fluid (while the δ18O

  11. Light stable isotope analysis of meteorites by ion microprobe

    NASA Technical Reports Server (NTRS)

    Mcsween, Harry Y., Jr.

    1994-01-01

    The main goal was to develop the necessary secondary ion mass spectrometer (SIMS) techniques to use a Cameca ims-4f ion microprobe to measure light stable isotope ratios (H, C, O and S) in situ and in non-conducting mineral phases. The intended application of these techniques was the analysis of meteorite samples, although the techniques that have been developed are equally applicable to the investigation of terrestrial samples. The first year established techniques for the analysis of O isotope ratios (delta O-18 and delta O-17) in conducting mineral phases and the measurement of S isotope ratios (delta S-34) in a variety of sulphide phases. In addition, a technique was developed to measure delta S-34 values in sulphates, which are insulators. Other research undertaken in the first year resulted in SIMS techniques for the measurement of wide variety of trace elements in carbonate minerals, with the aim of understanding the nature of alteration fluids in carbonaceous chondrites. In the second year we developed techniques for analyzing O isotope ratios in nonconducting mineral phases. These methods are potentially applicable to the measurement of other light stable isotopes such as H, C and S in insulators. Also, we have further explored the analytical techniques used for the analysis of S isotopes in sulphides by analyzing troilite in a number of L and H ordinary chondrites. This was done to see if there was any systematic differences with petrological type.

  12. ASYMMETRY IN THE OUTBURST OF SN 1987A DETECTED USING LIGHT ECHO SPECTROSCOPY

    SciTech Connect

    Sinnott, B.; Welch, D. L.; Sutherland, P. G.; Rest, A.; Bergmann, M.

    2013-04-10

    We report direct evidence for asymmetry in the early phases of SN 1987A via optical spectroscopy of five fields of its light echo system. The light echoes allow the first few hundred days of the explosion to be reobserved, with different position angles providing different viewing angles to the supernova. Light echo spectroscopy therefore allows a direct spectroscopic comparison of light originating from different regions of the photosphere during the early phases of SN 1987A. Gemini multi-object spectroscopy of the light echo fields shows fine structure in the H{alpha} line as a smooth function of position angle on the near-circular light echo rings. H{alpha} profiles originating from the northern hemisphere of SN 1987A show an excess in redshifted emission and a blue knee, while southern hemisphere profiles show an excess of blueshifted H{alpha} emission and a red knee. This fine structure is reminiscent of the 'Bochum event' originally observed for SN 1987A, but in an exaggerated form. Maximum deviation from symmetry in the H{alpha} line is observed at position angles 16 Degree-Sign and 186 Degree-Sign , consistent with the major axis of the expanding elongated ejecta. The asymmetry signature observed in the H{alpha} line smoothly diminishes as a function of viewing angle away from the poles of the elongated ejecta. We propose an asymmetric two-sided distribution of {sup 56}Ni most dominant in the southern far quadrant of SN 1987A as the most probable explanation of the observed light echo spectra. This is evidence that the asymmetry of high-velocity {sup 56}Ni in the first few hundred days after explosion is correlated to the geometry of the ejecta some 25 years later.

  13. X-Rays from the Explosion Site: Fifteen Years of Light Curves of SN 1993J

    NASA Technical Reports Server (NTRS)

    Chandra, Poonam; Dwarkadas, Vikram V.; Ray, Alak; Immler, Stefan; Pooley, David

    2009-01-01

    We present a comprehensive analysis of the X-ray light curves of SN 1993J in a nearby galaxy M81. This is the only supernova other than SN 1987A, which is so extensively followed in the X-ray bands. Here we report on SN 1993J observations with the Chandra in the year 2005 and 2008, and Swift observations in 2005, 2006 and 2008. We combined these observations with all available archival data of SN 1993J, which includes ROSAT, ASCA, Chandra, and XMM-Newton, observations from 1993 April to 2006 August. In this paper we report the X-ray light curves of SN 1993J, extending up to fifteen years, in the soft (0.3-2.4 keV), hard (2-8 keV) and combined (0.3-8 keV) bands. The hard and soft-band fluxes decline at different rates initially, but after about 5 years they both undergo a t(sup -1) decline. The soft X-rays, which are initially low, start dominating after a few hundred days. We interpret that most of the emission below 8 keV is coming from the reverse shock which is radiative initially for around first 1000-2000 days and then turn into adiabatic shock. Our hydrodynamic simulation also confirms the reverse shock origin of the observed light curves. We also compare the Ha line luminosity of SN 1993J with its X-ray light curve and note that the Ha line luminosity has a fairly high fraction of the X-ray emission, indicating presence of clumps in the emitting plasma.

  14. Thermal properties of the Tin odd isotopes 117,119,121Sn

    NASA Astrophysics Data System (ADS)

    Kadi, H.; Benhamouda, N.

    2016-07-01

    We propose to study the thermal properties of the odd isotopes of Tin: 117,119,121Sn. To this end, one used two methods to evaluate the properties of these elements. The first theoretical consideration uses a simple prescription to perform the calculation of these properties based on those of even-even neighboring isotopes, assuming the quasi-particle entropy extensivity. The even-even elements are treated as part of the Modified Lipkin-Nogami (MLN) method that allows to take into account the quantal and statistical fluctuations. The second theoretical approach consists of the generalization of the MLN formalism in the case of odd systems, by using the blocking technique. Then, this approach is applied to evaluate the thermal properties of the considered elements. The obtained results by both theoretical approaches are compared to the experimental data. The latter are deduced from the experimental level density within the canonical ensemble. It appears that the assumption of quasi-particle entropy extensivity at low excitation energy allows a simple and an effective treatment of thermal properties of odd nuclei. Indeed, this approach allows to give a good reproduction of experimental data in the particular in the region where the pairing transition occurs.

  15. Light Echoes and the Progenitor of SN 2016adj in Cen A

    NASA Astrophysics Data System (ADS)

    Sugerman, Ben; Lawrence, Stephen

    2016-02-01

    The Type Ib/IIb supernova (SN) 2016adj is the fifth closest SN to be discovered during the lifetime of HST. This event offers us a rich variety of rare and unique opportunities, including: (1) identifying the progenitor; (2) mapping the three-dimensional structure and chemical composition of the progenitor's circumstellar and the host galaxy's interstellar environments; and (3) testing models of stellar mass loss and high-mass stellar evolution. The progenitor field of the SN has been observed from the near-UV to the mid-IR with HST and Spitzer, which will immediately allow us to accomplish the first science goal by identifying the progenitor (or establishing its upper limits) once new image with the SN present are taken with both observatories. Preliminary analyses of early-time spectra of SN 2016adj indicate its light is being extinguished by at least A(V)=2-4 magnitudes, meaning it is buried deep within the dust lane of Cen A. Echoes of the SN light off of this dust will allow us to produce high-resolution, three-dimensional maps of the structure and composition of the dust in and around the line-of-sight to the SN, which we will use to accomplish science goals (2)-(3) listed above. In particular, we will directly test the hypothesis that Type Ib/IIb SNe come not from very-high mass stars but from only moderately-massive stars that lost their envelopes to close binary companions. Please note that since echoes pass through a given point in space only once, data are permanently lost for each epoch that is not observed. While we will propose for continued observations in the Cycle 13 call for proposals, most of the science we propose cannot be achieved if the observations in this proposal are not taken before Cycle 13 begins.

  16. SPECTROPOLARIMETRY OF THE TYPE Ia SN 2007sr TWO MONTHS AFTER MAXIMUM LIGHT

    SciTech Connect

    Zelaya, P.; Quinn, J. R.; Clocchiatti, A.; Baade, D.; Patat, F.; Hoeflich, P.; Maund, J.; Wang, L.; Wheeler, J. C.

    2013-02-01

    We present late-time spectropolarimetric observations of SN 2007sr, obtained with the Very Large Telescope at the ESO Paranal Observatory when the object was 63 days after maximum light. The late-time spectrum displays strong line polarization in the Ca II absorption features. SN 2007sr adds to the case of some normal Type Ia supernovae that show high line polarization or repolarization at late times, a fact that might be connected with the presence of high-velocity features at early times.

  17. Shell-model states with seniority ν =3 , 5, and 7 in odd-A neutron-rich Sn isotopes

    NASA Astrophysics Data System (ADS)

    Iskra, Ł. W.; Broda, R.; Janssens, R. V. F.; Chiara, C. J.; Carpenter, M. P.; Fornal, B.; Hoteling, N.; Kondev, F. G.; Królas, W.; Lauritsen, T.; Pawłat, T.; Seweryniak, D.; Stefanescu, I.; Walters, W. B.; Wrzesiński, J.; Zhu, S.

    2016-01-01

    Excited states with seniority ν =3 , 5, and 7 have been investigated in odd neutron-rich 119,121,123,125Sn isotopes produced by fusion-fission of 6.9-MeV/A 48Ca beams with 208Pb and 238U targets and by fission of a 238U target bombarded with 6.7-MeV/A 64Ni beams. Level schemes have been established up to high spin and excitation energies in excess of 6 MeV, based on multifold gamma-ray coincidence relationships measured with the Gammasphere array. In the analysis, the presence of isomers was exploited to identify gamma rays and propose transition placements using prompt and delayed coincidence techniques. Gamma decays of the known 27 /2- isomers were expanded by identifying new deexcitation paths feeding 23 /2+ long-lived states and 21 /2+ levels. Competing branches in the decay of 23 /2- states toward two 19 /2- levels were delineated as well. In 119Sn, a new 23 /2+ isomer was identified, while a similar 23 /2+ long-lived state, proposed earlier in 121Sn, has now been confirmed. In both cases, isomeric half-lives were determined with good precision. In the range of ν =3 excitations, the observed transitions linking the various states enabled one to propose with confidence spin-parity assignments for all the observed states. Above the 27 /2- isomers, an elaborate structure of negative-parity levels was established reaching the (39 /2- ), ν =7 states, with tentative spin-parity assignments based on the observed deexcitation paths as well as on general yrast population arguments. In all the isotopes under investigation, strongly populated sequences of positive-parity (35 /2+ ), (31 /2+ ), and (27 /2+ ) states were established, feeding the 23 /2+ isomers via cascades of three transitions. In the ,123Sn121 isotopes, these sequences also enabled the delineation of higher-lying levels, up to (43 /2+ ) states. In 123Sn, a short half-life was determined for the (35 /2+ ) state. Shell-model calculations were carried out for all the odd Sn isotopes, from 129Sn down to 119

  18. Detection of a Light Echo from the Otherwise Normal SN 2007af

    NASA Astrophysics Data System (ADS)

    Drozdov, D.; Leising, M. D.; Milne, P. A.; Pearcy, J.; Riess, A. G.; Macri, L. M.; Bryngelson, G. L.; Garnavich, P. M.

    2015-05-01

    We present the discovery of a light echo from SN 2007af, a normal Type Ia supernova (SN Ia) in NGC 5584. Hubble Space Telescope images taken three years post explosion reveal two separate echoes: an outer echo and an extended central region, which we propose to be an inner echo for which details are unresolved. Multiple images were obtained in the F160W, F350LP, F555W, and F814W using the Wide Field Camera 3. If the outer echo is produced by an interstellar dust sheet perpendicular to the line of sight, it is located ∼800 pc in front of the SN. The dust for the inner echo is 0.45 pc \\lt d\\lt 90 pc away from the SN. The inner echo color is consistent with typical interstellar dust wavelength-dependent scattering cross-sections, while the outer echo is redder than predicted. Both dust sheets, if in the foreground, are optically thin for scattering, and the outer echo sheet thickness is consistent with the inferred extinction from peak brightness. Whether the inner echo is from interstellar or circumstellar dust is ambiguous. Overall, the echo characteristics are quite similar to previously observed SN Ia echoes.

  19. Isotopic signature of atmospheric xenon released from light water reactors.

    PubMed

    Kalinowski, Martin B; Pistner, Christoph

    2006-01-01

    A global monitoring system for atmospheric xenon radioactivity is being established as part of the International Monitoring System to verify compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The isotopic activity ratios of (135)Xe, (133m)Xe, (133)Xe and (131m)Xe are of interest for distinguishing nuclear explosion sources from civilian releases. Simulations of light water reactor (LWR) fuel burn-up through three operational reactor power cycles are conducted to explore the possible xenon isotopic signature of nuclear reactor releases under different operational conditions. It is studied how ratio changes are related to various parameters including the neutron flux, uranium enrichment and fuel burn-up. Further, the impact of diffusion and mixing on the isotopic activity ratio variability are explored. The simulations are validated with reported reactor emissions. In addition, activity ratios are calculated for xenon isotopes released from nuclear explosions and these are compared to the reactor ratios in order to determine whether the discrimination of explosion releases from reactor effluents is possible based on isotopic activity ratios.

  20. ZnO:SnO nanorods and nanosheets and their enhanced photocatalytic activity under visible light irradiation

    SciTech Connect

    Harish, S. E-mail: suruponnus@gmail.com; Ponnusamy, S. E-mail: suruponnus@gmail.com; Muthamizhchelvan, C.; Silambarasan, A.; Navaneethan, M.; Archana, J.; Hayakawa, Y.

    2015-06-24

    ZnO-SnO nanocomposites were synthesized by a simple hydrothermal method. It was found that Sn concentration acted as a crucial factor in determining the morphology of ZnO-SnO nanostructures, in the presence of ethylenediamine (EDA) as a stabilizing agent. XRD analysis confirmed the formation of ZnO and SnO with good crystallinity. The morphological analysis revealed tin oxide (SnO) nanoparticles coated on the surface of ZnO nanorods and nanosheets. The photocatalytic activity of synthesized samples were evaluated by methylene blue (MB) as a model pollutant under visible light irradiation. Photocatalysis studies revealed that, ZnO-SnO nanocomposites show the enhanced photocatalytic activity compared to ZnO, which could be attributed to the formation of hetero-junction between ZnO and SnO of MB degradation. Sn concentration can extend the light absorption spectra of ZnO to visible light region and enhance the visible light photocatalytic activity. This research could provide new insights to the development of excellent photocatalyst with efficient performance for pollution control.

  1. Scattered-Light Echoes from the Historical Galactic Supernovae Cassiopeia A and Tycho (SN 1572)

    SciTech Connect

    Rest, A; Welch, D L; Suntzeff, N B; Oaster, L; Lanning, H; Olsen, K; Smith, R C; Becker, A C; Bergmann, M; Challis, P; Clocchiatti, A; Cook, K H; Damke, G; Garg, A; Huber, M E; Matheson, T; Minniti, D; Prieto, J L; Wood-Vasey, W M

    2008-05-06

    We report the discovery of an extensive system of scattered light echo arclets associated with the recent supernovae in the local neighborhood of the Milky Way: Tycho (SN 1572) and Cassiopeia A. Existing work suggests that the Tycho SN was a thermonuclear explosion while the Cas A supernova was a core collapse explosion. Precise classifications according to modern nomenclature require spectra of the outburst light. In the case of ancient SNe, this can only be done with spectroscopy of their light echo, where the discovery of the light echoes from the outburst light is the first step. Adjacent light echo positions suggest that Cas A and Tycho may share common scattering dust structures. If so, it is possible to measure precise distances between historical Galactic supernovae. On-going surveys that alert on the development of bright scattered-light echo features have the potential to reveal detailed spectroscopic information for many recent Galactic supernovae, both directly visible and obscured by dust in the Galactic plane.

  2. Low mass SN Ia and the late light curve

    SciTech Connect

    Colgate, S.A.; Fryer, C.L.; Hand, K.P.

    1995-12-31

    The late bolometric light curves of type Ia supernovae, when measured accurately over several years, show an exponential decay with a 56d half-life over a drop in luminosity of 8 magnitudes (10 half-lives). The late-time light curve is thought to be governed by the decay of Co{sup 56}, whose 77d half-life must then be modified to account for the observed decay time. Two mechanisms, both relying upon the positron fraction of the Co{sup 56} decay, have been proposed to explain this modification. One explanation requires a large amount of emission at infra-red wavelengths where it would not be detected. The other explanation has proposed a progressive transparency or leakage of the high energy positrons (Colgate, Petschek and Kriese, 1980). For the positrons to leak out of the expanding nebula at the required rate necessary to produce the modified 56d exponential, the mass of the ejecta from a one foe (10{sup 51} erg in kinetic energy) explosion must be small, M{sub ejec} = 0.4M{sub {circle_dot}} with M{sub ejec} {proportional_to} KE{sup 0.5}. Thus, in this leakage explanation, any reasonable estimate of the total energy of the explosion requires that the ejected mass be very much less than the Chandrasekhar mass of 1.4M{sub {circle_dot}}. This is very difficult to explain with the ``canonical`` Chandrasekhar-mass thermonuclear explosion that disintegrates the original white dwarf star. This result leads us to pursue alternate mechanisms of type Ia supernovae. These mechanisms include sub-Chandrasekhar thermonuclear explosions and the accretion induced collapse of Chandrasekhar mass white dwarfs. We will summarize the advantages and disadvantages of both mechanisms with considerable detail spent on our new accretion induced collapse simulations. These mechanisms lead to lower Ni{sup 56} production and hence result in type Ia supernovae with luminosities decreased down to {approximately} 50% that predicted by the ``standard`` model.

  3. Microwave assisted synthesis of porous ZnO/SnS heterojunction and its application in visible light degradation of ciprofloxacin

    NASA Astrophysics Data System (ADS)

    Makama, A. B.; Salmiaton, A.; Saion, E. B.; Choong, T. S. Y.; Abdullah, N.

    2016-07-01

    Porous ZnO/SnS heterojunctions were successfully synthesized via microwave-assisted heating of aqueous solutions containing different amounts of SnS precursors (SnCl2 and Na2S) in the presence of fixed amount of ZnCO3 nanoparticles. The experimental results revealed that the heterojunctions exhibited much higher visible light-driven photocatalytic activity for the degradation of the ciprofloxacin than pure SnS nanocrystals. The photocatalytic degradation efficiency (1-Ct/C0) of the pollutant for the most active heterogeneous nanostructure is about four times more efficient than pure SnS. The enhanced photocatalytic efficiency is ascribed to the synergic effect of high photon absorption and reduction in the recombination of electrons and holes because of efficient separation and electron transfer from the SnS to ZnO nanoparticles.

  4. Rotating Type Ia SN progenitors: explosion and light curves

    SciTech Connect

    Dominguez, I.; Piersanti, L.; Gagliardi, S.; Straniero, O.; Tornambe, A.; Bravo, E.

    2005-10-21

    High redshift SNe Ia have been recently used to calibrate the cosmological distance scale and to infer the existence of the dark energy. The reliability of such a method depends on the effective knowledge of the absolute brightness of this class of supernovae. This would require a complete understanding of the physics of SNeIa.Starting from an accreting rotating white dwarf, the only progenitor that we found to be able to grow till the Chandrasekhar mass and undergo a thermonuclear explosion, we simulate the explosion, deriving the nucleosynthesis and the light curve. We explore the final outcome in the framework of a 1D delayed detonation model, where the characteristic density for which the transition from deflagration to detonation takes place is a free parameter.Although preliminary, our results imply that rotating white dwarfs produce a range of explosive conditions, characterized by different ignition densities and total masses. Maximum luminosities of successfully explosive models differ up to 0.11 mag. In a few cases, the formation of a small highly neutronised remnant is found.

  5. Direct bandgap GeSn light emitting diodes for short-wave infrared applications grown on Si

    NASA Astrophysics Data System (ADS)

    von den Driesch, Nils; Stange, Daniela; Wirths, Stephan; Rainko, Denis; Mussler, Gregor; Stoica, Toma; Ikonic, Zoran; Hartmann, Jean-Michel; Grützmacher, Detlev; Mantl, Siegfried; Buca, Dan

    2016-03-01

    The experimental demonstration of fundamental direct bandgap, group IV GeSn alloys has constituted an important step towards realization of the last missing ingredient for electronic-photonic integrated circuits, i.e. the efficient group IV laser source. In this contribution, we present electroluminescence studies of reduced-pressure CVD grown, direct bandgap GeSn light emitting diodes (LEDs) with Sn contents up to 11 at.%. Besides homojunction GeSn LEDs, complex heterojunction structures, such as GeSn/Ge multi quantum wells (MQWs) have been studied. Structural and compositional investigations confirm high crystalline quality, abrupt interfaces and tailored strain of the grown structures. While also being suitable for light absorption applications, all devices show light emission in a narrow short-wave infrared (SWIR) range. Temperature dependent electroluminescence (EL) clearly indicates a fundamentally direct bandgap in the 11 at.% Sn sample, with room temperature emission at around 0.55 eV (2.25 µm). We have, however, identified some limitations of the GeSn/Ge MQW approach regarding emission efficiency, which can be overcome by introducing SiGeSn ternary alloys as quantum confinement barriers.

  6. Isotope effects in photo dissociation of ozone with visible light

    NASA Astrophysics Data System (ADS)

    Früchtl, Marion; Janssen, Christof; Röckmann, Thomas

    2014-05-01

    Ozone (O3) plays a key role for many chemical oxidation processes in the Earth's atmosphere. In these chemical reactions, ozone can transfer oxygen to other trace gases. This is particularly interesting, since O3 has a very peculiar isotope composition. Following the mass dependent fractionation equation δ17O = 0.52 * δ18O, most fractionation processes depend directly on mass. However, O3 shows an offset to the mass dependent fractionation line. Processes, which show such anomalies, are termed mass independent fractionations (MIF). A very well studied example for a chemical reaction that leads to mass independent fractionation is the O3 formation reaction. To what degree O3 destruction reactions need to be considered in order to understand the isotope composition of atmospheric O3 is still not fully understood and an open question within scientific community. We set up new experiments to investigate the isotope effect resulting from photo dissociation of O3 in the Chappuis band (R1). Initial O3 is produced by an electric discharge. After photolysis O3 is collected in a cold trap at the triple point temperature of nitrogen (63K). O3 is then converted to O2 in order to measure the oxygen isotopes of O3 using isotope ratio mass spectrometry. To isolate O3 photo dissociation (R1) from O3 decomposition (R2) and secondary O3 formation (R3), we use varying amounts of carbon monoxide (CO) as O atom quencher (R4). In this way we suppress the O + O3 reaction (R3) and determine the isotope fractionation in R1 and R2 separately. We present first results on the isotope effects in O3 photo dissociation with visible light in the presence of different bath gases. Results are interpreted based on chemical kinetics modeling. (R1) O3 + hυ → O (3P) + O2 (R2) O3 + O (3P) → 2 O2 (R3) O + O2 + M → O3 + M (R4) O (3P) + CO + M → CO2 + M

  7. CHANDRA OBSERVATIONS OF SN 1987A: THE SOFT X-RAY LIGHT CURVE REVISITED

    SciTech Connect

    Helder, E. A.; Broos, P. S.; Burrows, D. N.; Dewey, D.; Dwek, E.; McCray, R.; Park, S.; Racusin, J. L.; Zhekov, S. A.

    2013-02-10

    We report on the present stage of SN 1987A as observed by the Chandra X-Ray Observatory. We reanalyze published Chandra observations and add three more epochs of Chandra data to get a consistent picture of the evolution of the X-ray fluxes in several energy bands. We discuss the implications of several calibration issues for Chandra data. Using the most recent Chandra calibration files, we find that the 0.5-2.0 keV band fluxes of SN 1987A have increased by {approx}6 Multiplication-Sign 10{sup -13} erg s{sup -1} cm{sup -2} per year since 2009. This is in contrast with our previous result that the 0.5-2.0 keV light curve showed a sudden flattening in 2009. Based on our new analysis, we conclude that the forward shock is still in full interaction with the equatorial ring.

  8. Chandra Observations of SN 1987A: The Soft X-Ray Light Curve Revisited

    NASA Technical Reports Server (NTRS)

    Helder, E. A.; Broos, P. S.; Dewey, D.; Dwek, E.; McCray, R.; Park, S.; Racusin, J. L.; Zhekov, S. A.; Burrows, D. N.

    2013-01-01

    We report on the present stage of SN 1987A as observed by the Chandra X-Ray Observatory. We reanalyze published Chandra observations and add three more epochs of Chandra data to get a consistent picture of the evolution of the X-ray fluxes in several energy bands. We discuss the implications of several calibration issues for Chandra data. Using the most recent Chandra calibration files, we find that the 0.5-2.0 keV band fluxes of SN 1987A have increased by approximately 6 x 10(exp-13) erg s(exp-1)cm(exp-2) per year since 2009. This is in contrast with our previous result that the 0.5-2.0 keV light curve showed a sudden flattening in 2009. Based on our new analysis, we conclude that the forward shock is still in full interaction with the equatorial ring.

  9. Constraints on the Origin of the First Light from SN 2014J

    NASA Astrophysics Data System (ADS)

    Goobar, A.; Kromer, M.; Siverd, R.; Stassun, K. G.; Pepper, J.; Amanullah, R.; Kasliwal, M.; Sollerman, J.; Taddia, F.

    2015-01-01

    We study the very early light curve of supernova 2014J (SN 2014J) using the high-cadence broad-band imaging data obtained by the Kilodegree Extremely Little Telescope, which fortuitously observed M 82 around the time of the explosion, starting more than 2 months prior to detection, with up to 20 observations per night. These observations are complemented by observations in two narrow-band filters used in an Hα survey of nearby galaxies by the intermediate Palomar Transient Factory that also captured the first days of the brightening of the supernova. The evolution of the light curves is consistent with the expected signal from the cooling of shock heated material of large scale dimensions, gsim1R ⊙. This could be due to heated material of the progenitor, a companion star or pre-existing circumstellar environment, e.g., in the form of an accretion disk. Structure seen in the light curves during the first days after explosion could also originate from radioactive material in the outer parts of an exploding white dwarf, as suggested from the early detection of gamma-rays. The model degeneracy translates into a systematic uncertainty of ±0.3 days on the estimate of the first light from SN 2014J.

  10. Nucleon-pair states of even-even Sn isotopes based on realistic effective interactions

    NASA Astrophysics Data System (ADS)

    Cheng, Y. Y.; Qi, C.; Zhao, Y. M.; Arima, A.

    2016-08-01

    In this paper we study yrast states of 128,126,124Sn and 104,106,108Sn by using the monopole-optimized realistic interactions in terms of both the shell model (SM) and the nucleon-pair approximation (NPA). For yrast states of 128,126Sn and 104,106Sn, we calculate the overlaps between the wave functions obtained in the full SM space and those obtained in the truncated NPA space, and find that most of these overlaps are very close to 1. Very interestingly, for most of these states with positive parity and even spin or with negative parity and odd spin, the SM wave function is found to be well represented by one nucleon-pair basis state, viz., a simple picture of "nucleon-pair states" (nucleon-pair configuration without mixings) emerges. In 128,126Sn, the positive-parity (or negative-parity) yrast states with spin J >10 (or J >7 ) are found to be well described by breaking one or two S pairs in the 101+ (or 71-) state, i.e., the yrast state of seniority-two, spin-maximum, and positive-parity (or negative-parity), into non-S pair(s). Similar regularity is also pointed out for 104,106Sn. The evolution of E 2 transition rates between low-lying states in 128,126,124Sn is discussed in terms of the seniority scheme.

  11. Wave mixing in nominally undoped Sn2P2S6 at high light intensities

    NASA Astrophysics Data System (ADS)

    Shumelyuk, A.; Wesner, M.; Imlau, M.; Odoulov, S.

    2009-06-01

    The intensity dependence of the photorefractive response of Sn2P2S6 is studied for the Kr+-laser wavelength of 647 nm and pump-beam intensities of up to 10 W/cm2. A considerable enhancement of the two-beam coupling gain factor with increasing intensity at a grating spacing of ≃1 μm is attributed to a light-induced increase of the effective trap density. The large gain reached at high intensities is applied for the build up of a double phase conjugate mirror with a sub-millisecond switch-on time.

  12. Theoretical analysis on the kinetic isotope effects of bimolecular nucleophilic substitution (S(N)2) reactions and their temperature dependence.

    PubMed

    Tsai, Wan-Chen; Hu, Wei-Ping

    2013-04-23

    Factors affecting the kinetic isotope effects (KIEs) of the gas-phase S(N)2 reactions and their temperature dependence have been analyzed using the ion-molecule collision theory and the transition state theory (TST). The quantum-mechanical tunneling effects were also considered using the canonical variational theory with small curvature tunneling (CVT/SCT). We have benchmarked a few ab initio and density functional theory (DFT) methods for their performance in predicting the deuterium KIEs against eleven experimental values. The results showed that the MP2/aug-cc-pVDZ method gave the most accurate prediction overall. The slight inverse deuterium KIEs usually observed for the gas-phase S(N)2 reactions at room temperature were due to the balance of the normal rotational contribution and the significant inverse vibrational contribution. Since the vibrational contribution is a sensitive function of temperature while the rotation contribution is temperature independent, the KIEs are thus also temperature dependent. For S(N)2 reactions with appreciable barrier heights, the tunneling effects were predicted to contribute significantly both to the rate constants and to the carbon-13, and carbon-14 KIEs, which suggested important carbon atom tunneling at and below room temperature.

  13. Collectivity in the light xenon isotopes: A shell model study

    SciTech Connect

    Caurier, E.; Nowacki, F.; Sieja, K.; Poves, A.

    2010-12-15

    The lightest xenon isotopes are studied in the shell model framework, within a valence space that comprises all the orbits lying between the magic closures N=Z=50 and N=Z=82. The calculations produce collective deformed structures of triaxial nature that encompass nicely the known experimental data. Predictions are made for the (still unknown) N=Z nucleus {sup 108}Xe. The results are interpreted in terms of the competition between the quadrupole correlations enhanced by the pseudo-SU(3) structure of the positive parity orbits and the pairing correlations brought in by the 0h{sub 11/2} orbit. We also have studied the effect of the excitations from the {sup 100}Sn core on our predictions. We show that the backbending in this region is due to the alignment of two particles in the 0h{sub 11/2} orbit. In the N=Z case, one neutron and one proton align to J=11 and T=0. In {sup 110,112}Xe the alignment begins in the J=10, T=1 channel and it is dominantly of neutron-neutron type. Approaching the band termination the alignment of a neutron-proton pair to J=11 and T=0 takes over. In a more academic mood, we have studied the role of the isovector and isoscalar pairing correlations on the structure on the yrast bands of {sup 108,110}Xe and examined the possible existence of isovector and isoscalar pairing condensates in these N{approx}{approx}Z nuclei.

  14. Asymmetries in SN 2014J near Maximum Light Revealed through Spectropolarimetry

    NASA Astrophysics Data System (ADS)

    Porter, Amber L.; Leising, Mark D.; Williams, G. Grant; Milne, Peter; Smith, Paul; Smith, Nathan; Bilinski, Christopher; Hoffman, Jennifer L.; Huk, Leah; Leonard, Douglas C.

    2016-09-01

    We present spectropolarimetric observations of the nearby Type Ia supernova SN 2014J in M82 over six epochs: +0, +7, +23, +51, +77, +109, and +111 days with respect to B-band maximum. The strong continuum polarization, which is constant with time, shows a wavelength dependence unlike that produced by linear dichroism in Milky Way dust. The observed polarization may be due entirely to interstellar dust or include a circumstellar scattering component. We find that the polarization angle aligns with the magnetic field of the host galaxy, arguing for an interstellar origin. Additionally, we confirm a peak in polarization at short wavelengths that would imply {R}V\\lt 2 along the light of sight, in agreement with earlier polarization measurements. For illustrative purposes, we include a two-component fit to the continuum polarization of our +51-day epoch that combines a circumstellar scattering component with interstellar dust where scattering can account for over half of the polarization at 4000 Å. Upon removal of the interstellar polarization signal, SN 2014J exhibits very low levels of continuum polarization. Asymmetries in the distribution of elements within the ejecta are visible through moderate levels of time-variable polarization in accordance with the Si ii λ6355 absorption line. At maximum light, the line polarization reaches ˜0.6% and decreases to ˜ 0.4 % 1 week later. This feature also forms a loop on the {q}{RSP}{--}{u}{RSP} plane, illustrating that the ion does not have an axisymmetric distribution. The observed polarization properties suggest that the explosion geometry of SN 2014J is generally spheroidal with a clumpy distribution of silicon.

  15. Simultaneous Modelling of the Complete SN1993J Expansion and Radio Light Curves

    NASA Astrophysics Data System (ADS)

    Martí-Vidal, I.; Marcaide, J. M.; Alberdi, A.

    We report on our modelling of all the available VLBI data and radio light curves of supernova SN1993J. We have used the most complete expansion curve of a supernova ever, which spans more than a decade at several frequencies. For the data modelling, we have developed a new software capable of simulating the evolution of the radio emission of a supernova. We find that for explaining both the radio light curves and the expansion curve simultaneously, a radial structure of the magnetic field inside the radiating region and opacity effects from the ejected material have to be considered, together with a constant pre-supernova mass-loss rate (contrary to some results found by other authors).

  16. SN 2009ip: CONSTRAINING THE LATEST EXPLOSION PROPERTIES BY ITS LATE-PHASE LIGHT CURVE

    SciTech Connect

    Moriya, Takashi J.

    2015-04-20

    We constrain the explosion and circumstellar properties at the 2012b event of SN 2009ip based on its recently reported late-phase bolometric light curve. The explosion energy and ejected mass at the 2012b event are estimated as 0.01 M{sub ⊙} and 2 × 10{sup 49} erg, respectively. The circumstellar medium is assumed to have two components: an inner shell and an outer wind. The inner shell, which is likely created at the 2012a event, has a mass of 0.2 M{sub ⊙}. The outer wind is created by the wind mass loss before the 2012a mass ejection, and the progenitor is estimated to have had a mass-loss rate of about 0.1 M{sub ⊙} yr{sup −1} with a wind velocity of 550 km s{sup −1} before the 2012a event. The estimated explosion energy and ejected mass indicate that the 2012b event is not caused by a regular SN.

  17. Final Report on Isotope Ratio Techniques for Light Water Reactors

    SciTech Connect

    Gerlach, David C.; Gesh, Christopher J.; Hurley, David E.; Mitchell, Mark R.; Meriwether, George H.; Reid, Bruce D.

    2009-07-01

    The Isotope Ratio Method (IRM) is a technique for estimating the energy or plutonium production in a fission reactor by measuring isotope ratios in non-fuel reactor components. The isotope ratios in these components can then be directly related to the cumulative energy production with standard reactor modeling methods.

  18. Rare-isotope and kinetic studies of Pt/SnO2 catalysts

    NASA Technical Reports Server (NTRS)

    Upchurch, Billy T.; Wood, George M.; Schryer, David R.; Hess, Robert V.; Miller, Irvin M.; Kielin, Erik J.

    1990-01-01

    Closed-cycle pulsed CO2 laser operation requires the use of an efficient CO-O2 recombination catalyst for these dissociation products which otherwise would degrade the laser operation. The catalyst must not only operate at low temperatures but also must operate efficiently for long periods. In the case of the Laser Atmospheric Wind Sounder (LAWS) laser, an operational lifetime of 3 years is required. Additionally, in order to minimize atmospheric absorption and enhance aerosol scatter of laser radiation, the LAWS system will operate at 9.1 micrometers with an oxygen-18 isotope CO2 lasing medium. Consequently, the catalyst must not only operate at low temperatures but must also preserve the isotopic integrity of the rare-isotope composition in the recombination mode. Several years ago an investigation of commercially available and newly synthesized recombination catalysts for use in closed-cycle pulsed common and rare-isotope CO2 lasers was implemented at the NASA Langley Research Center. Since that time, mechanistic efforts utilizing both common and rare oxygen isotopes have been implemented and continue. Rare-isotope studies utilizing commercially available platinum-tin oxide catalyst have demonstrated that the catalyst contributes oxygen-16 to the product carbon dioxide thus rendering it unusable for rare-isotope applications. A technique has been developed for modification of the surface of the common-isotope catalyst to render it usable. Results of kinetic and isotope label studies using plug flow, recycle plug flow, and closed internal recycle plug flow reactor configuration modes are discussed.

  19. Coupled Heterojunction Sn₂Ta₂O₇@SnO₂: Cooperative Promotion of Effective Electron-Hole Separation and Superior Visible-light Absorption.

    PubMed

    Lang, Junyu; Li, Congyan; Wang, Shuwei; Lv, Juanjuan; Su, Yiguo; Wang, Xiaojing; Li, Guangshe

    2015-07-01

    In this work, a novel heterostructure integrated by two wide-band gap semiconductors, SnO2 and Sn2Ta2O7, is successfully prepared via a hydrothermal approach. Hollow Sn2Ta2O7 spheres were first formed, and small SnO2 particles were then well-dispersed onto the outside surface of the spheres, forming a p-n heterostructure. This heterostructure exhibits a higher potential edge that yielded enhanced photoredox ability. Further, the heterostructure is of Z-type with a consistent internal electric field direction, which effectively separates the photogenerated electron-hole pairs. Although both component semiconductors do not absorb visible light, the resulted p-n heterostructure is surprisingly observed to show an outstanding photocatalytic performance under visible light illumination. Such a visible light response is concluded to be the consequence of the impurity band formed by Sn(2+) doped in SnO2 and Sn(4+) in Sn2Ta2O7 via in situ redox. The existence of coupled Sn(2+) and Sn(4+) ions in p-n heterostructure is responsible for the absence of defects and the regenerated catalytic activities. The findings reported here may provide an approach to fabricate the new types of photocatalysts with a synergetic promotion for visible light absorption and sustained photocatalytic activities by coupling different wide-band semiconductors.

  20. Microwave fabrication of Cu2ZnSnS4 nanoparticle and its visible light photocatalytic properties

    PubMed Central

    2014-01-01

    Cu2ZnSnS4 nanoparticle with an average diameter of approximately 31 nm has been successfully synthesized by a time effective microwave fabrication method. The crystal structure, surface morphology, and microstructure of the Cu2ZnSnS4 nanoparticle were characterized. Moreover, the visible light photocatalytic ability of the Cu2ZnSnS4 nanoparticle toward degradation of methylene blue (MB) was also studied. About 30% of MB was degraded after 240 min irradiation when employing Cu2ZnSnS4 nanoparticle as a photocatalyst. However, almost all MB was decomposed after 90 min irradiation when introducing a small amount of H2O2 as a co-photocatalyst. The enhancement of the photocatalytic performance was attributed to the synergetic effect between the Cu2ZnSnS4 nanoparticle and H2O2. The detailed photocatalytic degradation mechanism of MB by the Cu2ZnSnS4 was further proposed. PMID:25237289

  1. Preliminary NIR Late Light Curve of the Type Ia Supernova SN2009nr

    NASA Astrophysics Data System (ADS)

    Heath, Jonathan; Bryngelson, G.

    2013-01-01

    Type Ia supernovae (SNe Ia) are important in determining the expansion of the universe based on the uniformity of their light curves. It is essential to understand the behavior of these supernovae in order to strengthen our confidence in their use as standard candles. A small, but increasing number of SNe Ia have been observed later than the 200 day epoch in the near-infrared (NIR). Most of these exhibit a flattening of the NIR power, even as the visible light declines at a steady rate. It is unclear as to exactly what causes this behavior, and how typical it is. In order to characterize the late behavior of SNe Ia, images of the supernova SN2009nr were analyzed using the Image Reduction and Analysis Facility (IRAF). These images were taken with the 4m Mayall Telescope at Kitt Peak National-Observatory using the FLAMINGOS IR Imaging Spectrometer. The supernova’s magnitude was normalized with respect to the magnitudes of known stars so that traits related to the supernova may be compared to others. We present preliminary NIR (J, H, K) light curves of the observed supernova and compare them to other SNe Ia observed at these epochs.

  2. SALT spectroscopic classification of PS16atu (SN 2016atv) as a type-Ia supernova after maximum light

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Kotze, M.

    2016-03-01

    We obtained SALT (+RSS) spectroscopy of PS16atu (SN 2016atv) on 2016 Mar 10.1 UT, covering the wavelength range 350-920 nm. Cross-correlation of the spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows PS16atu is a type-Ia supernova approximately a week past maximum light.

  3. Synthesis, characterization and photocatalytic properties of SnO2-ZnO composite under UV-A light

    NASA Astrophysics Data System (ADS)

    Kuzhalosai, V.; Subash, B.; Senthilraja, A.; Dhatshanamurthi, P.; Shanthi, M.

    2013-11-01

    The SnO2 loaded ZnO (SnO2-ZnO) was successfully synthesized by precipitation-decomposition method. The catalyst was characterized by X-ray diffraction (XRD), high resolution scanning electron microscope (HR-SEM) images, energy dispersive spectrum (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL) and BET surface area measurements. The photocatalytic activity of SnO2-ZnO was investigated for the degradation of Acid Orange 10 (AO 10) in aqueous solution using UV-A light. SnO2-ZnO is found to be more efficient than commercial ZnO, bare ZnO, TiO2-P25 and TiO2 (Merck) at pH 12 for the mineralization of AO 10 dye. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of AO 10 dye have been analyzed. The mineralization of AO 10 has been confirmed by chemical oxygen demand (COD) measurements. A degradation mechanism is proposed for the degradation of AO 10 with SnO2-ZnO under UV-A light. This catalyst is found to be reusable.

  4. THE VERY EARLY LIGHT CURVE OF SN 2015F IN NGC 2442: A POSSIBLE DETECTION OF SHOCK-HEATED COOLING EMISSION AND CONSTRAINTS ON SN Ia PROGENITOR SYSTEM

    SciTech Connect

    Im, Myungshin; Choi, Changsu; Kim, Jae-Woo; Yoon, Sung-Chul; Ehgamberdiev, Shuhrat A.; Monard, Libert A. G.; Sung, Hyun-Il E-mail: changsu@astro.snu.ac.kr

    2015-11-15

    The main progenitor candidates of Type Ia supernovae (SNe Ia) are white dwarfs in binary systems where the companion star is another white dwarf (double degenerate (DD) system) or a less-evolved, non-degenerate star with R{sub *} ≳ 0.1 R{sub ⊙} (single degenerate system). However, no direct observational evidence exists to tell us which progenitor system is more common. Recent studies suggest that the light curve of a supernova shortly after its explosion can be used to set a limit on the progenitor size, R{sub *}. Here, we report high-cadence monitoring observations of SN 2015F, a normal SN Ia in the galaxy NGC 2442, starting about 84 days before the first light time. Using our daily cadence data, we capture the emergence of the radioactively powered light curve; more importantly, with >97.4% confidence, we detect possible dim precursor emission that appears roughly 1.5 days before the rise of the radioactively powered emission. The signal is consistent with theoretical expectations for a progenitor system involving a companion star with R{sub *} ≃ 0.1–1 R{sub ⊙} or a prompt explosion of a DD system, but is inconsistent with the typically invoked size of a white dwarf progenitor of R{sub *} ∼ 0.01 R{sub ⊙}. Upper limits on the precursor emission also constrain the progenitor size to be R{sub *} ≲ 0.1 R{sub ⊙} with a companion star size of R{sub *} ≲ 1.0 R{sub ⊙}, excluding a very large companion star in the progenitor system. Additionally, we find that the distance to SN 2015F is 23.9 ± 0.4 Mpc.

  5. Near-infrared light absorption by polycrystalline SiSn alloys grown on insulating layers

    SciTech Connect

    Kurosawa, Masashi; Kato, Motohiro; Yamaha, Takashi; Taoka, Noriyuki; Nakatsuka, Osamu; Zaima, Shigeaki

    2015-04-27

    High-Sn-content SiSn alloys are strongly desired for the next-generation near-infrared optoelectronics. A polycrystalline growth study has been conducted on amorphous SiSn layers with a Sn-content of 2%–30% deposited on either a substrate of SiO{sub 2} or SiN. Incorporating 30% Sn into Si permits the crystallization of the amorphous layers at annealing temperatures below the melting point of Sn (231.9 °C). Composition analyses indicate that approximately 20% of the Sn atoms are substituted into the Si lattice after solid-phase crystallization at 150–220 °C for 5 h. Correspondingly, the optical absorption edge is red-shifted from 1.12 eV (Si) to 0.83 eV (Si{sub 1−x}Sn{sub x} (x ≈ 0.18 ± 0.04)), and the difference between the indirect and direct band gap is significantly reduced from 3.1 eV (Si) to 0.22 eV (Si{sub 1−x}Sn{sub x} (x ≈ 0.18 ± 0.04)). These results suggest that with higher substitutional Sn content the SiSn alloys could become a direct band-gap material, which would provide benefits for Si photonics.

  6. Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation.

    PubMed

    Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

    2016-01-01

    Light isotopes separation, such as (3)He/(4)He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as (3)He/(4)He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high (3)He/(4)He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application. PMID:26813491

  7. Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation

    PubMed Central

    Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

    2016-01-01

    Light isotopes separation, such as 3He/4He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as 3He/4He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high 3He/4He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application. PMID:26813491

  8. Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation

    NASA Astrophysics Data System (ADS)

    Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

    2016-01-01

    Light isotopes separation, such as 3He/4He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as 3He/4He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high 3He/4He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application.

  9. Role of Sn in the Regeneration of Pt/γ-Al2O3 Light Alkane Dehydrogenation Catalysts

    PubMed Central

    2016-01-01

    Alumina-supported Pt is one of the major industrial catalysts for light alkane dehydrogenation. This catalyst loses activity during reaction, with coke formation often considered as the reason for deactivation. As we show in this study, the amount and nature of carbon deposits do not directly correlate with the loss of activity. Rather, it is the transformation of subnanometer Pt species into larger Pt nanoparticles that appears to be responsible for the loss of catalytic activity. Surprisingly, a portion of the Sn remains atomically dispersed on the alumina surface in the spent catalyst and helps in the redispersion of the Pt. In the absence of Sn on the alumina support, the larger Pt nanoparticles formed during reaction are not redispersed during oxidative regeneration. It is known that Sn is added as a promoter in the industrial catalyst to help in achieving high propene selectivity and to minimize coke formation. This work shows that an important role of Sn is to help in the regeneration of Pt, by providing nucleation sites on the alumina surface. Aberration-corrected scanning transmission electron microscopy helps to provide unique insights into the operating characteristics of an industrially important catalyst by demonstrating the role of promoter elements, such as Sn, in the oxidative regeneration of Pt on γ-Al2O3. PMID:27076991

  10. Systematic study of GeSn heterostructure-based light-emitting diodes towards mid-infrared applications

    NASA Astrophysics Data System (ADS)

    Zhou, Yiyin; Dou, Wei; Du, Wei; Pham, Thach; Ghetmiri, Seyed Amir; Al-Kabi, Sattar; Mosleh, Aboozar; Alher, Murtadha; Margetis, Joe; Tolle, John; Sun, Greg; Soref, Richard; Li, Baohua; Mortazavi, Mansour; Naseem, Hameed; Yu, Shui-Qing

    2016-07-01

    Temperature-dependent characteristics of GeSn light-emitting diodes with Sn composition up to 9.2% have been systematically studied. Such diodes were based on Ge/GeSn/Ge double heterostructures (DHS) that were grown directly on a Si substrate via a chemical vapor deposition system. Both photoluminescence and electroluminescence spectra have been characterized at temperatures from 300 to 77 K. Based on our theoretical calculation, all GeSn alloys in this study are indirect bandgap materials. However, due to the small energy separation between direct and indirect bandgap, and the fact that radiative recombination rate greater than non-radiative, the emissions are mainly from the direct Γ-valley to valence band transitions. The electroluminescence emissions under current injection levels from 102 to 357 A/cm2 were investigated at 300 K. The monotonic increase of the integrated electroluminescence intensity was observed for each sample. Moreover, the electronic band structures of the DHS were discussed. Despite the indirect GeSn bandgap owing to the compressive strain, type-I band alignment was achieved with the barrier heights ranging from 11 to 47 meV.

  11. Relationship Between Photosynthetic Light Dosage and Metabolic Isotope Effects in the Long-term Cultured Porites Coral Skeleton

    NASA Astrophysics Data System (ADS)

    Omata, T.; Suzuki, A.; Sato, T.; Murakami, A.; Kawahata, H.; Maruyama, T.

    2008-12-01

    A long-term culture experiment of Porites spp. corals were conducted at different light dosages (light intensity, 100, 300, or 500 micro mol m-2 s-1; daily light period, 10 or 12 h) at constant temperature to examine the contribution of photosynthetic activity to skeletal carbon isotope composition. As the daily dose of photosynthetically active radiation increased, the rate of annual extension also increased. Mean isotope compositions shifted; the carbon isotope compositions became heavier and the oxygen isotope compositions became lighter at higher radiation dose. Whereas chlorophyll a (Chl a) content per both unit area and cell decreased as light dosage increased, carotenoids/Chl a increased. Skeletal oxygen isotope compositions decrease coincided with increasing skeletal growth rate, indicating the influence of so-called kinetic isotope effects. The observed carbon isotope compositions increase should be subject to both kinetic and metabolic isotope effects. Using a vector approach in the carbon-oxygen isotope compositions' plane (Omata et al., 2005), we discriminated between kinetic and metabolic isotope effects on carbon isotope compositions. The metabolic carbon isotopic fractionation-light was similar to the photosynthesis-irradiance curve, indicating the direct contribution of photosynthetic activity to metabolic isotope effects. In contrast, the fractionation of carbon isotope related to kinetic isotope effects gradually increased as the growth rate increased.

  12. Ultrahigh sensitivity and gain white light photodetector based on GaTe/Sn:CdS nanoflake/nanowire heterostructures.

    PubMed

    Zhou, Weichang; Zhou, Yong; Peng, Yuehua; Zhang, Yong; Yin, Yanling; Tang, Dongsheng

    2014-11-01

    Optoelectronic diode based on PN heterostructure is one of the most fundamental device building blocks with extensive applications. Here we reported the fabrication and optoelectronic properties of GaTe/Sn : CdS nanoflake/nanowire PN heterojunction photodetectors. With high quality contacts between metal electrodes and Sn : CdS or GaTe, the electrical measurement of GaTe/Sn : CdS hybrid heterojunction under dark condition demonstrates an excellent diode characteristic with well-defined current rectification behavior. The photocurrent increases drastically under LED white light as well as red, green, UV illumination. The on-off ratio of current is about 100 for forward bias and 3000 for reverse bias, which clearly indicates the ultrahigh sensitivity of the heterostructure photodetector to white light. The responsivity and optical gain are determined to be 607 A W(-1) and (1.06-2.16) × 10(5)%, which is higher than previous reports of single GaTe or CdS nanostructures. Combination the Ids-Vds curves under different illumination power with energy band diagrams, we assign that both the light modulation effect under forward and reverse bias and the surface molecular oxygen adsorption/desorption mechanism are dominant to the electrical transport behavior of GaTe/Sn : CdS heterojunction. This heterostructure photodetector also shows good stability and fast response speed. Both the high photosensibility and fast response time described in the present study suggest strongly that the GaTe/Sn : CdS hybrid heterostructure is a promising candidate for photodetection, optical sensing and switching devices.

  13. Observations of the light echoes from SN 1987A using the Astro-1 Ultraviolet Imaging Telescope

    NASA Technical Reports Server (NTRS)

    Crotts, Arlin P. S.; Landsman, Wayne B.; Bohlin, Ralph C.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P.

    1992-01-01

    We present the results from images taken from the region of the light echoes around SN 1987A, as acquired on the first flight of the Astro-1 Ultraviolet Imaging Telescope (UIT). They indicate a weighted-average UV echo surface brightness of about 3 x 10 exp -18 ergs/s sq cm A sq arcsec. This is consistent with earlier results obtained by the IUE when scaled by the optical surface brightness of the two different echoes observed. These results indicate that the UV flux emitted by shock from core collapse penetrating the stellar surface cannot be as strong as that predicted by a large class of theoretical models (cited herein), or that previous results on the optical scattering of echoing dust do not apply to these clouds. Prospects for a more accurate measurements once the echoes have propagated to other regions and a background measurements can be obtained with UIT are discussed. They indicate that a more accurate determination of the above results is probable with another epoch of UIT observations.

  14. Radio emission of SN1993J: the complete picture. II. Simultaneous fit of expansion and radio light curves

    NASA Astrophysics Data System (ADS)

    Martí-Vidal, I.; Marcaide, J. M.; Alberdi, A.; Guirado, J. C.; Pérez-Torres, M. A.; Ros, E.

    2011-02-01

    We report on a simultaneous modelling of the expansion and radio light curves of the supernova SN1993J. We developed a simulation code capable of generating synthetic expansion and radio light curves of supernovae by taking into consideration the evolution of the expanding shock, magnetic fields, and relativistic electrons, as well as the finite sensitivity of the interferometric arrays used in the observations. Our software successfully fits all the available radio data of SN 1993J with a standard emission model for supernovae, which is extended with some physical considerations, such as an evolution in the opacity of the ejecta material, a radial decline in the magnetic fields within the radiating region, and a changing radial density profile for the circumstellar medium starting from day 3100 after the explosion.

  15. Charge-radius change and nuclear moments in the heavy tin isotopes from laser spectroscopy: Charge radius of {sup 132}Sn

    SciTech Connect

    Le Blanc, F.; Cottereau, E.; Essabaa, S.; Obert, J.; Oms, J.; Ouchrif, A.; Roussiere, B.; Sauvage, J.; Verney, D.; Cabaret, L.; Pinard, J.; Crawford, J.E.; Lee, J.K.P.; Genevey, J.; Le Scornet, G.; Lettry, J.; Ravn, H.

    2005-09-01

    Laser spectroscopy measurements have been carried out on the neutron-rich tin isotopes with the COMPLIS experimental setup. Using the 5s{sup 2}5p{sup 23}P{sub 0}{yields}5s{sup 2}5p6s {sup 3}P{sub 1} optical transition, hyperfine spectra of {sup 126-132}Sn and {sup 125,127,129-131}Sn{sup m} were recorded for the first time. The nuclear moments and the mean square charge radius variation ({delta}) were extracted. From the quadrupole moment values, these nuclei appear to be spherical. The magnetic moments measured are thus compared with those predicted by spherical basis approaches. From the measured {delta}, the absolute charge radii of these isotopes were deduced in particular that of the doubly magic {sup 132}Sn nucleus. The comparison of the results with several mean-field-type calculations have shown that dynamical effects play an important role in the tin isotopes.

  16. SALT spectroscopic classification of PS16eho (= SN 2016gcr) as a type-Ia supernova after maximum light

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Dettman, K.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Kotze, M.

    2016-09-01

    We obtained SALT (+RSS) spectroscopy of PS16eho (= SN 2016gcr) on 2016 Sep 12.0 UT, covering the wavelength range 350-930 nm. The spectrum is significantly contaminated with host galaxy light, and we confirm the redshift of the host galaxy 2MASX J22321713-2342106 z = 0.065 (Colless et al. 2003, 2dFGRS, arXiv:astroph/0306581; via NED) with numerous absorption and emission lines.

  17. SALT spectroscopic classification of PS16efm (= SN 2016fxu) as a type-Ic supernova after maximum light

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Dettman, K.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Kotze, M.

    2016-09-01

    We obtained SALT (+RSS) spectroscopy of PS16efm (= SN 2016fxu) on 2016 Sep 8.0 UT, covering the wavelength range 350-920 nm. Cross-correlation of the spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows PS16efm is a type-Ic supernova approximately two to three weeks past maximum light.

  18. Discrimination of ginseng cultivation regions using light stable isotope analysis.

    PubMed

    Kim, Kiwook; Song, Joo-Hyun; Heo, Sang-Cheol; Lee, Jin-Hee; Jung, In-Woo; Min, Ji-Sook

    2015-10-01

    Korean ginseng is considered to be a precious health food in Asia. Today, thieves frequently compromise ginseng farms by pervasive theft. Thus, studies regarding the characteristics of ginseng according to growth region are required in order to deter ginseng thieves and prevent theft. In this study, 6 regions were selected on the basis of Korea regional criteria (si, gun, gu), and two ginseng-farms were randomly selected from each of the 6 regions. Then 4-6 samples of ginseng were acquired from each ginseng farm. The stable isotopic compositions of H, O, C, and N of the collected ginseng samples were analyzed. As a result, differences in the hydrogen isotope ratios could be used to distinguish regional differences, and differences in the nitrogen isotope ratios yielded characteristic information regarding the farms from which the samples were obtained. Thus, stable isotope values could be used to differentiate samples according to regional differences. Therefore, stable isotope analysis serves as a powerful tool to discriminate the regional origin of Korean ginseng samples from across Korea.

  19. Developing Potential New Reference Materials for Light Isotopes in Foodstuffs

    NASA Astrophysics Data System (ADS)

    Frew, Russell; Van Hale, Robert; Clarke, Dianne; Abrahim, Aiman; Resch, Christian; Mayr, Leopold; Cannavan, Andrew; Gröning, Manfred

    2013-04-01

    Measurements of subtle variations in stable isotope ratios provide the means for verifying food integrity in numerous ways. Adulterants usually have different isotopic composition so their presence in a food is readily detectable. Stable isotope measurements can also be used to determine the region of production of the food. In most cases the ability of stable isotope measurements to verify, or otherwise reject, the authenticity of the food is greatly enhanced by comparison of a result to a reference database. The more high-quality data in the database, the more statistical power is afforded by the comparison. A serious weakness at present is the lack of reference materials in food matrices available to the community. Thus researchers have to rely on in-house standards for calibration and quality assurance. The result is that there are numerous datasets published that may be internally consistent but it is exceedingly difficult to combine these datasets into a cohesive database. This is particularly important for measurements of the hydrogen isotopes. Here we present a survey of the stable isotope (^2H, ^13C and ^15N) composition of 12 Reference Materials from the International Atomic Energy Agency catalogue. All but one of these materials are plant matter and have been developed as reference materials for other applications such as radionuclide or trace element measurements. Thus they have been verified as suitable materials in terms of stability and homogeneity for those tests. The purpose of this work is to ascertain if they are similarly suitable as stable isotope reference materials. The results from our survey show that there is a wide range in elemental and isotopic composition among these materials. For example, the ^15N values range from-13.5‰ to +18.6‰ and the nitrogen elemental composition range is from 0.7% to 9.7%. The ^13C values range from -20‰ to -40‰ and the carbon elemental composition ranges from 15% to 47%. We are now in the process of

  20. THE INFRARED LIGHT CURVE OF SN 2011fe IN M101 AND THE DISTANCE TO M101

    SciTech Connect

    Matheson, T.; Joyce, R. R.; Allen, L. E.; Saha, A.; Silva, D. R.; Binkert, W. S.; Butler, K.; Everett, M.; Wood-Vasey, W. M.; Adams, J. J.; Anderson, R. E.; Beck, T. L.; Bentz, M. C.; Bershady, M. A.; Eigenbrot, A.; Gallagher, J. S.; Camarata, M. A.; Garnavich, P. M.; Glikman, E.; Harbeck, D.; and others

    2012-07-20

    We present near-infrared light curves of supernova (SN) 2011fe in M101, including 34 epochs in H band starting 14 days before maximum brightness in the B band. The light curve data were obtained with the WIYN High-Resolution Infrared Camera. When the data are calibrated using templates of other Type Ia SNe, we derive an apparent H-band magnitude at the epoch of B-band maximum of 10.85 {+-} 0.04. This implies a distance modulus for M101 that ranges from 28.86 to 29.17 mag, depending on which absolute calibration for Type Ia SNe is used.

  1. Search for light neutron-rich isotopes in stopped pion absorption

    NASA Astrophysics Data System (ADS)

    Gurov, Yu. B.; Korotkova, L. Yu.; Lapushkin, S. V.; Pritula, R. V.; Sandukovsky, V. G.; Tel'kushev, M. V.; Chernyshev, B. A.; Schurenkova, T. D.

    2016-07-01

    The results based on the spectroscopy of superheavy hydrogen isotopes (4-7H), heavy helium isotopes (6,7He), and heavy lithium isotopes (7-12Li) produced in stopped pion absorption by light nuclei were analyzed. Search for nuclear states was performed in inclusive and correlation measurements of missing mass spectra. A broad range of excitation energies studied in correlation measurements provided the possibility of search for isobaric analog states and cluster resonances. A comparison with experimental and theoretical results of other authors was conducted.

  2. Thermal treatment synthesis of SnO2 nanoparticles and investigation of its light harvesting application

    NASA Astrophysics Data System (ADS)

    Dadkhah, Mahnaz; Ansari, Fatemeh; Salavati-Niasari, Masoud

    2016-07-01

    In this research, nanostructured SnO2 materials have been prepared via thermal treatment method with the aid of new Schiff base complex. N, N'-bis(salicylidene)-1,2-propylenediamine (H2salpn) has been used as Schiff base to prepare a new Schiff base complex. The products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and TEM. Then, as-prepared SnO2 nanoparticles have been applied as working electrode in dye-sensitized solar cells sensitizing with two different natural dyes: madder and mignonette.

  3. The Mid-infrared Light Curve of Nearby Core-collapse Supernova SN 2011dh (PTF 11eon)

    NASA Astrophysics Data System (ADS)

    Helou, George; Kasliwal, Mansi M.; Ofek, Eran O.; Arcavi, Iair; Surace, Jason; Gal-Yam, Avishay

    2013-11-01

    We present Spitzer observations at 3.6 and 4.5 μm of the supernova SN 2011dh (PTF 11eon) in M51 from 18 days to 625 days after explosion. The mid-infrared emission peaks at 24 days after explosion at a few ×107 L ⊙, and decays more slowly than the visible-light bolometric luminosity. The infrared color temperature cools for the first 90 days and then is constant. Simple numerical models of a thermal echo can qualitatively reproduce the early behavior. At late times, the mid-IR light curve cannot be explained by a simple thermal echo model, suggesting additional dust heating or line emission mechanisms. We also propose that thermal echoes can serve as effective probes to uncover supernovae in heavily obscured environments, and speculate that under the right conditions, integrating the early epoch of the mid-infrared light curve may constrain the total energy in the shock breakout flash.

  4. A manual for a Laboratory Information Management System (LIMS) for light stable isotopes

    USGS Publications Warehouse

    Coplen, Tyler B.

    1998-01-01

    The reliability and accuracy of isotopic data can be improved by utilizing database software to (i) store information about samples, (ii) store the results of mass spectrometric isotope-ratio analyses of samples, (iii) calculate analytical results using standardized algorithms stored in a database, (iv) normalize stable isotopic data to international scales using isotopic reference materials, and (v) generate multi-sheet paper templates for convenient sample loading of automated mass-spectrometer sample preparation manifolds. Such a database program is presented herein. Major benefits of this system include (i) an increase in laboratory efficiency, (ii) reduction in the use of paper, (iii) reduction in workload due to the elimination or reduction of retyping of data by laboratory personnel, and (iv) decreased errors in data reported to sample submitters. Such a database provides a complete record of when and how often laboratory reference materials have been analyzed and provides a record of what correction factors have been used through time. It provides an audit trail for stable isotope laboratories. Since the original publication of the manual for LIMS for Light Stable Isotopes, the isotopes 3 H, 3 He, and 14 C, and the chlorofluorocarbons (CFCs), CFC-11, CFC-12, and CFC-113, have been added to this program.

  5. A manual for a laboratory information management system (LIMS) for light stable isotopes

    USGS Publications Warehouse

    Coplen, Tyler B.

    1997-01-01

    The reliability and accuracy of isotopic data can be improved by utilizing database software to (i) store information about samples, (ii) store the results of mass spectrometric isotope-ratio analyses of samples, (iii) calculate analytical results using standardized algorithms stored in a database, (iv) normalize stable isotopic data to international scales using isotopic reference materials, and (v) generate multi-sheet paper templates for convenient sample loading of automated mass-spectrometer sample preparation manifolds. Such a database program is presented herein. Major benefits of this system include (i) an increase in laboratory efficiency, (ii) reduction in the use of paper, (iii) reduction in workload due to the elimination or reduction of retyping of data by laboratory personnel, and (iv) decreased errors in data reported to sample submitters. Such a database provides a complete record of when and how often laboratory reference materials have been analyzed and provides a record of what correction factors have been used through time. It provides an audit trail for stable isotope laboratories. Since the original publication of the manual for LIMS for Light Stable Isotopes, the isotopes 3 H, 3 He, and 14 C, and the chlorofluorocarbons (CFCs), CFC-11, CFC-12, and CFC-113, have been added to this program.

  6. Enhancement of visible light activity in Ag modified SnO{sub 2}/TiO{sub 2}

    SciTech Connect

    Zhou, Xiufeng; Cao, Jialei; Xu, Mengfei; Wang, Zuoshan; Lu, Juan

    2013-11-15

    Graphical abstract: - Highlights: • Ag modified SnO{sub 2}/TiO{sub 2} nanoparticles were synthesized by a modified sol–gel method. • As-prepared samples have a small and uniform particle size of about 20 nm. • As-prepared samples exhibit an excellent photo-catalytic efficiency on the degradation of MB. • As-prepared samples maintain high photo-chemical stability after 5 catalytic cycles. - Abstract: Ag modified SnO{sub 2}/TiO{sub 2} nanoparticles were successfully prepared by a modified sol–gel method, without adding any acid or alkali. The entire preparation differs from the traditional sol–gel synthesis of TiO{sub 2} that the reaction can get controlled by adjusting the flow speed of water vapor. Ultraviolet–visible diffuse reflectance spectra (UV–vis) and spin-trapping electron paramagnetic resonance (EPR) were used to forecast the photocatalytic activity of the samples, and the results were proved by the degradation of methylene blue solution under visible light. Compared with pure TiO{sub 2}, as-prepared Ag modified SnO{sub 2}/TiO{sub 2} nanoparticles exhibited not only an enhanced photocatalytic activity but also an improved stability. Among all of samples, the composite with 0.5% of Ag and 1% of Sn showed the best photocatalytic performance and stability. Further increasing the Ag proportion will result in the decrease of the photocatalytic activity. A relative mechanism was proposed and discussed in detail.

  7. Effect of photosynthetic light dosage on carbon isotope composition in the coral skeleton: Long-term culture of Porites spp.

    NASA Astrophysics Data System (ADS)

    Omata, Tamano; Suzuki, Atsushi; Sato, Takanori; Minoshima, Kayo; Nomaru, Eriko; Murakami, Akio; Murayama, Shohei; Kawahata, Hodaka; Maruyama, Tadashi

    2008-06-01

    Whereas the oxygen isotope ratio of the coral skeleton is used for reconstruction of past information on seawater, the carbon isotope ratio is considered a proxy for physiological processes, principally photosynthesis and respiration. However, the fractionation of carbon isotopes in biogenic carbonate such as coral skeleton is still unclear. We conducted a long-term culture experiment of Porites spp. corals at different light dosages (light intensity, 100, 300, or 500 μmol m-2 s-1; daily light period, 10 or 12 h) at 25 ± 0.6°C to examine the contribution of photosynthetic activity to skeletal carbon isotope composition. Corals were grown in sand-filtered seawater and not fed; thus, they subsisted from photosynthesis of symbiotic algae. As the daily dose of photosynthetically active radiation increased, the rate of annual extension also increased. Mean isotope compositions shifted; the carbon isotope compositions (δ13C) became heavier and the oxygen isotope compositions (δ18O) became lighter at higher radiation dose. Skeletal δ18O decrease coincided with increasing skeletal growth rate, indicating the influence of so-called kinetic isotope effects. The observed δ13C increase should be subject to both kinetic and metabolic isotope effects, with the latter reflecting skeletal δ13C enrichment due to photosynthesis by symbiotic algae. Using a vector approach in the δ13C-δ18O plane, we discriminated between kinetic and metabolic isotope effects on δ13C. The calculated δ13C changes from metabolic isotope effects were light dose dependent. The δ13C fractionation curve related to metabolic isotope effects is very similar to the photosynthesis-irradiance curve, indicating the direct contribution of photosynthetic activity to metabolic isotope effects. In contrast, δ13C fractionation related to kinetic isotope effects gradually increased as the growth rate increased. Our experiment demonstrated that the kinetic and metabolic isotope effects in coral skeleton

  8. Ge{sub 1−x−y}Si{sub x}Sn{sub y} light emitting diodes on silicon for mid-infrared photonic applications

    SciTech Connect

    Gallagher, J. D.; Xu, C.; Menéndez, J.; Senaratne, C. L.; Wallace, P. M.; Kouvetakis, J.; Aoki, T.

    2015-10-07

    This paper reports initial the demonstration of prototype Ge{sub 1−x−y}Si{sub x}Sn{sub y} light emitting diodes with distinct direct and indirect edges and high quality I-V characteristics. The devices are fabricated on Si (100) wafers in heterostructure pin geometry [n-Ge/i-Ge{sub 1−x−y}Si{sub x}Sn{sub y}/p-Ge(Sn/Si)] using ultra low-temperature (T < 300 °C) depositions of the highly reactive chemical sources Si{sub 4}H{sub 10}, Ge{sub 4}H{sub 10}, Ge{sub 3}H{sub 8}, and SnD{sub 4}. The Sn content in the i-Ge{sub 1−x−y}Si{sub x}Sn{sub y} layer was varied from ∼3.5% to 11%, while the Si content was kept constant near 3%. The Si/Sn amounts in the p-layer were selected to mitigate the lattice mismatch so that the top interface grows defect-free, thereby reducing the deleterious effects of mismatch-induced dislocations on the optical/electrical properties. The spectral responsivity plots of the devices reveal sharp and well-defined absorption edges that systematically red-shift in the mid-IR from 1750 to 2100 nm with increasing Sn content from 3.5% to 11%. The electroluminescence spectra reveal strong direct-gap emission peaks and weak lower energy shoulders attributed to indirect gaps. Both peaks in a given spectrum red-shift with increasing Sn content and their separation decreases as the material approaches direct gap conditions in analogy with binary Ge{sub 1−y}Sn{sub y} counterparts. These findings-combined with the enhanced thermal stability of Ge{sub 1−x−y}Si{sub x}Sn{sub y} relative to Ge{sub 1−y}Sn{sub y} and the observation that ternary alloy disorder does not adversely affect the emission properties—indicate that Ge{sub 1−x−y}Si{sub x}Sn{sub y} may represent a practical target system for future generations of group-IV light sources on Si.

  9. SN 2011ht: confirming a class of interacting supernovae with plateau light curves (Type IIn-P)

    NASA Astrophysics Data System (ADS)

    Mauerhan, Jon C.; Smith, Nathan; Silverman, Jeffrey M.; Filippenko, Alexei V.; Morgan, Adam N.; Cenko, S. Bradley; Ganeshalingam, Mohan; Clubb, Kelsey I.; Bloom, Joshua S.; Matheson, Thomas; Milne, Peter

    2013-05-01

    We present photometry and spectroscopy of the Type IIn supernova (SN) 2011ht, identified previously as a possible SN impostor. The light curve exhibits an abrupt transition from a well-defined ˜120 d plateau to a steep bolometric decline, plummeting 4-5 mag in the optical and 2-3 mag in the infrared in only ˜10 d. Leading up to peak brightness (MV = -17.4 mag), a hot emission-line spectrum exhibits strong signs of interaction with circumstellar material (CSM), in the form of relatively narrow P-Cygni features of H I and He I superimposed on broad Lorentzian wings. For the latter half of the plateau phase, the spectrum exhibits strengthening P-Cygni profiles of Fe II, Ca II and Hα. By day 147, after the plateau has ended, the SN entered the nebular phase, heralded by the appearance of forbidden transitions of [O I], [O II] and [Ca II] over a weak continuum. At this stage, the light curve exhibits a low optical luminosity that is comparable to that of the most subluminous Type II-P supernovae, and a relatively fast visual wavelength decline that appeared to be significantly steeper than the 56Co decay rate. However, the total pseudo-bolometric decline, including the infrared luminosity, is consistent with 56Co decay, and implies a low 56Ni mass in the range 0.006-0.01 M⊙, near the lower end of the range exhibited by SNe II-P. We therefore characterize SN 2011ht as a core-collapse SN very similar to the peculiar SNe IIn 1994W and 2009kn. These three SNe appear to define a subclass, which are Type IIn based on their spectrum, but that also exhibit well-defined plateaus and produce low 56Ni yields. We therefore suggest Type IIn-P as a name for this subclass. The absence of observational signatures of high-velocity material from SNe IIn-P could be the result of an opaque shell at the shocked SN-CSM interface, which remains optically thick longer than the time-scale for the inner ejecta to cool and become transparent. Possible progenitors of SNe IIn-P, consistent

  10. VizieR Online Data Catalog: BVRI light curves of 3 SN (Munari+, 2013)

    NASA Astrophysics Data System (ADS)

    Munari, U.; Henden, A.; Belligoli, R.; Castellani, F.; Cherini, G.; Righetti, G. L.; Vagnozzi, A.

    2015-03-01

    BVRcIc photometry of the three program supernovae was obtained with several robotic, remotely or manually controlled telescopes operated by ANS Collaboration. Technical details of this network of telescopes running since 2005, their operational procedures and sample results are presented by Munari et al. (2012BaltA..21...13M). Detailed analysis of the photometric performances and measurements of the actual transmission profiles for all the photometric filter sets in use is presented by Munari and Moretti (2012BaltA..21...13M). Additional BVRcIc measurements of SN 2011fe and SN 2012aw were obtained at the Astrokolkhoz Observatory in New Mexico with K35, a 35cm remotely operated telescope which houses a set of Astrodon BVRcIc multi-layer dielectric filters. (4 data files).

  11. VizieR Online Data Catalog: SN 2009dc BVRI light curves (Silverman+, 2011)

    NASA Astrophysics Data System (ADS)

    Silverman, J. M.; Ganeshalingam, M.; Li, W.; Filippenko, A. V.; Miller, A. A.; Poznanski, D.

    2011-08-01

    Observations of SN 2009dc began on 2009 Apr. 17, about one week before maximum B-band brightness, in BVRI filters using the 0.76-m Katzman Automatic Imaging Telescope (KAIT) and the 1-m Nickel telescope, both at Lick Observatory. We continued to follow SN 2009dc for over 5 months until 2009 Sept. 26, when it reached the western limit of both telescopes in the early evening. We obtained late-time gVRI images of SN 2009dc using the dual-arm Low-Resolution Imaging Spectrometer (LRIS) with the 10-m Keck I telescope on 2010 Feb. 6 (281d past maximum), BRI images using the DEIMOS spectrograph (Faber et al. 2003) mounted on the 10-m Keck II telescope on 2010 Jun. 12 (403d past maximum) and V-band images again using LRIS on 2010 Jun. 13. Our optical photometry is complemented with data taken from the UltraViolet Optical Telescope (UVOT) on the Swift Observatory in the U, B, V, UVW1, UVM2 and UVW2 filters. We downloaded seven epochs of observations from the Swift archives. (2 data files).

  12. Isotope effect in the visible light photolysis of O3 and implications for the isotope effect in the O3 formation reaction

    NASA Astrophysics Data System (ADS)

    Früchtl, Marion; Janssen, Christof; Röckmann, Thomas

    2016-04-01

    The unusual isotopic composition of atmospheric O3 has been primarily attributed to a strong mass independent isotope effect in its formation reaction. We show that visible light photolysis contributes significantly to the isotope enrichment of O3 both in laboratory photolytic recycling experiments and throughout most of the troposphere. The fractionation due to photolysis is mass dependent. We also determined the (low-resolution) wavelength dependence of the fractionation associated with photolysis and find a much weaker wavelength dependence compared to semi-empirical model calculations. The fractionation in photolysis is shown not to depend on temperature, and the temperature dependent isotope enrichments found in photolysis recycling experiments can be corrected for the effect of photolysis to yield for the first time isotope effects in the O3 formation reaction only. These enrichments are then used to reassess the relative rate coefficients of several O3 - forming isotopic reaction channels.

  13. A novel method for the synthesis of BiOCl/Bi2Sn2O7 heterojunction photocatalysts with enhanced visible light photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Lv, Dongdong; Zhang, Dafeng; Sun, Qinzhao; Wu, Jiandong; Zhang, Li; Pu, Xipeng; Ma, Huiyan; Dou, Jianmin

    2016-09-01

    A novel simple method was proposed to synthesize BiOCl/Bi2Sn2O7 heterojunction photocatalysts through the treatment of Bi2Sn2O7 with HCl solution of different concentrations. The as-synthesized photocatalysts were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence, x-ray photoelectron spectroscopy and ultraviolet–visible diffuse reflectance spectroscopy. The experimental results show that sheet-like BiOCl particles were obtained after the HCl treatment. Bi2Sn2O7 nanoparticles were distributed on the BiOCl sheets, resulting in the low aggregation of the Bi2Sn2O7 nanoparticles. As compared to BiOCl and Bi2Sn2O7, BiOCl/Bi2Sn2O7 showed enhanced photocatalytic activity under visible light irradiation, which can be attributed to the effective separation of photogenerated electrons and holes due to the formation of a BiOCl/Bi2Sn2O7 heterojunction. In addition, the dominant active species and the photocatalytic mechanism were discussed in detail.

  14. A novel method for the synthesis of BiOCl/Bi2Sn2O7 heterojunction photocatalysts with enhanced visible light photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Lv, Dongdong; Zhang, Dafeng; Sun, Qinzhao; Wu, Jiandong; Zhang, Li; Pu, Xipeng; Ma, Huiyan; Dou, Jianmin

    2016-09-01

    A novel simple method was proposed to synthesize BiOCl/Bi2Sn2O7 heterojunction photocatalysts through the treatment of Bi2Sn2O7 with HCl solution of different concentrations. The as-synthesized photocatalysts were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence, x-ray photoelectron spectroscopy and ultraviolet-visible diffuse reflectance spectroscopy. The experimental results show that sheet-like BiOCl particles were obtained after the HCl treatment. Bi2Sn2O7 nanoparticles were distributed on the BiOCl sheets, resulting in the low aggregation of the Bi2Sn2O7 nanoparticles. As compared to BiOCl and Bi2Sn2O7, BiOCl/Bi2Sn2O7 showed enhanced photocatalytic activity under visible light irradiation, which can be attributed to the effective separation of photogenerated electrons and holes due to the formation of a BiOCl/Bi2Sn2O7 heterojunction. In addition, the dominant active species and the photocatalytic mechanism were discussed in detail.

  15. A novel method for the synthesis of BiOCl/Bi2Sn2O7 heterojunction photocatalysts with enhanced visible light photocatalytic properties.

    PubMed

    Lv, Dongdong; Zhang, Dafeng; Sun, Qinzhao; Wu, Jiandong; Zhang, Li; Pu, Xipeng; Ma, Huiyan; Dou, Jianmin

    2016-09-23

    A novel simple method was proposed to synthesize BiOCl/Bi2Sn2O7 heterojunction photocatalysts through the treatment of Bi2Sn2O7 with HCl solution of different concentrations. The as-synthesized photocatalysts were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence, x-ray photoelectron spectroscopy and ultraviolet-visible diffuse reflectance spectroscopy. The experimental results show that sheet-like BiOCl particles were obtained after the HCl treatment. Bi2Sn2O7 nanoparticles were distributed on the BiOCl sheets, resulting in the low aggregation of the Bi2Sn2O7 nanoparticles. As compared to BiOCl and Bi2Sn2O7, BiOCl/Bi2Sn2O7 showed enhanced photocatalytic activity under visible light irradiation, which can be attributed to the effective separation of photogenerated electrons and holes due to the formation of a BiOCl/Bi2Sn2O7 heterojunction. In addition, the dominant active species and the photocatalytic mechanism were discussed in detail. PMID:27518499

  16. A search for correlatable, isotopically light carbon and nitrogen components in lunar soils and breccias

    NASA Astrophysics Data System (ADS)

    Norris, S. J.; Swart, P. K.; Wright, I. P.; Grady, M. M.; Pillinger, C. T.

    1983-11-01

    Using stepped heating extraction techniques, determinations of carbon and nitrogen content and delta C-13 and delta N-15 values have been obtained for selected lunar soils and breccias. Only nitrogen data have been gathered for representative splits separated by size, density and magnetic properties from 12023. A plot of the total delta C-13 (after terrestrial contamination is removed) versus delta N-15 values for bulk samples reveals little evidence for a correlation between isotopically light carbon and isotopically light nitrogen of putative ancient solar wind origin. Soil 12023 is used to examine the current interpretation for the stepped release profile of nitrogen from bulk lunar samples. Mature agglutinates, postulated by previous workers to be the host of the light nitrogen, are shown to have a very constant delta N-15 value which is heavy rather than light. The actual host of the light nitrogen in 12023 has not been identified. The lowest values encountered during the study were found associated with the finest soil, but none of these was as low as for some temperature steps of the bulk soil. Interpretations regarding the origin of light nitrogen, if it is not present in agglutinates, await the results of more definitive efforts to identify the host phase.

  17. Synthesis, characterization and photocatalytic applications of N-, S-, and C-doped SnO2 nanoparticles under ultraviolet (UV) light illumination.

    PubMed

    Nouri, Azita; Fakhri, Ali

    2015-03-01

    N-, S-, and C-doped SnO2 nanoparticles were synthesized via a precipitation method and were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), Transmission Electron Microscope (TEM), UV-vis diffuse reflectance spectral (UV-vis DRS) and Brunauer-Emmett-Teller (BET) techniques. The photocatalytic activities of these SnO2 samples were investigated with methyl orange as the organic pollutant under UV light illumination. UV-vis spectroscopy demonstrated that dopants N,S,C-species can shift the absorption edge to the near UV and visible light region. N,S,C-SnO2 nanoparticles achieved the best photocatalytic efficiency and the most optimal doping ratio was 3 (T/S). The degradation of methyl orange by N,S,C-SnO2 nanoparticles fitted well with the Langmuir-Hinshelwood kinetics model. The results of subsequent experiments indicate that enhanced adsorption ability of light and high separation rate of photo induced charge carriers all play an major role in promotion of photocatalytic activity of N,S,C-SnO2 nanoparticles.

  18. Highly efficient photocatalysis of p-type Cu{sub 2}ZnSnS{sub 4} under visible-light illumination

    SciTech Connect

    Hou, Xian; Li, Yan Yan, Jian-Jun; Wang, Cheng-Wei

    2014-12-15

    Highlights: • Kesterite CZTS nanocrystal powder was synthesized by one-pot method. • First successful use CZTS nanocrystal powder as photocatalyst. • CZTS shows an efficient photocatalysis under visible light irradiation. • CZTS photocatalyst having excellent stability. - Abstract: Cu{sub 2}ZnSnS{sub 4}, as a very promising p-type semiconductor material, has been extensively used in the study of solar cells owing to its suitable band gap (1.1–1.5 eV), large absorption coefficient of 10{sup 4} cm{sup −1} in the visible spectrum, good photo stability, nontoxicity and relative abundance of the component elements. In this paper, we have successfully synthesized p-type kesterite Cu{sub 2}ZnSnS{sub 4} nanocrystal powder by facile one-pot method, and made our first successful attempt to use Cu{sub 2}ZnSnS{sub 4} nanocrystal powder as a photocatalyst to degradation methyl orange under visible-light irradiation. The exciting results show that in the visible light region, Cu{sub 2}ZnSnS{sub 4} nanocrystal powder possesses an excellent photocatalytic performance of K = 0.0317 min{sup −1}, nearly about 6 times of well known commercial P25 titania powder performance under the same conditions, which suggests that the p-type kesterite Cu{sub 2}ZnSnS{sub 4} nanocrystal would be a promising candidate of photocatalyst.

  19. Core-Shell Structural CdS@SnO₂ Nanorods with Excellent Visible-Light Photocatalytic Activity for the Selective Oxidation of Benzyl Alcohol to Benzaldehyde.

    PubMed

    Liu, Ya; Zhang, Ping; Tian, Baozhu; Zhang, Jinlong

    2015-07-01

    Core-shell structural CdS@SnO2 nanorods (NRs) were fabricated by synthesizing SnO2 nanoparticles with a solvent-assisted interfacial reaction and further anchoring them on the surface of CdS NRs under ultrasonic stirring. The morphology, composition, and microstructures of the obtained samples were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption. It was found that SnO2 nanoparticles can be tightly anchored on the surface of CdS NRs, and the thickness of SnO2 shells can be conveniently adjusted by simply changing the addition amount of SnO2 quantum dots. UV-vis diffuse reflectance spectrum indicated that SnO2 shell layer also can enhance the visible light absorption of CdS NRs to a certain extent. The results of transient photocurrents and photoluminescence spectra revealed that the core-shell structure can effectively promote the separation rate of electron-hole pairs and prolong the lifetime of electrons. Compared with the single CdS NRs, the core-shell structural CdS@SnO2 exhibited a remarkably enhanced photocatalytic activity for selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) under visible light irradiation, attributed to the more efficient separation of electrons and holes, improved surface area, and enhanced visible light absorption of core-shell structure. The radical scavenging experiments proved that in acetonitrile solution, ·O2- and holes are the main reactive species responsible for BA to BAD transformation, and the lack of ·OH radicals is favorable to obtaining high reaction selectivity.

  20. Carbon and hydrogen isotope fractionation under continuous light: implications for paleoenvironmental interpretations of the High Arctic during Paleogene warming.

    PubMed

    Yang, Hong; Pagani, Mark; Briggs, Derek E G; Equiza, M A; Jagels, Richard; Leng, Qin; Lepage, Ben A

    2009-06-01

    The effect of low intensity continuous light, e.g., in the High Arctic summer, on plant carbon and hydrogen isotope fractionations is unknown. We conducted greenhouse experiments to test the impact of light quantity and duration on both carbon and hydrogen isotope compositions of three deciduous conifers whose fossil counterparts were components of Paleogene Arctic floras: Metasequoia glyptostroboides, Taxodium distichum, and Larix laricina. We found that plant leaf bulk carbon isotopic values of the examined species were 1.75-4.63 per thousand more negative under continuous light (CL) than under diurnal light (DL). Hydrogen isotope values of leaf n-alkanes under continuous light conditions revealed a D-enriched hydrogen isotope composition of up to 40 per thousand higher than in diurnal light conditions. The isotope offsets between the two light regimes is explained by a higher ratio of intercellular to atmospheric CO(2) concentration (C (i)/C (a)) and more water loss for plants under continuous light conditions during a 24-h transpiration cycle. Apparent hydrogen isotope fractionations between source water and individual lipids (epsilon(lipid-water)) range from -62 per thousand (Metasequoia C(27) and C(29)) to -87 per thousand (Larix C(29)) in leaves under continuous light. We applied these hydrogen fractionation factors to hydrogen isotope compositions of in situ n-alkanes from well-preserved Paleogene deciduous conifer fossils from the Arctic region to estimate the deltaD value in ancient precipitation. Precipitation in the summer growing season yielded a deltaD of -186 per thousand for late Paleocene, -157 per thousand for early middle Eocene, and -182 per thousand for late middle Eocene. We propose that high-latitude summer precipitation in this region was supplemented by moisture derived from regionally recycled transpiration of the polar forests that grew during the Paleogene warming.

  1. One-step synthesis, characterization, and visible light photocatalytic activity of pure and Zn-doped SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Madhan, D.; Rajkumar, P.; Rajeshwaran, P.; Sivarajan, A.; Sangeetha, M.

    2015-08-01

    A one-step microwave irradiation route was used to synthesize undoped and Zn-doped SnO2 nanoparticles for the first time. The morphologies, structures and optical properties of the as-prepared samples were characterized by X-ray powder diffraction, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, UV-Vis spectra and photoluminescence spectra analysis. The results clearly revealed that both the pure and doped samples had a tetragonal rutile-type structure and a space group of P42/mnm have formed directly during the microwave irradiation process. FESEM studies illustrate that both the pristine and Zn-doped SnO2 form in spherical-shaped morphology with an average diameter around 41-32 nm, which is in good agreement with the average crystallite sizes calculated by Scherrer's formula. Optical studies reveal that both pristine and Zn-doped SnO2 direct transitions occur with the bandgap energies in the range of 3.43-3.26 eV. The photocatalytic activities of the pure and Zn-doped SnO2 samples were evaluated by the degradation of methylene blue rhodamine B in an aqueous solution under visible light irradiation. The photocatalytic activity and reusability of Zn (10 wt%)-doped SnO2 was much higher than that of the pure SnO2. The improvement mechanism by zinc doping was also discussed.

  2. A new era for homolytic aromatic substitution: replacing Bu3SnH with efficient light-induced chain reactions.

    PubMed

    Gurry, Michael; Aldabbagh, Fawaz

    2016-04-28

    Herein is a pertinent review of recent photochemical homolytic aromatic substitution (HAS) literature. Issues with using the reductant Bu3SnH in an oxidative process where the net loss of a hydrogen atom occurs is discussed. Nowadays more efficient light-induced chain reactions are used resulting in HAS becoming a synthetic mechanism of choice rivaling organometallic, transition-metal and electrophilic aromatic substitution protocols. The review includes aromatic substitution as part of a tandem or cascade reaction, Pschorr reaction, as well as HAS facilitated by ipso-substitution, and Smiles rearrangement. Recently visible-light photoredox catalysis, which is carried out at room temperature has become one of the most important means of aromatic substitution. The main photoredox catalysts used are polypyridine complexes of Ru(ii) and Ir(iii), although eosin Y is an alternative allowing metal-free HAS. Other radical initiator-free aromatic substitutions have used 9-mesityl-10-methylacridinium ion and N,N-bis(2,6-diisopropylphenyl)perylene-3,4,9,10-bis(dicarboximide) as the photoredox catalyst, UV-light, photoinduced electron-transfer, zwitterionic semiquinone radical anions, and Barton ester intermediates.

  3. A new era for homolytic aromatic substitution: replacing Bu3SnH with efficient light-induced chain reactions.

    PubMed

    Gurry, Michael; Aldabbagh, Fawaz

    2016-04-28

    Herein is a pertinent review of recent photochemical homolytic aromatic substitution (HAS) literature. Issues with using the reductant Bu3SnH in an oxidative process where the net loss of a hydrogen atom occurs is discussed. Nowadays more efficient light-induced chain reactions are used resulting in HAS becoming a synthetic mechanism of choice rivaling organometallic, transition-metal and electrophilic aromatic substitution protocols. The review includes aromatic substitution as part of a tandem or cascade reaction, Pschorr reaction, as well as HAS facilitated by ipso-substitution, and Smiles rearrangement. Recently visible-light photoredox catalysis, which is carried out at room temperature has become one of the most important means of aromatic substitution. The main photoredox catalysts used are polypyridine complexes of Ru(ii) and Ir(iii), although eosin Y is an alternative allowing metal-free HAS. Other radical initiator-free aromatic substitutions have used 9-mesityl-10-methylacridinium ion and N,N-bis(2,6-diisopropylphenyl)perylene-3,4,9,10-bis(dicarboximide) as the photoredox catalyst, UV-light, photoinduced electron-transfer, zwitterionic semiquinone radical anions, and Barton ester intermediates. PMID:27056571

  4. Well-crystalline porous ZnO-SnO2 nanosheets: an effective visible-light driven photocatalyst and highly sensitive smart sensor material.

    PubMed

    Lamba, Randeep; Umar, Ahmad; Mehta, S K; Kansal, Sushil Kumar

    2015-01-01

    This work demonstrates the synthesis and characterization of porous ZnO-SnO2 nanosheets prepared by the simple and facile hydrothermal method at low-temperature. The prepared nanosheets were characterized by several techniques which revealed the well-crystallinity, porous and well-defined nanosheet morphology for the prepared material. The synthesized porous ZnO-SnO2 nanosheets were used as an efficient photocatalyst for the photocatalytic degradation of highly hazardous dye, i.e., direct blue 15 (DB 15), under visible-light irradiation. The excellent photocatalytic degradation of prepared material towards DB 15 dye could be ascribed to the formation of ZnO-SnO2 heterojunction which effectively separates the photogenerated electron-hole pairs and possess high surface area. Further, the prepared porous ZnO-SnO2 nanosheets were utilized to fabricate a robust chemical sensor to detect 4-nitrophenol in aqueous medium. The fabricated sensor exhibited extremely high sensitivity of ~ 1285.76 µA/mmol L(-1)cm(-2) and an experimental detection limit of 0.078 mmol L(-1) with a linear dynamic range of 0.078-1.25 mmol L(-1). The obtained results confirmed that the prepared porous ZnO-SnO2 nanosheets are potential material for the removal of organic pollutants under visible light irradiation and efficient chemical sensing applications.

  5. Production of Light p-Process Isotopes in Neutrino-Irradiated Alpha-Rich Freezeouts

    NASA Astrophysics Data System (ADS)

    Swift, T. P.; Meyer, B. S.; The, L.-S.

    2000-12-01

    The origin of the light, neutron-capture bypassed (p-process) isotopes 92Mo, 94Mo, 96Ru, and 98Ru has long been a mystery. Sites that produce the majority of the p-process isotopes in correct solar proportions have long been known to underproduce the light species [1], thereby suggesting a different origin. The alpha-rich freezeout occurring near a nascent neutron star in Type II supernovae has been proposed [2,3,4]; however, only 92Mo is strongly produced, and it is never the most overproduced isotope, as is required for its site of origin. We explore models of alpha-rich freezeouts that include simultaneous irradiation of the nuclei by the copious neutrinos emitted during the explosion. We find that neutrino-nucleus interactions significantly enhance production of the light p-process species both by affecting the electron-nucleon ratio during the nucleosynthesis and by increasing the charge of nuclei once nuclear quasi-equilibrium clusters have broken. In many models studied, the light p-process isotopes are the most overproduced species, which supports the idea of this being a possible production site. The neutrino fluences required for light p-process isotope production are high--probably somewhat higher than current supernova models allow. Nevertheless, the results are encouraging and suggest further work is needed on this promising site. This work was supported by the NSF Research Experiences for Undergraduates (REU) Site Program through grant AST 96169939 to Florida Tech and the Southeastern Association for Research in Astronomy (SARA). It was also supported by NSF grant AST 9819877 and NASA grant NAG5-4703 at Clemson University. References: [1] Woosley, S. E., and Howard, W. M. 1978, ApJS, 36, 285 [2] Woosley, S. E., and Hoffman, R. D. 1992, ApJ, 395, 202 [3] Fuller, G. M., and Meyer, B. S. 1995, ApJ, 453, 792 [4] Hoffman, R. D., Woosley, S. E., Fuller, G. M., and Meyer, B. S. 1996, ApJ, 460, 478

  6. Late Cretaceous granites from the giant Dulong Sn-polymetallic ore district in Yunnan Province, South China: Geochronology, geochemistry, mineral chemistry and Nd-Hf isotopic compositions

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Jiang, Shao-Yong; Wang, Rong; Ma, Liang; Zhao, Kui-dong; Yan, Xiong

    2015-03-01

    As a world-class tin-tungsten province, South China is well known for its extensive Mesozoic granitic magmatism. The Dulong district, located in the western Cathaysia Block of the South China tin-tungsten province, is characterized by widespread Mesozoic granitoids and accompanying Sn-polymetallic ore deposit (~ 30 Mt of Sn). It is one of the most important polymetallic tin ore districts in China. In this study, three mineralization-related granite types were identified in the Dulong district, including the Dulong coarse-grained granite (DCG), the Dulong fine-grained granite (DFG), and the Dulong porphyritic granite (DPG). Detailed studies are presented on zircon U-Pb ages, major and trace elements, mineral chemical and Nd-Hf isotopic compositions of the tin-bearing granites from the Dulong district. LA-ICP-MS U-Pb dating of zircon grains from these three granite bodies yields ages of 90.1 ± 0.7 Ma, 89.7 ± 0.8 Ma and 86.0 ± 0.5 Ma, respectively. Geochemically, the granites are strongly peraluminous, with high contents of alkalis, enrichment in P, Li, Rb, Cs, Ta, Sn, W and U, depletion in Ti, Mg, Co, Ni, Sr, Ba, Zr, Hf, Th and rare earth elements. Fractional crystallization of plagioclase and K-feldspar was the principal process of magmatic differentiation that controlled Rb, Sr, Ba and Eu concentrations, whereas rare earth elements were fractionated by accessory minerals, such as apatite and monazite. The geochemical data suggest that the rocks are highly fractionated S-type granites. The granites show bulk rock εNd(t) values in the range of - 12.2 to - 10.8 and zircon εHf(t) values from - 15.5 to - 2.5, with Meso-Paleoproterozoic TDMC ages for both Nd and Hf isotopes. Geochemical and isotopic data suggest that these highly fractionated S-type granites DCG, DFG and DPG were originated from the same episode of partial melting of the protolith, which have analogous components of metamorphosed pelitic rocks from the Meso-Paleoproterozoic continental crust

  7. ZIRCONIUM—HAFNIUM ISOTOPE EVIDENCE FROM METEORITES FOR THE DECOUPLED SYNTHESIS OF LIGHT AND HEAVY NEUTRON-RICH NUCLEI

    SciTech Connect

    Akram, W.; Schönbächler, M.; Sprung, P.; Vogel, N.

    2013-11-10

    Recent work based on analyses of meteorite and terrestrial whole-rock samples showed that the r- and s- process isotopes of Hf were homogeneously distributed throughout the inner solar system. We report new Hf isotope data for Calcium-Aluminum-rich inclusions (CAIs) of the CV3 carbonaceous chondrite Allende, and novel high-precision Zr isotope data for these CAIs and three carbonaceous chondrites (CM, CO, CK). Our Zr data reveal enrichments in the neutron-rich isotope {sup 96}Zr (≤1ε in {sup 96}Zr/{sup 90}Zr) for bulk chondrites and CAIs (∼2ε). Potential isotope effects due to incomplete sample dissolution, galactic and cosmic ray spallation, and the nuclear field shift are assessed and excluded, leading to the conclusion that the {sup 96}Zr isotope variations are of nucleosynthetic origin. The {sup 96}Zr enrichments are coupled with {sup 50}Ti excesses suggesting that both nuclides were produced in the same astrophysical environment. The same CAIs also exhibit deficits in r-process Hf isotopes, which provides strong evidence for a decoupling between the nucleosynthetic processes that produce the light (A ≤ 130) and heavy (A > 130) neutron-rich isotopes. We propose that the light neutron-capture isotopes largely formed in Type II supernovae (SNeII) with higher mass progenitors than the supernovae that produced the heavy r-process isotopes. In the context of our model, the light isotopes (e.g. {sup 96}Zr) are predominantly synthesized via charged-particle reactions in a high entropy wind environment, in which Hf isotopes are not produced. Collectively, our data indicates that CAIs sampled an excess of materials produced in a normal mass (12-25 M{sub ☉}) SNII.

  8. Zirconium—Hafnium Isotope Evidence from Meteorites for the Decoupled Synthesis of Light and Heavy Neutron-rich Nuclei

    NASA Astrophysics Data System (ADS)

    Akram, W.; Schönbächler, M.; Sprung, P.; Vogel, N.

    2013-11-01

    Recent work based on analyses of meteorite and terrestrial whole-rock samples showed that the r- and s- process isotopes of Hf were homogeneously distributed throughout the inner solar system. We report new Hf isotope data for Calcium-Aluminum-rich inclusions (CAIs) of the CV3 carbonaceous chondrite Allende, and novel high-precision Zr isotope data for these CAIs and three carbonaceous chondrites (CM, CO, CK). Our Zr data reveal enrichments in the neutron-rich isotope 96Zr (<=1ɛ in 96Zr/90Zr) for bulk chondrites and CAIs (~2ɛ). Potential isotope effects due to incomplete sample dissolution, galactic and cosmic ray spallation, and the nuclear field shift are assessed and excluded, leading to the conclusion that the 96Zr isotope variations are of nucleosynthetic origin. The 96Zr enrichments are coupled with 50Ti excesses suggesting that both nuclides were produced in the same astrophysical environment. The same CAIs also exhibit deficits in r-process Hf isotopes, which provides strong evidence for a decoupling between the nucleosynthetic processes that produce the light (A <= 130) and heavy (A > 130) neutron-rich isotopes. We propose that the light neutron-capture isotopes largely formed in Type II supernovae (SNeII) with higher mass progenitors than the supernovae that produced the heavy r-process isotopes. In the context of our model, the light isotopes (e.g. 96Zr) are predominantly synthesized via charged-particle reactions in a high entropy wind environment, in which Hf isotopes are not produced. Collectively, our data indicates that CAIs sampled an excess of materials produced in a normal mass (12-25 M ⊙) SNII.

  9. High-spin studies and nuclear structure in three semi-magic regions of the chart: High-seniority states in Sn isotopes

    NASA Astrophysics Data System (ADS)

    Astier, Alain

    2013-12-01

    Two fusion-fission experiments have been performed and studied with the Euroball Ge array: 12C+ 238U at 90 MeV bombarding energy, and 18O + 208Pb at 85 MeV. Among the lot of new information extracted during the last decade, the latest results discussed here are the discovery of the high-spin states of 119-126Sn. The maximum value of angular momentum available in the νh11/2 shell, i.e. for mid-occupation and the breaking of the three neutron pairs (seniority v = 6), has been identified in several tin isotopes. It is the first time that such high-seniority states are established in spherical nuclei.

  10. Dynamics of laser-produced Sn microplasma for a high-brightness extreme ultraviolet light source

    SciTech Connect

    Yuspeh, S.; Tao, Y.; Burdt, R. A.; Tillack, M. S.; Ueno, Y.; Najmabadi, F.

    2011-05-16

    The effect of laser focal spot diameters of 26 and 150 {mu}m on 13.5 nm extreme ultraviolet (EUV) radiation is investigated. Simulations show that the smaller spot size has a shorter electron plasma density scale length and deeper and denser laser energy deposition region. This results in additional time required for plasma expansion and radiation transport to efficiently emit EUV light. This is experimentally observed as an increase in the delay between the EUV emission and the laser pulse. The shorter scale length plasma reabsorbs less EUV light, resulting in a higher conversion efficiency, smaller and slightly brighter light source.

  11. Isotopically Light Organic Carbon in Phanerozoic Black Shales: Diagenetic, Source, or Environmental Signal?

    NASA Astrophysics Data System (ADS)

    Meyers, P. A.

    2011-12-01

    A curious depletion of 13C in the organic matter of marine black shales has been widely recognized ever since the advent of carbon isotope measurements half a century ago. Paleozoic and Mesozoic black shales commonly have del13C values between -29 and -26 permil, whereas modern marine organic matter has values between -22 and -18 permil. The black shale values mimic those of continental organic matter, yet sedimentary settings and Rock-Eval results indicate that the organic matter is marine in origin. This presentation will overview and discuss hypotheses to explain the isotopically light values of the black shales. First, the preferential removal of isotopically heavier organic matter components such as carbohydrates by diagenesis will be examined and shown to be wanting. Second, the possible oxidation of isotopically light methane released from clathrates that would have altered the DIC pool available to phytoplankton will be considered and also be found unlikely. A third possibility - that greater concentrations of CO2 in the greenhouse atmospheres that corresponded with deposition of many black shales allowed greater discrimination against 13C during photosynthesis - will be evaluated from del13C values of bulk carbon and of algal and land-plant biomarker molecules. Finally, the possibility that stronger stratification of the surface ocean may have magnified photic zone recycling of organic matter and reincorporation of its isotopically light carbon into fresh biomass will be considered. Although the fourth possibility is contrary to the conditions of vertical mixing of nutrients that exist in modern upwelling systems and that are responsible for their high productivity, it is consistent with the strongly stratified conditions that accompanied the high productivity that produced the Pliocene-Pleistocene sapropels of the Mediterranean Sea. Because the sapropels and most Phanerozic black shales share del15N values near 0 permil, nitrogen fixation evidently was

  12. Gamma rays, X-rays, and optical light from the cobalt and the neutron star in SN 1987A

    NASA Technical Reports Server (NTRS)

    Kumagai, Shiomi; Shigeyama, Toshikazu; Nomoto, Ken'ichi; Itoh, Masayuki; Nishimura, Jun

    1989-01-01

    Recent developments in modeling the X-ray and gamma-ray emission from SN 1987A are discussed by taking into account both the decaying cobalt and the buried neutron star. The light curve and the spectra evolution of X-rays and gamma-rays are well modeled up to day of about 300 if mixing of Co-56 into hydrogen-rich envelope is assumed. However, the 16-28 keV flux observed by Ginga declines very slowly, whereas the spherical mixing model predicts that the flux should have decreased by a large factor at t greater than 300d. It is shown that this problem can be solved if the photoelectric absorption of X-rays is effectively reduced as a result of the formation of chemically inhomogeneous clumps. Based on the adopted hydrodynamical model and the abundance distribution, predictions are offered for future optical, X-ray, and gamma-ray light curves by taking into account other radioactive sources and various types of the central source, e.g., a buried neutron star accreting the reinfalling material or an isolated pulsar.

  13. Light Isotopes and Trace Organics Analysis of Mars Samples with Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Mahaffy, P.; Niemann, Hasso (Technical Monitor)

    2001-01-01

    Precision measurement of light isotopes in Mars surface minerals and comparison of this isotopic composition with atmospheric gas and other, well-mixed reservoirs such as surface dust are necessary to understand the history of atmospheric evolution from a possibly warmer and wetter Martian surface to the present state. Atmospheric sources and sinks that set these ratios are volcanism, solar wind sputtering, photochemical processes, and weathering. Measurement of a range of trace organic species with a particular focus on species such as amino acids that are the building blocks of terrestrial life are likewise important to address the questions of prebiotic and present or past biological activity on Mars. The workshop topics "isotopic mineralogy" and "biology and pre-biotic chemistry" will be addressed from the point of view of the capabilities and limitations of insitu mass spectrometry (MS) techniques such as thermally evolved gas analysis (TEGA) and gas chromatography (GC) surface experiments using MS, in both cases, as a final chemical and isotopic composition detector. Insitu experiments using straightforward adaptations of existing space proven hardware can provide a substantial improvement in the precision and accuracy of our present knowledge of isotopic composition both in molecular and atomic species in the atmosphere and those chemically bound in rocks and soils. Likewise, detection of trace organic species with greatly improved sensitivity from the Viking GCMS experiment is possible using gas enrichment techniques. The limits to precision and accuracy of presently feasible insitu techniques compared to laboratory analysis of returned samples will be explored. The insitu techniques are sufficiently powerful that they can provide a high fidelity method of screening samples obtained from a diverse set of surface locations such as the subsurface or the interior of rocks for selection of those that are the most interesting for return to Earth.

  14. Non-radiative recombination in Ge{sub 1−y}Sn{sub y} light emitting diodes: The role of strain relaxation in tuned heterostructure designs

    SciTech Connect

    Gallagher, J. D.; Xu, C.; Smith, D. J.; Menéndez, J.; Senaratne, C. L.; Sims, P.; Kouvetakis, J.; Aoki, T.

    2015-06-28

    This paper describes the properties of Ge{sub 1−y}Sn{sub y} light emitting diodes with a broad range of Sn concentrations (y = 0.0–0.11). The devices are grown upon Si(100) platforms using ultra-low temperature deposition of highly reactive Ge and Sn hydrides. The device fabrication adopts two new photodiode designs which lead to optimized performance and enables a systematic study of the effects of strain relaxation on emission efficiency. In contrast with n-Ge/i-Ge{sub 1−y}Sn{sub y}/p-Ge analogs, which in most cases contain two defected interfaces, our designs include a p-layer with composition Ge{sub 1−z}Sn{sub z} chosen to be z < y to facilitate light extraction, but with z close enough to y to guarantee no strain relaxation at the i/p interface. In addition, a Ge{sub 1−x}Sn{sub x} alloy is also used for the n layer, with compositions in the 0 ≤ x ≤ y range, so that defected and non-defected n/i interfaces can be studied. The electroluminescence spectra vs the Sn content y in the intrinsic layer of the diodes exhibit a monotonic shift in the emission wavelength from 1550 nm to 2500 nm. On the other hand, the emission intensities show a complex dependence that cannot be explained solely on the basis of Sn concentrations. Detailed theoretical modeling of these intensities makes it possible to extract recombination lifetimes that are found to be more than three times longer in samples in which strain relaxation has not occurred at the n-i interface, demonstrating the existence of a large non-radiative contribution from the relaxation defects. This finding is particularly significant for direct gap diodes with y > 0.09, for which it is practically impossible to avoid strain relaxation in n-Ge/i-Ge{sub 1−y}Sn{sub y}/p-Ge analogs. The new designs introduced here open the door to the fabrication of highly efficient electrically pumped systems for applications in future generations of integrated photonics.

  15. Excitation strengths in 109Sn: Single-neutron and collective excitations near 100Sn

    NASA Astrophysics Data System (ADS)

    DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekström, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhäuser, R.; Görgen, A.; Hess, H.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

    2012-09-01

    A set of B(E2) values for the low-lying excited states in the radioactive isotope 109Sn were deduced from a Coulomb excitation experiment. The 2.87-MeV/u radioactive beam was produced at the REX-ISOLDE facility at CERN and was incident on a secondary 58Ni target. The B(E2) values were determined using the known 2+→0+ reduced transition probability in 58Ni as normalization with the semiclassical Coulomb excitation code gosia2. The transition probabilities are compared to shell-model calculations based on a realistic nucleon-nucleon interaction and the predictions of a simple core-excitation model. This measurement represents the first determination of multiple B(E2) values in a light Sn nucleus using the Coulomb excitation technique with low-energy radioactive beams. The results provide constraints for the single-neutron states relative to 100Sn and also indicate the importance of both single-neutron and collective excitations in the light Sn isotopes.

  16. Fabrication of SnO2-Reduced Graphite Oxide Monolayer-Ordered Porous Film Gas Sensor with Tunable Sensitivity through Ultra-Violet Light Irradiation

    NASA Astrophysics Data System (ADS)

    Xu, Shipu; Sun, Fengqiang; Yang, Shumin; Pan, Zizhao; Long, Jinfeng; Gu, Fenglong

    2015-03-01

    A new graphene-based composite structure, monolayer-ordered macroporous film composed of a layer of orderly arranged macropores, was reported. As an example, SnO2-reduced graphite oxide monolayer-ordered macroporous film was fabricated on a ceramic tube substrate under the irradiation of ultra-violet light (UV), by taking the latex microsphere two-dimensional colloid crystal as a template. Graphite oxide sheets dispersed in SnSO4 aqueous solution exhibited excellent affinity with template microspheres and were in situ incorporated into the pore walls during UV-induced growth of SnO2. The growing and the as-formed SnO2, just like other photocatalytic semiconductor, could be excited to produce electrons and holes under UV irradiation. Electrons reduced GO and holes adsorbed corresponding negative ions, which changed the properties of the composite film. This film was directly used as gas-sensor and was able to display high sensitivity in detecting ethanol gas. More interestingly, on the basis of SnO2-induced photochemical behaviours, this sensor demonstrated tunable sensitivity when UV irradiation time was controlled during the fabrication process and post in water, respectively. This study provides efficient ways of conducting the in situ fabrication of a semiconductor-reduced graphite oxide film device with uniform surface structure and controllable properties.

  17. Fabrication of SnO₂-reduced graphite oxide monolayer-ordered porous film gas sensor with tunable sensitivity through ultra-violet light irradiation.

    PubMed

    Xu, Shipu; Sun, Fengqiang; Yang, Shumin; Pan, Zizhao; Long, Jinfeng; Gu, Fenglong

    2015-01-01

    A new graphene-based composite structure, monolayer-ordered macroporous film composed of a layer of orderly arranged macropores, was reported. As an example, SnO2-reduced graphite oxide monolayer-ordered macroporous film was fabricated on a ceramic tube substrate under the irradiation of ultra-violet light (UV), by taking the latex microsphere two-dimensional colloid crystal as a template. Graphite oxide sheets dispersed in SnSO4 aqueous solution exhibited excellent affinity with template microspheres and were in situ incorporated into the pore walls during UV-induced growth of SnO2. The growing and the as-formed SnO2, just like other photocatalytic semiconductor, could be excited to produce electrons and holes under UV irradiation. Electrons reduced GO and holes adsorbed corresponding negative ions, which changed the properties of the composite film. This film was directly used as gas-sensor and was able to display high sensitivity in detecting ethanol gas. More interestingly, on the basis of SnO2-induced photochemical behaviours, this sensor demonstrated tunable sensitivity when UV irradiation time was controlled during the fabrication process and post in water, respectively. This study provides efficient ways of conducting the in situ fabrication of a semiconductor-reduced graphite oxide film device with uniform surface structure and controllable properties. PMID:25758292

  18. Facile fabrication of p-BiOI/n-Zn{sub 2}SnO{sub 4} heterostructures with highly enhanced visible light photocatalytic performances

    SciTech Connect

    Li, Houran; Jin, Zhao; Sun, Honggang; Sun, Liming; Li, Qingbo; Zhao, Xian; Jia, Chun-Jiang; Fan, Weiliu

    2014-07-01

    Highlights: • The BiOI/Zn{sub 2}SnO{sub 4} photocatalysts were prepared by a mild wet chemical method. • The ZB-1/2 (Zn to Bi molar ratio = 1/2) exhibits the best photocatalytic activity. • The enhanced performance results from high separation of photogenerated carriers. - Abstract: New BiOI/Zn{sub 2}SnO{sub 4} p–n heterojunction photocatalysts were prepared by anchoring n-type Zn{sub 2}SnO{sub 4} nanoparticles on p-type BiOI plates. The physicochemical characteristics of the catalysts were studied by X-ray powder diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Ultraviolet visible (UV–vis) diffuse reflectance spectroscopy (DRS), nitrogen adsorption–desorption, and photoelectrochemistry measurement. The as-prepared catalysts exhibited excellent photocatalytic activity for the decomposition of methyl orange (MO) under visible light irradiation. The enhanced photocatalytic performance of BiOI/Zn{sub 2}SnO{sub 4} was not only attributed to the matched band potentials but also the interconnected heterojunction of BiOI and Zn{sub 2}SnO{sub 4} nanoparticles.

  19. Origin of the granites and related Sn and Pb-Zn polymetallic ore deposits in the Pengshan district, Jiangxi Province, South China: constraints from geochronology, geochemistry, mineral chemistry, and Sr-Nd-Hf-Pb-S isotopes

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Jiang, Shao-Yong; Luo, Lan; Zhao, Kui-Dong; Ma, Liang

    2016-05-01

    The Pengshan Sn and Pb-Zn polymetallic deposits are located in the south margin of the Jiujiang-Ruichang (Jiurui) district of the Middle-Lower Yangtze River Metallogenic Belt in South China. Four large deposits include Huangjinwa, Zengjialong, Jianfengpo, and Zhangshiba, the former three are Sn-dominant deposits which occur as stratiform orebodies in the contact zones of the Pengshan granites and within the country rock strata, whereas Zhangshiba consists of stratiform Pb-Zn orebodies within the Precambrian metasedimentary strata. In this study, we present results on zircon U-Pb ages, major and trace elements, and mineral chemistry as well as Sr-Nd-Hf isotope data of the granites, Pb and S isotopes of both the Sn-dominant and Pb-Zn dominant deposits, and U-Pb dating of cassiterite from the Pengshan district. SHRIMP and LA-ICP-MS zircon U-Pb dating shows that the Pengshan granites were emplaced in the Early Cretaceous (129-128 Ma), which is in good agreement with the U-Pb dating (130-128 Ma) of cassiterite from the Jianfengpo Sn deposit. The Pengshan granites consist mainly of weakly peraluminous highly fractionated I-type affinity granitic rocks. Detailed elemental and isotopic data suggest that the granites formed by partial melting of Mesoproterozoic metamorphic basement materials with minor input of mantle-derived melts. The mineral chemistry of biotite demonstrates that the Pengshan granitic magma had a low oxygen fugacity, thereby precluding the tin dominantly partitioning into the rock-forming silicate minerals and favoring accumulation in the exsolved residual liquid during magma crystallization stages. Sulfur isotopes show a relatively heavy sulfur isotopic composition from 5.8 to 17.6 ‰, and no difference for sulfur isotopes between the Sn deposits (5.8-13.4 ‰, Huangjinwa, Zengjialong, Jianfengpo) and the Pb-Zn deposit (mostly 7.1-13.0 ‰, except for one 17.6 ‰, Zhangshiba). The sulfur isotope data of pyrite from the host sedimentary rocks show

  20. METHOD OF AND APPARATUS FOR WITHDRAWING LIGHT ISOTOPIC PRODUCT FROM A LIQUID THERMAL DIFFUSION PLANT

    DOEpatents

    Dole, M.

    1959-09-22

    An improved process and apparatus are described for removing enriched product from the columns of a thermal diffusion plant for separation of isotopes. In the removal cycle, light product at the top cf the diffusion columns is circulated through the column tops and a shipping cylinder connected thereto unttl the concertation of enriched product in the cylinder reaches the desired point. During the removal, circulation through the bottoms is blocked bv freezing. in the diffusion cycle, the bottom portion is unfrozen, fresh feed is distributed to the bottoms of the columns, ard heavy product is withdrawn from the bottoms, while the tops of the columns are blocked by freezing.

  1. White-light luminescence properties of Mg and Sn doped ZnO prepared by thermal oxidation

    SciTech Connect

    Zeng, Jun; Fan, Huiqing; Xue, Jun; Wang, Yangli

    2014-02-01

    Graphical abstract: The PL spectrum of MgSnZnO was measured at room temperature through multi-peak Gaussian fitting, it is found that the broad emission is composed of six peaks. - Highlights: • Mg and Sn doped ZnO are synthesized by thermal oxidation of MgSnZn alloys. • The structure is characterized by XRD and micro-Raman scattering technology. • The optical properties are characterized by photoluminescence spectrum. • The resulting Mg and Sn doped ZnO shows white photoluminescence. - Abstract: This work reports that Mg and Sn doped ZnO (MgSnZnO) are synthesized by thermal oxidation of MgSnZn alloys. The structure and optical properties are characterized by X-ray diffraction (XRD), micro-Raman scattering technology and photoluminescence spectrum. Interestingly, the resulting MgSnZnO shows white photoluminescence. Additionally, the photoluminescence spectrum of MgSnZnO shows two broad emission bands ranging from 360 to 420 nm and 420 to 630 nm, respectively. Through multi-peak Gaussian fitting, it is found that the broad emission is composed of six Gaussian peaks. The six Gaussian peaks are centrered at 383 nm, 397 nm, 455 nm, 516 nm, 560 nm and 614 nm.

  2. Synthesis, features and solar-light-driven photocatalytic activity of TiO2 nanotube arrays loaded with SnO2.

    PubMed

    Sim, Lan Ching; Ng, Kai Wern; Ibrahim, Shaliza; Saravanan, Pichiah

    2014-09-01

    In the present study TiO2 nanotube arrays (TNTs) were loaded with a post-transition metal oxide particles namely SnO2 via incipient wet impregnation method by varying its concentration (1.59 wt%, 2.25 wt% and 2.84 wt%). The photocatalytic activity of the prepared photocatalyst was evaluated for the degradation of methylene blue (MB) in presence of natural solar light irradiation. The morphological analyses revealed that the prepared TNTs had average inner diameter of 109 nm, wall thickness of 15 nm and tube length of 7-10 μm, respectively, while the crystalline phase and Raman spectra confirmed the 100% anatase mineral form of TiO2. Further, the presence of SnO2 in TNTs was confirmed by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The visible light absorption properties of TNTs improved drastically with increasing SnO2 loadings. The coupling effect of SnO2 and TiO2 significantly enhanced degradation efficiency of MB. An 84% degradation of MB was achieved in 6 h of irradiation under clear sky condition. PMID:25924362

  3. Shell-model states with seniority ν=3 , 5, and 7 in odd- A neutron-rich Sn isotopes

    SciTech Connect

    Iskra, Ł. W.; Broda, R.; Janssens, R. V. F.; Chiara, C. J.; Carpenter, M. P.; Fornal, B.; Hoteling, N.; Kondev, F. G.; Królas, W.; Lauritsen, T.; Pawłat, T.; Seweryniak, D.; Stefanescu, I.; Walters, W. B.; Wrzesiński, J.; Zhu, S.

    2016-01-01

    Excited states with seniority ν=3, 5, and 7 have been investigated in odd neutron-rich Sn119,121,123,125 isotopes produced by fusion-fission of 6.9-MeV/ACa48 beams with Pb208 and U238 targets and by fission of a U238 target bombarded with 6.7-MeV/ANi64 beams. Level schemes have been established up to high spin and excitation energies in excess of 6 MeV, based on multifold gamma-ray coincidence relationships measured with the Gammasphere array. In the analysis, the presence of isomers was exploited to identify gamma rays and propose transition placements using prompt and delayed coincidence techniques. Gamma decays of the known 27/2- isomers were expanded by identifying new deexcitation paths feeding 23/2+ long-lived states and 21/2+ levels. Competing branches in the decay of 23/2- states toward two 19/2- levels were delineated as well. In Sn119, a new 23/2+ isomer was identified, while a similar 23/2+ long-lived state, proposed earlier in Sn121, has now been confirmed. In both cases, isomeric half-lives were determined with good precision. In the range of ν=3 excitations, the observed transitions linking the various states enabled one to propose with confidence spin-parity assignments for all the observed states. Above the 27/2- isomers, an elaborate structure of negative-parity levels was established reaching the (39/2-), ν=7 states, with tentative spin-parity assignments based on the observed deexcitation paths as well as on general yrast population arguments. In all the isotopes under investigation, strongly populated sequences of positive-parity (35/2+), (31/2+), and (27/2+) states were established, feeding the 23/2+ isomers via cascades of three transitions. In the Sn121,123 isotopes, these sequences also enabled the delineation of higher-lying levels, up to (43/2+) states. In Sn123, a short half-life was determined for the (35/2+) state. Shell-model calculations were carried out for all the odd Sn isotopes, from Sn129 down to Sn119, and the results were

  4. SALT spectroscopic classification of LSQ16acz (= PS16bby = SN 2016bew) as a type-Ia supernova approaching maximum light

    NASA Astrophysics Data System (ADS)

    Jha, S. W.; Pan, Y.-C.; Foley, R. J.; Rest, A.; Scolnic, D.; Kotze, M.

    2016-03-01

    We obtained SALT (+RSS) spectroscopy of LSQ16acz (= PS16bby = SN 2016bew; Baltay et al. 2013, PASP, 125, 683) on 2016 Mar 14.9 UT, covering the wavelength range 340-920 nm. Cross-correlation of the spectrum with a template library using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows LSQ16acz is a type-Ia supernova a few days before maximum light.

  5. Production of medical isotopes from a thorium target irradiated by light charged particles up to 70 MeV

    NASA Astrophysics Data System (ADS)

    Duchemin, C.; Guertin, A.; Haddad, F.; Michel, N.; Métivier, V.

    2015-02-01

    The irradiation of a thorium target by light charged particles (protons and deuterons) leads to the production of several isotopes of medical interest. Direct nuclear reaction allows the production of Protactinium-230 which decays to Uranium-230 the mother nucleus of Thorium-226, a promising isotope for alpha radionuclide therapy. The fission of Thorium-232 produces fragments of interest like Molybdenum-99, Iodine-131 and Cadmium-115g. We focus our study on the production of these isotopes, performing new cross section measurements and calculating production yields. Our new sets of data are compared with the literature and the last version of the TALYS code.

  6. Production of medical isotopes from a thorium target irradiated by light charged particles up to 70 MeV.

    PubMed

    Duchemin, C; Guertin, A; Haddad, F; Michel, N; Métivier, V

    2015-02-01

    The irradiation of a thorium target by light charged particles (protons and deuterons) leads to the production of several isotopes of medical interest. Direct nuclear reaction allows the production of Protactinium-230 which decays to Uranium-230 the mother nucleus of Thorium-226, a promising isotope for alpha radionuclide therapy. The fission of Thorium-232 produces fragments of interest like Molybdenum-99, Iodine-131 and Cadmium-115g. We focus our study on the production of these isotopes, performing new cross section measurements and calculating production yields. Our new sets of data are compared with the literature and the last version of the TALYS code.

  7. Production of medical isotopes from a thorium target irradiated by light charged particles up to 70 MeV.

    PubMed

    Duchemin, C; Guertin, A; Haddad, F; Michel, N; Métivier, V

    2015-02-01

    The irradiation of a thorium target by light charged particles (protons and deuterons) leads to the production of several isotopes of medical interest. Direct nuclear reaction allows the production of Protactinium-230 which decays to Uranium-230 the mother nucleus of Thorium-226, a promising isotope for alpha radionuclide therapy. The fission of Thorium-232 produces fragments of interest like Molybdenum-99, Iodine-131 and Cadmium-115g. We focus our study on the production of these isotopes, performing new cross section measurements and calculating production yields. Our new sets of data are compared with the literature and the last version of the TALYS code. PMID:25574934

  8. Selected isotope ratio measurements of light metallic elements (Li, Mg, Ca, and Cu) by multiple collector ICP-MS

    PubMed Central

    Platzner, Thomas I.; Segal, Irina

    2007-01-01

    The unique capabilities of multiple collector inductively coupled mass spectrometry (MC-ICP-MS) for high precision isotope ratio measurements in light elements as Li, Mg, Ca, and Cu are reviewed in this paper. These elements have been intensively studied at the Geological Survey of Israel (GSI) and other laboratories over the past few years, and the methods used to obtain high precision isotope analyses are discussed in detail. The scientific study of isotopic fractionation of these elements is significant for achieving a better understanding of geochemical and biochemical processes in nature and the environment. PMID:17962922

  9. Magmatic nature of Sn-bearing fluids from isotopic (H,O) data of tourmalines (Solnechnoye deposit, Far East of Russia)

    NASA Astrophysics Data System (ADS)

    Sushchevskaya, Tatiana; Ignatiev, Alexander; Velivetskaya, Tatiana

    2010-05-01

    It was shown, that the main factors, controlled Sn-W ore deposition in hydrothermal systems in connection with granites were: a) cooling, b) mixing of fluids of different composition and genesis, c) heterogenization (boiling) of mineral forming fluids (Heinrich, 1990; et al). The results of physical chemical modelling of water-rock interaction pointed to magmatic nature of tin-bearing fluids in the hydrothermal systems, connected with granites. Tin concentration in model magmatogeneous fluid was calculated to be three times higher than in the model exogenic fluid (Sushchevskaya, Ryzhenko, 1998). New data on the source of ore forming fluids, which had formed the large economic Solnechnoye Sn deposit (Far East of Russia), were obtained from hydrogen and oxygen isotopic composition of tourmalines from successive mineral associations. Hydrogen position in the tourmaline crystal structure allows to suppose, that postproductive processes did not change the initial δD values, in contrast to phyllosilicates, often used for this purpose. During mineral formation at the Solnechnoye deposit tourmaline was formed practically without interruption. Its composition was gradually changed from schorl to dravite, when temperature decreased. The ores of cassiterite-tourmaline type were formed in a vertically dipping fracture zones, extended in a metamorphosed sandstone-shale rocks. Hydrogene and oxygen isotopic composition of fluids were calculated from tourmaline data with the help of equations, proposed in (Kotzer et al., 1993). The temperature intervals for these calculations were accepted as: 1- 450-400o C for quartz-tourmaline preore stage, 2 - 400-350o C -for early productive quartz-cassiterite stage, 3 - 350-300o C - for late quartz- cassiterite stage. The obtained results corresponded to magmatic character of the fluids of productive stage of the Solnechnoye deposit, because their isotopic composition lied in the interval: δ18О (3.2-9.3)‰, δD -(31.7-76.6)‰. The

  10. Vibrational spectra of chemical and isotopic variants of oxyluciferin, the light emitter of firefly bioluminescence.

    PubMed

    Maltsev, Oleg V; Yue, Ling; Rebarz, Mateusz; Hintermann, Lukas; Sliwa, Michel; Ruckebusch, Cyril; Pejov, Ljupčo; Liu, Ya-Jun; Naumov, Panče

    2014-08-18

    The chemical complexity of oxyluciferin (OxyLH2), the light-emitting molecule in the bioluminescence of fireflies, originates from the possibility of keto/enol tautomerism and single or double deprotonation. Herein, we present detailed infrared spectroscopic analysis of OxyLH2 and several of its chemical isomers and isotopomers. To facilitate the future characterization of its biogenic forms, we provide accurate assignments of the solid-state and solution FTIR spectra of OxyLH2 based on comparison to six isotopically labeled variants ([2-(13)C]-OxyLH2, [3-(15)N]-OxyLH2, [4-(13)C]-OxyLH2, [5-(13)C]-OxyLH2, [2'-(13)C]-OxyLH2, [3'-(15)N]-OxyLH2), five closely related structural analogues, and theoretically computed spectra. The computed DFT harmonic vibrational force fields (B3LYP and M06 functionals with basis sets of varying flexibility up to 6-311++G**) reproduce well the observed shifts in the IR spectra of both isotopically labeled and structurally related analogues.

  11. A guide for the laboratory information management system (LIMS) for light stable isotopes--Versions 7 and 8

    USGS Publications Warehouse

    Coplen, Tyler B.

    2000-01-01

    The reliability and accuracy of isotopic data can be improved by utilizing database software to (i) store information about samples, (ii) store the results of mass spectrometric isotope-ratio analyses of samples, (iii) calculate analytical results using standardized algorithms stored in a database, (iv) normalize stable isotopic data to international scales using isotopic reference materials, and (v) generate multi-sheet paper templates for convenient sample loading of automated mass-spectrometer sample preparation manifolds. Such a database program, the Laboratory Information Management System (LIMS) for Light Stable Isotopes, is presented herein. Major benefits of this system include (i) a dramatic improvement in quality assurance, (ii) an increase in laboratory efficiency, (iii) a reduction in workload due to the elimination or reduction of retyping of data by laboratory personnel, and (iv) a decrease in errors in data reported to sample submitters. Such a database provides a complete record of when and how often laboratory reference materials have been analyzed and provides a record of what correction factors have been used through time. It provides an audit trail for laboratories. LIMS for Light Stable Isotopes is available for both Microsoft Office 97 Professional and Microsoft Office 2000 Professional as versions 7 and 8, respectively. Both source code (mdb file) and precompiled executable files (mde) are available. Numerous improvements have been made for continuous flow isotopic analysis in this version (specifically 7.13 for Microsoft Access 97 and 8.13 for Microsoft Access 2000). It is much easier to import isotopic results from Finnigan ISODAT worksheets, even worksheets on which corrections for amount of sample (linearity corrections) have been added. The capability to determine blank corrections using isotope mass balance from analyses of elemental analyzer samples has been added. It is now possible to calculate and apply drift corrections to isotopic

  12. Synergy of metal and nonmetal dopants for visible-light photocatalysis: a case-study of Sn and N co-doped TiO2.

    PubMed

    Zhuang, Huaqiang; Zhang, Yingguang; Chu, Zhenwei; Long, Jinlin; An, Xiaohan; Zhang, Hongwen; Lin, Huaxiang; Zhang, Zizhong; Wang, Xuxu

    2016-04-14

    This paper mainly focuses on the synergistic effect of Sn and N dopants to enhance the photocatalytic performance of anatase TiO2 under visible light or simulated solar light irradiation. The Sn and N co-doped TiO2 (SNT-x) photocatalysts were successfully prepared by the facile sol-gel method and the post-nitridation route in the temperature range of 400-550 °C. All the as-prepared samples were characterized in detail by X-ray diffraction, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy, X-ray photoelectron and electron spin resonance spectroscopy and photoelectrochemical measurements. The characterization results reveal that the co-incorporation of Sn and N atoms remarkably modifies the electronic structure of TiO2, which gives rise to a prominent separation of photogenerated charge carriers and more efficient interfacial charge-transfer reactions in a photocatalytic process. The enhanced photocatalytic activity is attributed to the intensified active oxygen species including hydroxyl radicals (˙OH) and superoxide anion radicals (O2˙(-)) for degradation of organic pollutants. And the result of photocatalytic hydrogen production further confirms the existence of the synergistic effect in the SNT-x samples, because they exhibit higher photocatalytic activity than the sum of N/TiO2 and Sn/TiO2. This work provides a paradigm to consolidate the understanding of the synergistic effect of metal and non-metal co-doped TiO2 in domains of photocatalysis and photoelectrochemistry.

  13. Controlling factors of Ca isotope fractionation in scleractinian corals evaluated by temperature, pH and light controlled culture experiments

    NASA Astrophysics Data System (ADS)

    Inoue, Mayuri; Gussone, Nikolaus; Koga, Yasuko; Iwase, Akihiro; Suzuki, Atsushi; Sakai, Kazuhiko; Kawahata, Hodaka

    2015-10-01

    In this study, the 44Ca/40Ca ratios of Porites australiensis grown under three different culture experiments composed of temperature, pH and light controlled culture experiments are measured. The temperature dependent isotope fractionation of 0.02‰/°C deduced from this study is similar to inorganic aragonite, but the degree of isotope fractionation is about +0.4‰ offset in corals. These observations agree with earlier results on different coral species, suggesting Ca isotope fractionation during Ca transmembrane transport in corals. While in cultured corals a significant temperature dependence of δ44Ca is observed, the relationships between calcium isotope fractionation and pH as well as light intensity are negligible. Therefore variation of δ44Ca in Porites corals is mainly controlled by temperature. A combination of δ44Ca and Sr/Ca of corals in temperature controlled experiments cannot be explained by Rayleigh type fractionation directly from a fluid, which is seawater-like in terms of δ44Ca and Sr/Ca. Through coral-specific biomineralization processes, overall mean δ44Ca of scleractinian corals including previous studies are different from biogenic aragonites secreted by sclerosponges and pteropods, but are comparable with those of bivalves as well as calcitic coccolithophores and foraminifers. These findings are important for better understanding biomineralization in corals and in order to constrain the Ca isotopic composition of oceanic Ca sinks in response to climate changes and associated with shifts of calcite and aragonite seas.

  14. Control of Surface Plasmon Resonance of Au/SnO2 by Modification with Ag and Cu for Photoinduced Reactions under Visible-Light Irradiation over a Wide Range.

    PubMed

    Tanaka, Atsuhiro; Hashimoto, Keiji; Kominami, Hiroshi

    2016-03-18

    Gold particles supported on tin(IV) oxide (0.2 wt% Au/SnO2) were modified with copper and silver by the multistep photodeposition method. Absorption around λ=550 nm, attributed to surface plasmon resonance (SPR) of Au, gradually shifted to longer wavelengths on modification with Cu and finally reached λ=620 nm at 0.8 wt% Cu. On the other hand, the absorption shifted to shorter wavelength with increasing amount of Ag and reached λ=450 nm at 0.8 wt% Ag. These Cu- and Ag-modified 0.2 wt% Au/SnO2 materials (Cu-Au/SnO2 and Ag-Au/SnO2) and 1.0 wt% Au/SnO2 were used for mineralization of formic acid to carbon dioxide in aqueous suspension under irradiation with visible light from a xenon lamp and three kinds of light-emitting diodes with different wavelengths. The reaction rates for the mineralization of formic acid over these materials depend on the wavelength of light. Apparent quantum efficiencies of Cu-Au/SnO2, Au/SnO2, and Ag-Au/SnO2 reached 5.5% at 625 nm, 5.8% at 525 nm, and 5.1% at 450 nm, respectively. These photocatalysts can also be used for selective oxidation of alcohols to corresponding carbonyl compounds in aqueous solution under visible-light irradiation. Broad responses to visible light in formic acid mineralization and selective alcohol oxidation were achieved when the three materials were used simultaneously.

  15. The complete visual light curve of SN 1987A: Thirteen months of FES observations. [IUE Fine Error Sensor (FES)

    NASA Technical Reports Server (NTRS)

    Sonneborn, G.

    1988-01-01

    Visual brightness measurements of SN 1987A are being obtained with the IUE acquisition camera and star tracker Fine Error Sensor, (FES) as part of each ultraviolet observation. Due to IUE's around-the-clock operation and lack of clouds, the FES record of SN 1987A provides the most complete set of visual photometry of the supernova made by any single instrument. The data illustrate the photometric limitations of the FES (+ or - 0.03 mag). Use of differential photometric methods are recommended for IUE observers desiring accurate photometry from FES measurements made during their observing shifts.

  16. Correlation of stable oxygen isotope temperature record with light attenuation profiles in reef-dwelling Tridacna shells

    NASA Astrophysics Data System (ADS)

    Pätzold, J.; Heinrichs, J. P.; Wolschendorf, K.; Wefer, G.

    1991-06-01

    Molluscs are known to record environmental changes in their carbonate shells in detail. This paper reports the findings of a high-resolution analysis of stable oxygen isotopic compositions and light transmission properties of a shell of the reef-dwelling Pacific giant clam Tridacna gigas. Our findings reveal that the annual growth rates and the longevity of Tridacna specimens can be readily determined by measuring the annual light attenuation pattern within the shell. Annual seasonal changes in water temperature are reflected with high resolution in the stable oxygen isotope ratios and in the light attenuation values of the aragonite shell. The inner shell of T. gigas deposited below the pallial line revealing undisturbed shell accretion with high growth rates shows the maximum seasonal oxygen isotope range and the highest resolution in light attenuation changes. We suggest that this is the best part of the shell to reconstruct former seasonal surface water temperatures in tropical environments. Scanning electron microscopy (SEM) studies suggest that the annual growth patterns observed in transmitted light are generated by a complex pattern of daily growth increments with varying sizes of skeletal crystallites and varying amounts of organic carbon.

  17. Tissue S/N ratios and stable isotopes (delta(34)S and delta(15)N) of epilithic mosses (Haplocladium microphyllum) for showing air pollution in urban cities in Southern China.

    PubMed

    Xiao, Hua-Yun; Tang, Cong-Guo; Xiao, Hong-Wei; Wang, Yan-Li; Liu, Xue-Yan; Liu, Cong-Qiang

    2010-05-01

    In urban cities in Southern China, the tissue S/N ratios of epilithic mosses (Haplocladium microphyllum), varied widely from 0.11 to 0.19, are strongly related to some atmospheric chemical parameters (e.g. rainwater SO(4)(2-)/NH(4)(+) ratios, each people SO(2) emission). If tissue S/N ratios in the healthy moss species tend to maintain a constant ratio of 0.15 in unpolluted area, our study cities can be divided into two classes: class I (S/N > 0.15, S excess) and class II (S/N < 0.15, N excess), possibly indicative of stronger industrial activity and higher density of population, respectively. Mosses in all these cities obtained S and N from rainwater at a similar ratio. Sulphur and N isotope ratios in mosses are found significantly linearly correlated with local coal delta(34)S and NH(4)(+)-N wet deposition, respectively, indicating that local coal and animal NH(3) are the major atmospheric S and N sources.

  18. Forensic applications of light-element stable isotope ratios of Ricinus communis seeds and ricin preparations.

    PubMed

    Kreuzer, Helen W; West, Jason B; Ehleringer, James R

    2013-01-01

    Seeds of the castor plant Ricinus communis are of forensic interest because they are the source of the poison ricin. We tested whether stable isotope ratios of castor seeds and ricin preparations can be used as a forensic signature. We collected over 300 castor seed samples worldwide and measured the C, N, O, and H isotope ratios of the whole seeds and oil. We prepared ricin by three different procedures, acetone extraction, salt precipitation, and affinity chromatography, and compared their isotope ratios to those of the source seeds. The N isotope ratios of the ricin samples and source seeds were virtually identical. Therefore, N isotope ratios can be used to correlate ricin prepared by any of these methods to source seeds. Further, stable isotope ratios distinguished >99% of crude and purified ricin protein samples in pairwise comparison tests. Stable isotope ratios therefore constitute a valuable forensic signature for ricin preparations.

  19. Light element isotopic compositions of cometary matter returned by the STARDUST mission

    SciTech Connect

    McKeegan, K D; Aleon, J; Bradley, J; Brownlee, D; Busemann, H; Butterworth, A; Chaussidon, M; Fallon, S; Floss, C; Gilmour, J; Gounelle, M; Graham, G; Guan, Y; Heck, P R; Hoppe, P; Hutcheon, I D; Huth, J; Ishii, H; Ito, M; Jacobsen, S B; Kearsley, A; Leshin, L A; Liu, M; Lyon, I; Marhas, K; Marty, B; Matrajt, G; Meibom, A; Messenger, S; Mostefaoui, S; Nakamura-Messenger, K; Nittler, L; Palma, R; Pepin, R O; Papanastassiou, D A; Robert, F; Schlutter, D; Snead, C J; Stadermann, F J; Stroud, R; Tsou, P; Westphal, A; Young, E D; Ziegler, K; Zimmermann, L; Zinner, E

    2006-10-10

    Hydrogen, carbon, nitrogen, and oxygen isotopic compositions are heterogeneous among comet 81P/Wild2 particle fragments, however extreme isotopic anomalies are rare, indicating that the comet is not a pristine aggregate of presolar materials. Non-terrestrial nitrogen and neon isotope ratios suggest that indigenous organic matter and highly volatile materials were successfully collected. Except for a single circumstellar stardust grain, silicate and oxide minerals have oxygen isotopic compositions consistent with solar system origin. One refractory grain is {sup 16}O-enriched like refractory inclusions in meteorites, suggesting formation in the hot inner solar nebula and large-scale radial transport prior to comet accretion in the outer solar system.

  20. Tuning the surface charge of graphene for self-assembly synthesis of a SnNb2O6 nanosheet-graphene (2D-2D) nanocomposite with enhanced visible light photoactivity

    NASA Astrophysics Data System (ADS)

    Yuan, Lan; Yang, Min-Quan; Xu, Yi-Jun

    2014-05-01

    A two-dimensional (2D) SnNb2O6 nanosheet-graphene (SnNb2O6-GR) nanocomposite featuring a typical 2D-2D structure has been synthesized via a simple surface charge modified self-assembly approach. The method is afforded by electrostatic attractive interaction between negatively charged SnNb2O6 nanosheets and modified graphene nanosheets with a positively charged surface in an aqueous solution. The SnNb2O6-GR nanocomposite exhibits a distinctly enhanced visible light photocatalytic performance toward degradation of organic dye in water as compared to blank SnNb2O6 nanosheets. The enhanced photoactivity is attributed to the integrated factors of the intimate interfacial contact and unique 2D-2D morphology associated with SnNbO6 and GR, which are beneficial for harnessing the electron conductivity of GR, facilitating the transfer and separation of photogenerated charge carriers over SnNbO6-GR upon visible light irradiation, and thereby contributing to the photoactivity enhancement. It is hoped that this work could enrich the facile, efficient fabrication of various 2D-2D semiconductor nanosheet-graphene composite photocatalysts toward target photocatalytic applications.A two-dimensional (2D) SnNb2O6 nanosheet-graphene (SnNb2O6-GR) nanocomposite featuring a typical 2D-2D structure has been synthesized via a simple surface charge modified self-assembly approach. The method is afforded by electrostatic attractive interaction between negatively charged SnNb2O6 nanosheets and modified graphene nanosheets with a positively charged surface in an aqueous solution. The SnNb2O6-GR nanocomposite exhibits a distinctly enhanced visible light photocatalytic performance toward degradation of organic dye in water as compared to blank SnNb2O6 nanosheets. The enhanced photoactivity is attributed to the integrated factors of the intimate interfacial contact and unique 2D-2D morphology associated with SnNbO6 and GR, which are beneficial for harnessing the electron conductivity of GR

  1. Microbial production of isotopically light iron(II) in a modern chemically precipitated sediment and implications for isotopic variations in ancient rocks

    USGS Publications Warehouse

    Tangalos, G.E.; Beard, B.L.; Johnson, C.M.; Alpers, C.N.; Shelobolina, E.S.; Xu, H.; Konishi, H.; Roden, E.E.

    2012-01-01

    The inventories and Fe isotope composition of aqueous Fe(II) and solid-phase Fe compounds were quantified in neutral-pH, chemically precipitated sediments downstream of the Iron Mountain acid mine drainage site in northern California, USA. The sediments contain high concentrations of amorphous Fe(III) oxyhydroxides [Fe(III)am] that allow dissimilatory iron reduction (DIR) to predominate over Fe–S interactions in Fe redox transformation, as indicated by the very low abundance of Cr(II)-extractable reduced inorganic sulfur compared with dilute HCl-extractable Fe. δ56Fe values for bulk HCl- and HF-extractable Fe were ≈ 0. These near-zero bulk δ56Fe values, together with the very low abundance of dissolved Fe in the overlying water column, suggest that the pyrite Fe source had near-zero δ56Fe values, and that complete oxidation of Fe(II) took place prior to deposition of the Fe(III) oxide-rich sediment. Sediment core analyses and incubation experiments demonstrated the production of millimolar quantities of isotopically light (δ56Fe ≈ -1.5 to -0.5‰) aqueous Fe(II) coupled to partial reduction of Fe(III)am by DIR. Trends in the Fe isotope composition of solid-associated Fe(II) and residual Fe(III)am are consistent with experiments with synthetic Fe(III) oxides, and collectively suggest an equilibrium Fe isotope fractionation between aqueous Fe(II) and Fe(III)am of approximately -2‰. These Fe(III) oxide-rich sediments provide a model for early diagenetic processes that are likely to have taken place in Archean and Paleoproterozoic marine sediments that served as precursors for banded iron formations. Our results suggest pathways whereby DIR could have led to the formation of large quantities of low-δ56Fe minerals during BIF genesis.

  2. Forensic Applications of Light-Element Stable Isotope Ratios of Ricinus communis Seeds and Ricin Preparations

    SciTech Connect

    Kreuzer, Helen W.; West, Jason B.; Ehleringer, James

    2013-01-01

    Seeds of the castor plant Ricinus communis, also known as castor beans, are of forensic interest because they are the source of the poison ricin. We have tested whether stable isotope ratios of castor seeds and ricin prepared by various methods can be used as a forensic signature. We collected over 300 castor seed samples from locations around the world and measured the C, N, O, and H stable isotope ratios of the whole seeds, oil, and three types of ricin preparations. Our results demonstrate that N isotope ratios can be used to correlate ricin prepared by any of these methods to source seeds. Further, stable isotope ratios distinguished >99% of crude and purified ricin protein samples in pair-wise comparison tests. Stable isotope ratios therefore constitute a valuable forensic signature for ricin preparations.

  3. High Light Absorption and Charge Separation Efficiency at Low Applied Voltage from Sb-Doped SnO2/BiVO4 Core/Shell Nanorod-Array Photoanodes.

    PubMed

    Zhou, Lite; Zhao, Chenqi; Giri, Binod; Allen, Patrick; Xu, Xiaowei; Joshi, Hrushikesh; Fan, Yangyang; Titova, Lyubov V; Rao, Pratap M

    2016-06-01

    BiVO4 has become the top-performing semiconductor among photoanodes for photoelectrochemical water oxidation. However, BiVO4 photoanodes are still limited to a fraction of the theoretically possible photocurrent at low applied voltages because of modest charge transport properties and a trade-off between light absorption and charge separation efficiencies. Here, we investigate photoanodes composed of thin layers of BiVO4 coated onto Sb-doped SnO2 (Sb:SnO2) nanorod-arrays (Sb:SnO2/BiVO4 NRAs) and demonstrate a high value for the product of light absorption and charge separation efficiencies (ηabs × ηsep) of ∼51% at an applied voltage of 0.6 V versus the reversible hydrogen electrode, as determined by integration of the quantum efficiency over the standard AM 1.5G spectrum. To the best of our knowledge, this is one of the highest ηabs × ηsep efficiencies achieved to date at this voltage for nanowire-core/BiVO4-shell photoanodes. Moreover, although WO3 has recently been extensively studied as a core nanowire material for core/shell BiVO4 photoanodes, the Sb:SnO2/BiVO4 NRAs generate larger photocurrents, especially at low applied voltages. In addition, we present control experiments on planar Sb:SnO2/BiVO4 and WO3/BiVO4 heterojunctions, which indicate that Sb:SnO2 is more favorable as a core material. These results indicate that integration of Sb:SnO2 nanorod cores with other successful strategies such as doping and coating with oxygen evolution catalysts can move the performance of BiVO4 and related semiconductors closer to their theoretical potential.

  4. Improvement of water and light availability after thinning at a xeric site: which matters more? A dual isotope approach.

    PubMed

    Giuggiola, Arnaud; Ogée, Jérôme; Rigling, Andreas; Gessler, Arthur; Bugmann, Harald; Treydte, Kerstin

    2016-04-01

    Thinning fosters individual tree growth by increasing the availability of water, light and nutrients. At sites where water rather than light is limiting, thinning also enhances soil evaporation and might not be beneficial. Detailed knowledge of the short- to long-term physiological response underlying the growth responses to thinning is crucial for the management of forests already suffering from recurrent drought-induced dieback. We applied a dual isotope approach together with mechanistic isotope models to study the physiological processes underlying long-term growth enhancement of heavily thinned Pinus sylvestris in a xeric forest in Switzerland. This approach allowed us to identify and disentangle thinning-induced changes in stomatal conductance and assimilation rate. At our xeric study site, the increase in stomatal conductance far outweighed the increase in assimilation, implying that growth release in heavily thinned trees is primarily driven by enhanced water availability rather than increased light availability. We conclude that in forests with relatively isohydric species (drought avoiders) that are growing close to their physiological limits, thinning is recommended to maintain a less negative water balance and thus foster tree growth, and ultimately the survival of forest trees under drought.

  5. Improvement of water and light availability after thinning at a xeric site: which matters more? A dual isotope approach.

    PubMed

    Giuggiola, Arnaud; Ogée, Jérôme; Rigling, Andreas; Gessler, Arthur; Bugmann, Harald; Treydte, Kerstin

    2016-04-01

    Thinning fosters individual tree growth by increasing the availability of water, light and nutrients. At sites where water rather than light is limiting, thinning also enhances soil evaporation and might not be beneficial. Detailed knowledge of the short- to long-term physiological response underlying the growth responses to thinning is crucial for the management of forests already suffering from recurrent drought-induced dieback. We applied a dual isotope approach together with mechanistic isotope models to study the physiological processes underlying long-term growth enhancement of heavily thinned Pinus sylvestris in a xeric forest in Switzerland. This approach allowed us to identify and disentangle thinning-induced changes in stomatal conductance and assimilation rate. At our xeric study site, the increase in stomatal conductance far outweighed the increase in assimilation, implying that growth release in heavily thinned trees is primarily driven by enhanced water availability rather than increased light availability. We conclude that in forests with relatively isohydric species (drought avoiders) that are growing close to their physiological limits, thinning is recommended to maintain a less negative water balance and thus foster tree growth, and ultimately the survival of forest trees under drought. PMID:26639082

  6. Light stable isotope study of the Roosevelt Hot Springs thermal area, Southwestern Utah

    SciTech Connect

    Rohrs D.T.; Bowman, J.R.

    1980-05-01

    The isotopic composition of hydrogen, oxygen, and carbon has been determined for regional cold springs, thermal fluids, and rocks and minerals from the Roosevelt Hot Springs thermal area. The geothermal system has developed within plutonic granitic rocks and amphibolite facies gneiss, relying upon fracture-controlled permeability for the migration of the thermal fluids. Probably originating as meteoric waters in the upper elevations of the Mineral Mountains, the thermal waters sampled in the production wells display an oxygen isotopic shift of at least +1.2. Depletions of delta /sup 18/O in wole rock, K-feldspar, and biotite have a positive correlation with alteration intensity. W/R mass ratios, calculated from the isotopic shifts of rock and water, range up to 3.0 in a producing horizon of one well, although the K-feldspar has experienced only 30% exchange with the thermal waters. While veinlet quartz has equilibrated with the thermal waters, the /sup 18/O values of K-mica clay, an alteration product of plagioclase, mimic the isotopic composition of K-feldspar and whole rock. This suggests that locally small W/R ratios enable plagioclase to influence its alteration products by isotopic exchange.

  7. Lithium isotopes and light lithophile element abundances in shergottites: Evidence for both magmatic degassing and subsolidus diffusion

    NASA Astrophysics Data System (ADS)

    Udry, Arya; McSween, Harry Y.; Hervig, Richard L.; Taylor, Lawrence A.

    2016-01-01

    Degassed magmatic water was potentially the major source of surficial water on Mars. We measured Li, B, and Be abundances and Li isotope profiles in pyroxenes, olivines, and maskelynite from four compositionally different shergottites—Shergotty, QUE 94201, LAR 06319, and Tissint—using secondary ion mass spectrometry (SIMS). All three light lithophile elements (LLE) are incompatible: Li and B are soluble in H2O-rich fluids, whereas Be is insoluble. In the analyzed shergottites, Li concentration decreases and Be concentration increases from cores to rims in pyroxenes. However, B concentrations do not vary consistently with Li and Be abundances, except in QUE 94201 pyroxenes. Additionally, abundances of these three elements in olivines show a normal igneous-fractionation trend consistent with the crystallization of olivine before magma ascent and degassing. We expect that kinetic effects would lead to fractionation of 6Li in the vapor phase compared to 7Li during degassing. The Li isotope profiles, with increasing δ7Li from cores to rims, as well as Li and B profiles indicate possible degassing of hydrous fluids only for the depleted shergottite QUE 94201, as also supported by degassing models. Conversely, Shergotty, LAR 06319, and Tissint appear to have been affected by postcrystallization diffusion, based on their LLE and Li isotope profiles, accompanied by diffusion models. This process may represent an overlay on a degassing pattern. The LLE profiles and isotope profiles in QUE 94201 support the hypothesis that degassing of some basaltic shergottite magmas provided water to the Martian surface, although evidence may be obscured by subsolidus diffusion processes.

  8. Coulomb excitation of 107Sn

    NASA Astrophysics Data System (ADS)

    DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekström, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhäuser, R.; Görgen, A.; Hess, H.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

    2012-07-01

    The radioactive isotope 107Sn was studied using Coulomb excitation at the REX-ISOLDE facility at CERN. This is the lightest odd-Sn nucleus examined using this technique. The reduced transition probability of the lowest-lying 3/2+ state was measured and is compared to shell-model predictions based on several sets of single-neutron energies relative to 100Sn . Similar to the transition probabilities for the 2+ states in the neutron-deficient even-even Sn nuclei, the measured value is underestimated by shell-model calculations. Part of the strength may be recovered by considering the ordering of the d_{5/2} and g_{7/2} single-neutron states.

  9. Water and light improvement after thinning at a xeric site: Which weights the most? A dual isotope approach

    NASA Astrophysics Data System (ADS)

    Giuggiola, Arnaud; Ogée, Jérôme; Gessler, Arthur; Rigling, Andreas; Bugmann, Harald; Treydte, Kerstin

    2015-04-01

    Reductions in stand density foster individual tree growth due to increases of resources such as water, light and nutrients. Detailed knowledge of the short- to long-term physiological response underlying the growth response to thinning is crucial for the management of forests already suffering from recurrent drought-induced dieback. We applied a dual isotope approach together with mechanistic isotope models such as MuSICA to study the physiological processes underlying growth enhancement in a long-term thinning experiment in a xeric Pinus sylvestris forest in Switzerland. This approach allowed for identifying and disentangling changes in stomatal conductance and assimilation rate. Our results indicate that an increase in stomatal conductance outweighs an increase in assimilation, meaning that the observed growth releases in heavy thinned trees at our xeric site are primarily driven by enhanced water availability rather than by the increase in light availability. We conclude that in areas with isohydric species (drought avoiders) that tend to grow close to their physiological limits, thinning is highly recommended to maintain a less negative water balance and thus foster tree growth, and ultimately the survival rate of individual trees and forests.

  10. Magnetic Moments of States in 110Sn.

    NASA Astrophysics Data System (ADS)

    Kumbartzki, G. J.

    2016-06-01

    The semi-magic Sn isotopes with Z = 50 are the subject of extensive experimental and theoretical studies. The measured B(E2) values to the 21 + states for the neutron-deficient side of the isotope chain suggest enhanced collectivity when fewer particles are available if the proton shell is not broken. Magnetic moments which are sensitive to proton and neutron contributions to the wave functions of the states could provide critical and relevant information. Magnetic moments were previously measured only for the even stable and a few neutron-rich unstable Sn isotopes. A measurement of the g factors of excited states in 110Sn using the transient field technique was performed at the 88-Inch Cyclotron at the LBNL in Berkeley. The 110Sn nuclei were produced via an α-particle transfer to 106Cd.

  11. ISOTOPIC COMPOSITION OF LIGHT NUCLEI IN COSMIC RAYS: RESULTS FROM AMS-01

    SciTech Connect

    Aguilar, M.; Alcaraz, J.; Berdugo, J.; Allaby, J.; Alpat, B.; Ambrosi, G.; Azzarello, P.; Battiston, R.; Anderhub, H.; Ao, L.; Arefiev, A.; Arruda, L.; Barao, F.; Barreira, G.; Basile, M.; Bellagamba, L.; Bartoloni, A.; Becker, R.; Becker, U.; Berges, P.

    2011-08-01

    The variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the heliosphere. In this paper, we present measurements of the isotopic ratios {sup 2}H/{sup 4}He, {sup 3}He/{sup 4}He, {sup 6}Li/{sup 7}Li, {sup 7}Be/({sup 9}Be+{sup 10}Be), and {sup 10}B/{sup 11}B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June.

  12. COMPARISON OF SELF-CONSISTENT SKYRME AND GOGNY CALCULATIONS FOR LIGHT Hg ISOTOPES

    SciTech Connect

    Warda, Michal J; Prochniak, L.; Staszczak, Andrzej

    2010-01-01

    The ground-state properties of neutron-deficient Hg isotopes have been investigated by the constrained self-consistent Hartree-Fock-Bogoliubov approach with the Skyrme and Gogny effective forces. In the case of the Skyrme interaction we have also applied the Hartree-Fock+BCS model with the state-dependent {delta}-pairing interaction. Potential energy surfaces and pairing properties have been compared for the both types of forces.

  13. Determination of Light Water Reactor Fuel Burnup with the Isotope Ratio Method

    SciTech Connect

    Gerlach, David C.; Mitchell, Mark R.; Reid, Bruce D.; Gesh, Christopher J.; Hurley, David E.

    2007-11-01

    For the current project to demonstrate that isotope ratio measurements can be extended to zirconium alloys used in LWR fuel assemblies we report new analyses on irradiated samples obtained from a reactor. Zirconium alloys are used for structural elements of fuel assemblies and for the fuel element cladding. This report covers new measurements done on irradiated and unirradiated zirconium alloys, Unirradiated zircaloy samples serve as reference samples and indicate starting values or natural values for the Ti isotope ratio measured. New measurements of irradiated samples include results for 3 samples provided by AREVA. New results indicate: 1. Titanium isotope ratios were measured again in unirradiated samples to obtain reference or starting values at the same time irradiated samples were analyzed. In particular, 49Ti/48Ti ratios were indistinguishably close to values determined several months earlier and to expected natural values. 2. 49Ti/48Ti ratios were measured in 3 irradiated samples thus far, and demonstrate marked departures from natural or initial ratios, well beyond analytical uncertainty, and the ratios vary with reported fluence values. The irradiated samples appear to have significant surface contamination or radiation damage which required more time for SIMS analyses. 3. Other activated impurity elements still limit the sample size for SIMS analysis of irradiated samples. The sub-samples chosen for SIMS analysis, although smaller than optimal, were still analyzed successfully without violating the conditions of the applicable Radiological Work Permit

  14. Discrimination between ginseng from Korea and China by light stable isotope analysis.

    PubMed

    Horacek, Micha; Min, Ji-Sook; Heo, Sang-Cheol; Soja, Gerhard

    2010-12-01

    Ginseng is a health food and traditional medicine highly valued in Asia. Ginseng from certain origins is higher valued than from other origins, so that a reliable method for differentiation of geographical origin is important for the economics of ginseng production. To discriminate between ginseng samples from South Korea and PR China, 29 samples have been analyzed for the isotopic composition of the elements H, C and N. The results showed δ(2)H values between -94 and -79‰, for δ(13)C -27.9 to -23.7‰ and for δ(15)N 1.3-5.4‰ for Chinese ginseng. Korean ginseng gave δ(2)H ratios between -91 and -69‰, δ(13)C ratios between -31.2 and -22.4‰ and δ(15)N ratios between -2.4 and +7‰. Despite the overlap between the values for individual isotopes, a combination of the isotope systems gave a reasonable differentiation between the two geographic origins. Especially the statistically significant difference in δ(2)H ratios facilitated the differentiation between Korean and Chinese ginseng samples.

  15. Isotopically nonstationary 13C flux analysis of changes in Arabidopsis thaliana leaf metabolism due to high light acclimation.

    PubMed

    Ma, Fangfang; Jazmin, Lara J; Young, Jamey D; Allen, Doug K

    2014-11-25

    Improving plant productivity is an important aim for metabolic engineering. There are few comprehensive methods that quantitatively describe leaf metabolism, although such information would be valuable for increasing photosynthetic capacity, enhancing biomass production, and rerouting carbon flux toward desirable end products. Isotopically nonstationary metabolic flux analysis (INST-MFA) has been previously applied to map carbon fluxes in photoautotrophic bacteria, which involves model-based regression of transient (13)C-labeling patterns of intracellular metabolites. However, experimental and computational difficulties have hindered its application to terrestrial plant systems. We performed in vivo isotopic labeling of Arabidopsis thaliana rosettes with (13)CO2 and estimated fluxes throughout leaf photosynthetic metabolism by INST-MFA. Plants grown at 200 µmol m(-2)s(-1) light were compared with plants acclimated for 9 d at an irradiance of 500 µmol⋅m(-2)⋅s(-1). Approximately 1,400 independent mass isotopomer measurements obtained from analysis of 37 metabolite fragment ions were regressed to estimate 136 total fluxes (54 free fluxes) under each condition. The results provide a comprehensive description of changes in carbon partitioning and overall photosynthetic flux after long-term developmental acclimation of leaves to high light. Despite a doubling in the carboxylation rate, the photorespiratory flux increased from 17 to 28% of net CO2 assimilation with high-light acclimation (Vc/Vo: 3.5:1 vs. 2.3:1, respectively). This study highlights the potential of (13)C INST-MFA to describe emergent flux phenotypes that respond to environmental conditions or plant physiology and cannot be obtained by other complementary approaches. PMID:25368168

  16. Isospin transport in 84Kr+112,124Sn collisions at Fermi energies

    NASA Astrophysics Data System (ADS)

    Barlini, S.; Piantelli, S.; Casini, G.; Maurenzig, P. R.; Olmi, A.; Bini, M.; Carboni, S.; Pasquali, G.; Poggi, G.; Stefanini, A. A.; Bougault, R.; Bonnet, E.; Borderie, B.; Chbihi, A.; Frankland, J. D.; Gruyer, D.; Lopez, O.; Le Neindre, N.; Pârlog, M.; Rivet, M. F.; Vient, E.; Rosato, E.; Spadaccini, G.; Vigilante, M.; Bruno, M.; Marchi, T.; Morelli, L.; Cinausero, M.; Degerlier, M.; Gramegna, F.; Kozik, T.; Twaróg, T.; Alba, R.; Maiolino, C.; Santonocito, D.

    2013-05-01

    Isotopically resolved fragments with Z≲20 have been studied with a high-resolution telescope in a test run for the FAZIA Collaboration. The fragments were produced by the collision of a 84Kr beam at 35 MeV/nucleon with a neutron-rich (124Sn) and a neutron-poor (112Sn) target. The fragments, detected close to the grazing angle, are mainly emitted from the phase-space region of the projectile. The fragment isotopic content clearly depends on the neutron richness of the target and this is direct evidence of isospin diffusion between projectile and target. The observed enhanced neutron richness of light fragments emitted from the phase-space region close to the center of mass of the system can be interpreted as an effect of isospin drift in the diluted neck region.

  17. Photocatalytic performance of Sn-doped TiO{sub 2} nanostructured thin films for photocatalytic degradation of malachite green dye under UV and VIS-lights

    SciTech Connect

    Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Sener, S.; Arpac, E.; Sayilkan, H.

    2008-01-08

    Sn-doped and undoped nano-TiO{sub 2} particles have been synthesized by hydrotermal process without acid catalyst at 225 deg. C in 1 h. Nanostructure-TiO{sub 2} based thin films, contain at different solid ratio of TiO{sub 2} in coating, have been prepared on glass surfaces by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, BET and UV/VIS/NIR techniques. The photocatalytic performance of the films was tested for degradation of malachite green dye in solution under UV and VIS-lights. The results showed that the hydrothermally synthesized nano-TiO{sub 2} particles are fully anatase crystalline form and are easily dispersed in water, the coated surfaces have nearly super-hydrophilic properties and, the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO{sub 2} thin film. The results also proved that malachite green is decomposed catalytically due to the pseudo first-order reaction kinetics.

  18. An investigation of trace and isotope light elements in mineral phases from well RN-17 (Reykjanes Peninsula, SW Iceland)

    NASA Astrophysics Data System (ADS)

    Raffone, N.; Ottolini, L. P.; Tonarini, S.; Gianelli, G.; D'Orazio, M.; Fridleifsson, G. Ó.

    2010-02-01

    The light lithophile (Li, Be and B) and halogen (F, Cl) elements are powerful tracers of fluid transfer due to their mobility during high temperature hydrothermal processes and metamorphic devolatilisation. Moreover, although a great deal of studies have been carried out on these elements in whole rock and minerals of altered rocks from divergent and convergent plate margins, an inventory for mineral phases from the altered Icelandic oceanic crust is still incomplete. In the present paper we report the results of in situ EPMA and SIMS investigations on variously altered magmatic (plagioclase and clinopyroxene) and hydrothermal phases (amphibole and epidote) from selected cuttings drilled at different depths (400 - 3000 m) of the well RN-17, Reykjanes geothermal system (SW Iceland). Our study has benefited from the use of high-magnification SEM investigations; from ICP-MS on Li, P-TIMS determinations of boron isotope composition (δ11B) and ID analyses of B contents on the whole rock. Particularly, SIMS data on epidote have shown that alteration beneath Reykjanes has been more efficient in the shallow and intermediate cuttings, while whole rock data on boron isotope composition have revealed that the alteration has been caused firstly by δ11B-poor fluids and successively by δ11B-rich seawater-hydrothermal fluids.

  19. Production of isotopically heavy ozone by ultraviolet light photolysis of O2

    NASA Technical Reports Server (NTRS)

    Thiemens, Mark H.; Jackson, Teresa

    1987-01-01

    Ozone was produced by UV photolysis (157-200 nm) of molecular oxygen. The product ozone is enriched in O-17 and O-18 on a mass-independent basis, similar to the fractionations observed in an electrical discharge. The magnitude of O-18 and O-17 enrichment decreases with decreasing pressure, suggesting the presence of two fractionation mechanisms with differing delta-O-17/delta-O-18 ratios. One of the end members would be mass-independent with delta-O-18 equal to delta-O-17 equal to about 90 percent, which is dominant above about 20 torr. The second process which is significant below about 6 torr produces O3 with delta-O-18 equals about -55 percent, delta-O-17 equals about -27.5, possibly due to isotopic selectivity in diffusion to the reaction systems wall. The delta-O-17 = delta-O-18 isotopic fractionation resembles that observed in stratospheric ozone, though the magnitude of fractionation is a factor of four less.

  20. METHOD FOR REMOVAL OF LIGHT ISOTOPE PRODUCT FROM LIQUID THERMAL DIFFUSION UNITS

    DOEpatents

    Hoffman, J.D.; Ballou, J.K.

    1957-11-19

    A method and apparatus are described for removing the lighter isotope of a gaseous-liquid product from a number of diffusion columns of a liquid thermal diffusion system in two stages by the use of freeze valves. The subject liquid flows from the diffusion columns into a heated sloping capsule where the liquid is vaporized by the action of steam in a heated jacket surrounding the capsule. When the capsule is filled the gas flows into a collector. Flow between the various stages is controlled by freeze valves which are opened and closed by the passage of gas and cool water respectively through coils surrounding portions of the pipes through which the process liquid is passed. The use of the dual stage remover-collector and the freeze valves is an improvement on the thermal diffusion separation process whereby the fraction containing the lighter isotope many be removed from the tops of the diffusion columns without intercolumn flow, or prior stage flow while the contents of the capsule is removed to the final receiver.

  1. The synthesis of the light Mo and Ru isotopes: how now, no need for an exotic solution?

    NASA Astrophysics Data System (ADS)

    Costa, V.; Rayet, M.; Zappalà, R. A.; Arnould, M.

    2000-06-01

    The most detailed calculations of the p-process call for its development in the O/Ne layers of Type II supernovae. In spite of their overall success in reproducing the solar system content of p-nuclides, they suggest a significant underproduction of the light Mo and Ru isotopes. On grounds of a model for the explosion of a 25 Msun star with solar metallicity, we demonstrate that this failure might just be related to the uncertainties left in the rate of the \\reac{22}{Ne}{\\alpha}{n}{25}{Mg} neutron producing reaction. The latter indeed have a direct impact on the distribution of the s-process seeds for the p-process.

  2. Fe-isotope fractionation in magmatic-hydrothermal mineral deposits: A case study from the Renison Sn-W deposit, Tasmania

    NASA Astrophysics Data System (ADS)

    Wawryk, Christine M.; Foden, John D.

    2015-02-01

    We present 50 new iron isotopic analyses of source granite and mineral separates from the Renison tin deposit in western Tasmania. The aim of the study is to characterise the composition of minerals within a tin deposit associated with a reduced, S-type magma. We have analysed bulk samples of granite, and separates of pyrrhotite, pyrite, arsenopyrite, magnetite, chalcopyrite and siderite by multi-collector inductively coupled mass spectrometry. The isotopic compositions of mineral separates are consistent with theoretical predictions of equilibrium fractionation based on Mössbauer spectroscopy and other parametric calculations. Mineral-mineral pairs yield temperatures of formation that are in agreement with prior detailed fluid inclusion studies, but are spatially inconsistent with declining fluid temperatures with distance from the causative intrusion, limiting the use of Fe isotopes as a potential geothermometer, at least in this case. Comparison of our data with published data from other deposits clearly demonstrates that pyrite, magnetite and chalcopyrite from the hottest ore fluids (>300-400 °C) at Renison are isotopically heavier than minerals sampled from a deposit formed at similar temperatures, but associated with a more oxidised and less differentiated intrusion.

  3. Optical investigations of InGaN heterostructures and GeSn nanocrystals for photonic and phononic applications: light emitting diodes and phonon cavities

    NASA Astrophysics Data System (ADS)

    Hafiz, Shopan din Ahmad

    InGaN heterostructures are at the core of blue light emitting diodes (LEDs) which are the basic building blocks for energy efficient and environment friendly modern white light generating sources. Through quantum confinement and electronic band structure tuning on the opposite end of the spectrum, Ge1-xSnx alloys have recently attracted significant interest due to its potential role as a silicon compatible infra-red (IR) optical material for photodetectors and LEDs owing to transition to direct bandgap with increasing Sn. This thesis is dedicated to establishing an understanding of the optical processes and carrier dynamics in InGaN heterostructures for achieving more efficient visible light emitters and terahertz generating nanocavities and in colloidal Ge1-xSnx quantum dots (QDs) for developing efficient silicon compatible optoelectronics. To alleviate the electron overflow, which through strong experimental evidence is revealed to be the dominating mechanism responsible for efficiency degradation at high injection in InGaN based blue LEDs, different strategies involving electron injectors and optimized active regions have been developed. Effectiveness of optimum electron injector (EI) layers in reducing electron overflow and increasing quantum efficiency of InGaN based LEDs was demonstrated by photoluminescence (PL) and electroluminescence spectroscopy along with numerical simulations. Increasing the two-layer EI thickness in double heterostructure LEDs substantially reduced the electron overflow and increased external quantum efficiency (EQE) by three fold. By incorporating delta p-doped InGaN barriers in multiple quantum well (MQW) LEDs, 20% enhancement in EQE was achieved due to improved hole injection without degrading the layer quality. Carrier diffusion length, an important physical parameter that directly affects the performance of optoelectronic devices, was measured in epitaxial GaN using PL spectroscopy. The obtained diffusion lengths at room

  4. From soil to grape and wine: Variation of light and heavy elements isotope ratios.

    PubMed

    Durante, Caterina; Bertacchini, Lucia; Bontempo, Luana; Camin, Federica; Manzini, Daniela; Lambertini, Paolo; Marchetti, Andrea; Paolini, Mauro

    2016-11-01

    In the development of a geographical traceability model, it is necessary to understand if the value of the monitored indicators in a food is correlated to its origin or if it is also influenced by 'external factors' such as those coming from its production. In this study, a deeper investigation of the trend of direct geographical traceability indicators along the winemaking process of two traditional oenological products was carried out. Different processes were monitored, sampling each step of their production (grape juice, intermediate products and wine). The results related to the determinations of δ(18)O, (D/H)I, (D/H)II, δ(13)C, δ(15)N and (87)Sr/(86)Sr have been reported. Furthermore, correspondence with the isotopic values coming from the respective soil and vine-branch samples have been investigated as well, showing the optimal traceability power of the monitored geographical tracers. PMID:27211693

  5. Excitation function of the alpha particle induced nuclear reactions on enriched 116Cd, production of the theranostic isotope 117mSn

    NASA Astrophysics Data System (ADS)

    Ditrói, F.; Takács, S.; Haba, H.; Komori, Y.; Aikawa, M.; Szűcs, Z.; Saito, M.

    2016-10-01

    117mSn is one of the radioisotopes can be beneficially produced through alpha particle irradiation. The targets were prepared by deposition of 116Cd metal onto high purity 12 μm thick Cu backing. The average deposited thickness was 21.9 μm. The beam energy was thoroughly measured by Time of Flight (TOF) methods and proved to be 51.2 MeV. For the experiment the well-established stacked foil technique was used. In addition to the Cd targets, Ti foils were also inserted into the stacks for energy and intensity monitoring. The Cu backings were also used for monitoring and as recoil catcher of the reaction products from the cadmium layer. The activities of the irradiated foils were measured with HPGe detector for gamma-ray spectrometry and cross section values were determined. As a result excitation functions for the formation of 117mSn, 117m,gIn, 116mIn, 115mIn and 115m,gCd from enriched 116Cd were deduced and compared with the available literature data and with the results of the nuclear reaction model code calculations EMPIRE 3.2 and TALYS 1.8. Yield curves were also deduced for the measured nuclear reactions and compared with the literature.

  6. Light Stable Isotopes in Aquifers Affected by Mining Activities in a Brazilian Mining Province

    NASA Astrophysics Data System (ADS)

    Moreira, R. M.; de Carvalho, J. B.

    2013-05-01

    Iron ore is presently a main item in the Brazilian commercial agenda. Large reserves have converted this utility into an important source of export earnings and, secondarily, of raw materials for the domestic industry. Parallel to a boom in mining activities in the last years environmental impacts and a stress on natural resources have soared. A region exhibiting pronouncedly intensive mining activities lies in the central part of the State of Minas Gerais, the third economy of the federation. Mines are sited right beside the capital and neighbor towns amounting to nearly five million inhabitants and a pronounced dependence on groundwater resources. Besides, this region is a water divide enclosing the sources of main contributors to the most strategic fluvial basins in the country. Iron ore is by large the main mineral but other metals (including gold and uranium), as well as non-metals such as limestone, quartz and granite, also occur. Given the significance of this commodity in the country's trade balance and the demand of water resources with acceptable quality for human consumption, the scale of ensuing water use conflicts caused by its exploration is wide ranging and has to be coped with well grounded environmental assessment approaches. Tracer hydrology techniques might be a valuable tool in this context. The characteristics of the area being impacted have been surveyed, including climate and pluviometry, stratigraphic litology, geological structure, use of soil, mineral resources and their exploration, surface and ground water hydrology and their sundry uses. Data to be processed have been procured at local public agencies but as regard local hydrological features, particularly isotopic compositions, ad hoc surveys and methodologies were required. One instance concerns pluviometric isotopy due to the alpine character of the surveyed region altitude and temperature effects might take place. Hence different sites were monitored; cumulative pluviometer samples

  7. Arctica islandica - a unique paleoclimate archive (growth patterns, light stable isotopes, trace and minor elements)

    NASA Astrophysics Data System (ADS)

    Schone, B. R.; Holland, H. A.; Jochum, K. P.

    2012-12-01

    Shells of long-lived bivalve mollusks are becoming increasingly recognized as powerful paleoclimate archives. Since a decade or so, the ocean quahog, Arctica islandica, is the center of attention. This species inhabits large areas in the northern North Atlantic and can potentially provide the most detailed data ever on extratropical marine paleoclimate variability. Since shell growth is only interrupted for a few months in fall, the full seasonal amplitude of environmental variables is recorded in the shells, e.g. in the form of stable oxygen and carbon isotope values. Moreover, each shell portion can be placed in a precise temporal context by counting annual and, in fast-growing youth portions of the shells, daily increments. Age-detrended annual growth increment time-series of contemporaneous specimens from the same habitat exhibit a large degree of running similarity. Therefore, temporally overlapping time-series can be combined to form even longer chronologies spanning centuries to millennia and many generations of bivalves. Such composite chronologies have been used to reconstruct changes of quasi-decadal to multi-decadal climate variability during the late Holocene. Another heap of environmental information is locked in the shell chemistry, but often superimposed by vital effects. This presentation will provide a brief overview of important findings, present a new 1,040-yr long composite chronology from the North Sea based on 33 specimens and highlight some of the challenges involved with the trace and minor element chemistry of this species.

  8. Titanium-44 and Light Sulfur in Presolar Silicon Carbide Grains with Heavy Silicon: Proof of a Supernova Origin

    NASA Astrophysics Data System (ADS)

    Hoppe, P.; Fujiya, W.

    2011-03-01

    We report here on C, Mg-Al, Si, S, and Ca-Ti isotope measurements on presolar SiC grains with heavy Si. Heavy Si together with light S and large excesses in 44Ca, resulting from in situ decay of 44Ti, are a proof for a SN origin of these grains.

  9. Magic nucleus 132Sn and its one-neutron-hole neighbor 131Sn.

    PubMed

    Bhattacharyya, P; Daly, P J; Zhang, C T; Grabowski, Z W; Saha, S K; Broda, R; Fornal, B; Ahmad, I; Seweryniak, D; Wiedenhöver, I; Carpenter, M P; Janssens, R V; Khoo, T L; Lauritsen, T; Lister, C J; Reiter, P; Blomqvist, J

    2001-08-01

    Prompt and delayed gamma-ray cascades in doubly magic 132Sn and its neighbor 131Sn have been studied at Gammasphere using a 248Cm fission source. Isotopic assignments of unknown gamma rays were based on coincidences with known transitions in A = 112-116 Pd fission partners. The yrast level spectra of both tin nuclei are interpreted using empirical nucleon-nucleon interactions from the 132Sn and 208Pb regions. Results include identification of the (nuf(7/2)h(-1)(11/2))9(+) aligned state in 132Sn and of extensive (nuf(7/2)h(-2)(11/2)), (nuf(7/2)d(-1)(3/2)h(-1)(11/2)) and (nuh(-1)(11/2)x3(-)) multiplets in 131Sn. The previously reported beta(-) decay of an unusual 131In high-spin isomer to levels in 131Sn is also elucidated. PMID:11497825

  10. Muon capture on light isotopes measured with the Double Chooz detector

    NASA Astrophysics Data System (ADS)

    Abe, Y.; Abrahão, T.; Almazan, H.; Alt, C.; Appel, S.; Barriere, J. C.; Baussan, E.; Bekman, I.; Bergevin, M.; Bezerra, T. J. C.; Bezrukov, L.; Blucher, E.; Brugière, T.; Buck, C.; Busenitz, J.; Cabrera, A.; Camilleri, L.; Carr, R.; Cerrada, M.; Chauveau, E.; Chimenti, P.; Collin, A. P.; Conover, E.; Conrad, J. M.; Crespo-Anadón, J. I.; Crum, K.; Cucoanes, A. S.; Damon, E.; Dawson, J. V.; de Kerret, H.; Dhooghe, J.; Dietrich, D.; Djurcic, Z.; dos Anjos, J. C.; Dracos, M.; Etenko, A.; Fallot, M.; Felde, J.; Fernandes, S. M.; Fischer, V.; Franco, D.; Franke, M.; Furuta, H.; Gil-Botella, I.; Giot, L.; Göger-Neff, M.; Gomez, H.; Gonzalez, L. F. G.; Goodenough, L.; Goodman, M. C.; Haag, N.; Hara, T.; Haser, J.; Hellwig, D.; Hofmann, M.; Horton-Smith, G. A.; Hourlier, A.; Ishitsuka, M.; Jochum, J.; Jollet, C.; Kaether, F.; Kalousis, L. N.; Kamyshkov, Y.; Kaneda, M.; Kaplan, D. M.; Kawasaki, T.; Kemp, E.; Kryn, D.; Kuze, M.; Lachenmaier, T.; Lane, C. E.; Lasserre, T.; Letourneau, A.; Lhuillier, D.; Lima, H. P.; Lindner, M.; López-Castaño, J. M.; LoSecco, J. M.; Lubsandorzhiev, B.; Lucht, S.; Maeda, J.; Mariani, C.; Maricic, J.; Martino, J.; Matsubara, T.; Mention, G.; Meregaglia, A.; Miletic, T.; Milincic, R.; Minotti, A.; Nagasaka, Y.; Navas-Nicolás, D.; Novella, P.; Oberauer, L.; Obolensky, M.; Onillon, A.; Osborn, A.; Palomares, C.; Pepe, I. M.; Perasso, S.; Porta, A.; Pronost, G.; Reichenbacher, J.; Reinhold, B.; Röhling, M.; Roncin, R.; Rybolt, B.; Sakamoto, Y.; Santorelli, R.; Schilithz, A. C.; Schönert, S.; Schoppmann, S.; Shaevitz, M. H.; Sharankova, R.; Shrestha, D.; Sibille, V.; Sinev, V.; Skorokhvatov, M.; Smith, E.; Soiron, M.; Spitz, J.; Stahl, A.; Stancu, I.; Stokes, L. F. F.; Strait, M.; Suekane, F.; Sukhotin, S.; Sumiyoshi, T.; Sun, Y.; Svoboda, R.; Terao, K.; Tonazzo, A.; Trinh Thi, H. H.; Valdiviesso, G.; Vassilopoulos, N.; Veyssiere, C.; Vivier, M.; von Feilitzsch, F.; Wagner, S.; Walsh, N.; Watanabe, H.; Wiebusch, C.; Wurm, M.; Yang, G.; Yermia, F.; Zimmer, V.; Double Chooz Collaboration

    2016-05-01

    Using the Double Chooz detector, designed to measure the neutrino mixing angle θ13, the products of μ- capture on 12C,13C,14N, and 16O have been measured. Over a period of 489.5 days, 2.3 ×106 stopping cosmic μ- have been collected, of which 1.8 ×105 captured on carbon, nitrogen, or oxygen nuclei in the inner detector scintillator or acrylic vessels. The resulting isotopes were tagged using prompt neutron emission (when applicable), the subsequent β decays, and, in some cases, β -delayed neutrons. The most precise measurement of the rate of 12C(μ-,ν ) 12B to date is reported: 6 .57-0.21+0.11×103s-1 , or (17 .35-0.59+0.35)% of nuclear captures. By tagging excited states emitting γ s , the ground state transition rate to 12B has been determined to be 5 .68-0.23+0.14 ×103s-1 . The heretofore unobserved reactions 12C(μ-,ν α ) 8Li,13C(μ-,ν n α ) 8Li , and 13C(μ-,ν n ) 12B are measured. Further, a population of β n decays following stopping muons is identified with 5.5 σ significance. Statistics limit our ability to identify these decays definitively. Assuming negligible production of 8He, the reaction 13C(μ-,ν α ) 9Li is found to be present at the 2.7 σ level. Limits are set on a variety of other processes.

  11. On strontium isotopic anomalies and odd-A p-process abundances. [in solar system

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1978-01-01

    Several aspects of the nucleosynthesis of Sr isotopes are considered in an attempt to shed light on the problem of the Sr isotopic anomalies discovered in an inclusion of the Allende meteorite. Decomposition of the Sr isotopes into average r-, s-, and p-process nucleosynthetic classes is performed. It is suggested that the Allende inclusion most likely has an excess of s-process Sr and that the initial Sr-87/Sr-86 isotopic ratio is probably slightly more primitive than basaltic achondrites. The results also show that Sn-115 is mostly due to the r-process and that odd-A yields are very small. It is concluded that if the Sr anomaly in the inclusion is an average s enhancement, it argues somewhat in favor of a model of gas/dust fractionation of s and r isotopes during accumulation of the inclusion parent in the protosolar cloud.

  12. Structural change induced by thermal annealing of red-light-emitting ZnSnF6 • 6H2O:Mn4+ hexahydrate phosphor

    NASA Astrophysics Data System (ADS)

    Hoshino, Ryosuke; Nakamura, Toshihiro; Adachi, Sadao

    2016-05-01

    Effects of thermal annealing on the red-emitting ZnSnF6 • 6H2O:Mn4+ hexahydrate phosphor properties were investigated using X-ray diffraction measurement (XRD), photoluminescence (PL) analysis, and Raman scattering spectroscopy. Thermal annealing was performed at T a = 50 to 400 °C in air for 1 h. Mn4+-related red emission wavelengths were redshifted about 5 nm after annealing at T a ≥ 200 °C with greatly decreased emission intensities. This change in PL spectral feature was attributed to the dehydration of the hexahydrate phosphor, supported by the XRD and Raman scattering results. The XRD and PL intensity analyses determined thermal decomposition energies of ˜0.3 eV from the ZnSnF6 • 6H2O hexahydrate to anhydrate and of ˜0.9 eV from the ZnSnF6 anhydrate to metallic fluorid/oxide (ZnF2/SnO2). A comparative discussion was given on the PL properties of two different Mn4+-activated phosphors, Ba-IV-F6:Mn4+ anhydrate and Zn-IV-F6 • 6H2O:Mn4+ hexahydrate phosphors with IV = Si, Ge, and Sn.

  13. The emission probabilities of long range alpha particles from even-even 244-252Cm isotopes

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Krishnan, Sreejith; Priyanka, B.

    2014-10-01

    The alpha accompanied cold ternary fission of even-even 244Cm, 246Cm, 248Cm, 250Cm and 252Cm isotopes has been studied by taking the interacting barrier as the sum of the Coulomb and proximity potential with the fragments in equatorial configuration. The favorable fragment combinations are obtained from the cold reaction valley plot and by calculating the relative yield for the charge minimized fragments. In the alpha accompanied ternary fission of the 244Cm isotope, the highest yield is found for the fragment combination 110Ru+4He+130Sn, which possess near doubly magic nuclei 130Sn. For the ternary fission of 246Cm, 248Cm, 250Cm and 252Cm isotopes with 4He as the light charged particle, the highest yield is obtained for the fragment combination with doubly magic nuclei 132Sn as the heavier fragment. The emission probabilities and kinetic energies of long range alpha particles have been computed for the 242,244,246,248Cm isotopes and are found to be in good agreement with the experimental data. The relative yields for the 4He accompanied ternary fission (equatorial and collinear) of 242-252Cm isotopes are compared with the corresponding yield for binary fission. The effect of deformation and orientation of fragments in the 4He accompanied ternary fission of 244-252Cm isotopes are studied. Our study reveals that the ground state deformation has as an important role in the alpha accompanied ternary fission as that of the shell effect.

  14. A Luminous Peculiar Type Ia Supernova SN 2011hr: More Like SN 1991T or SN 2007if?

    NASA Astrophysics Data System (ADS)

    Zhang, Ju-Jia; Wang, Xiao-Feng; Sasdelli, Michele; Zhang, Tian-Meng; Liu, Zheng-Wei; Mazzali, Paolo A.; Meng, Xiang-Cun; Maeda, Keiichi; Chen, Jun-Cheng; Huang, Fang; Zhao, Xu-Lin; Zhang, Kai-Cheng; Zhai, Qian; Pian, Elena; Wang, Bo; Chang, Liang; Yi, Wei-Min; Wang, Chuan-Jun; Wang, Xue-Li; Xin, Yu-Xin; Wang, Jian-Guo; Lun, Bao-Li; Zheng, Xiang-Ming; Zhang, Xi-Liang; Fan, Yu-Feng; Bai, Jin-Ming

    2016-02-01

    Photometric and spectroscopic observations of a slowly declining, luminous Type Ia supernova (SN Ia) SN 2011hr in the starburst galaxy NGC 2691 are presented. SN 2011hr is found to peak at {M}B\\=\\-19.84+/- 0.40 {mag}, with a postmaximum decline rate Δm15(B) = 0.92 ± 0.03 mag. From the maximum-light bolometric luminosity, L\\=\\(2.30+/- 0.90)× {10}43 {erg} {{{s}}}-1, we estimate the mass of synthesized 56Ni in SN 2011hr to be M{(}56{Ni})\\=\\1.11+/- 0.43 {M}⊙ . SN 2011hr appears more luminous than SN 1991T at around maximum light, and the absorption features from its intermediate-mass elements (IMEs) are noticeably weaker than those of the latter at similar phases. Spectral modeling suggests that SN 2011hr has IMEs of ˜0.07 {M}⊙ in the outer ejecta, which is much lower than the typical value of normal SNe Ia (i.e., 0.3-0.4 {M}⊙ ) and is also lower than the value of SN 1991T (i.e., ˜0.18 {M}⊙ ). These results indicate that SN 2011hr may arise from a Chandrasekhar-mass white dwarf progenitor that experienced a more efficient burning process in the explosion. Nevertheless, it is still possible that SN 2011hr may serve as a transitional object connecting the SN 1991T-like SNe Ia with a superluminous subclass like SN 2007if given that the latter also shows very weak IMEs at all phases.

  15. A Luminous Peculiar Type Ia Supernova SN 2011hr: More Like SN 1991T or SN 2007if?

    NASA Astrophysics Data System (ADS)

    Zhang, Ju-Jia; Wang, Xiao-Feng; Sasdelli, Michele; Zhang, Tian-Meng; Liu, Zheng-Wei; Mazzali, Paolo A.; Meng, Xiang-Cun; Maeda, Keiichi; Chen, Jun-Cheng; Huang, Fang; Zhao, Xu-Lin; Zhang, Kai-Cheng; Zhai, Qian; Pian, Elena; Wang, Bo; Chang, Liang; Yi, Wei-Min; Wang, Chuan-Jun; Wang, Xue-Li; Xin, Yu-Xin; Wang, Jian-Guo; Lun, Bao-Li; Zheng, Xiang-Ming; Zhang, Xi-Liang; Fan, Yu-Feng; Bai, Jin-Ming

    2016-02-01

    Photometric and spectroscopic observations of a slowly declining, luminous Type Ia supernova (SN Ia) SN 2011hr in the starburst galaxy NGC 2691 are presented. SN 2011hr is found to peak at {M}B\\=\\-19.84+/- 0.40 {mag}, with a postmaximum decline rate Δm15(B) = 0.92 ± 0.03 mag. From the maximum-light bolometric luminosity, L\\=\\(2.30+/- 0.90)× {10}43 {erg} {{{s}}}-1, we estimate the mass of synthesized 56Ni in SN 2011hr to be M{(}56{Ni})\\=\\1.11+/- 0.43 {M}ȯ . SN 2011hr appears more luminous than SN 1991T at around maximum light, and the absorption features from its intermediate-mass elements (IMEs) are noticeably weaker than those of the latter at similar phases. Spectral modeling suggests that SN 2011hr has IMEs of ∼0.07 {M}ȯ in the outer ejecta, which is much lower than the typical value of normal SNe Ia (i.e., 0.3–0.4 {M}ȯ ) and is also lower than the value of SN 1991T (i.e., ∼0.18 {M}ȯ ). These results indicate that SN 2011hr may arise from a Chandrasekhar-mass white dwarf progenitor that experienced a more efficient burning process in the explosion. Nevertheless, it is still possible that SN 2011hr may serve as a transitional object connecting the SN 1991T-like SNe Ia with a superluminous subclass like SN 2007if given that the latter also shows very weak IMEs at all phases.

  16. Lighting.

    SciTech Connect

    United States. Bonneville Power Administration.

    1992-09-01

    Since lighting accounts for about one-third of the energy used in commercial buildings, there is opportunity to conserve. There are two ways to reduce lighting energy use: modify lighting systems so that they used less electricity and/or reduce the number of hours the lights are used. This booklet presents a number of ways to do both. Topics covered include: reassessing lighting levels, reducing lighting levels, increasing bulb & fixture efficiency, using controls to regulate lighting, and taking advantage of daylight.

  17. Quality assurance and quality control in light stable isotope laboratories: a case study of Rio Grande, Texas, water samples.

    PubMed

    Coplen, Tyler B; Qi, Haiping

    2009-06-01

    New isotope laboratories can achieve the goal of reporting the same isotopic composition within analytical uncertainty for the same material analysed decades apart by (1) writing their own acceptance testing procedures and putting them into their mass spectrometric or laser-based isotope-ratio equipment procurement contract, (2) requiring a manufacturer to demonstrate acceptable performance using all sample ports provided with the instrumentation, (3) for each medium to be analysed, prepare two local reference materials substantially different in isotopic composition to encompass the range in isotopic composition expected in the laboratory and calibrated them with isotopic reference materials available from the International Atomic Energy Agency (IAEA) or the US National Institute of Standards and Technology (NIST), (4) using the optimum storage containers (for water samples, sealing in glass ampoules that are sterilised after sealing is satisfactory), (5) interspersing among sample unknowns local laboratory isotopic reference materials daily (internationally distributed isotopic reference materials can be ordered at three-year intervals, and can be used for elemental analyser analyses and other analyses that consume less than 1 mg of material) - this process applies to H, C, N, O, and S isotope ratios, (6) calculating isotopic compositions of unknowns by normalising isotopic data to that of local reference materials, which have been calibrated to internationally distributed isotopic reference materials, (7) reporting results on scales normalised to internationally distributed isotopic reference materials (where they are available) and providing to sample submitters the isotopic compositions of internationally distributed isotopic reference materials of the same substance had they been analysed with unknowns, (8) providing an audit trail in the laboratory for analytical results - this trail commonly will be in electronic format and might include a laboratory

  18. Quality assurance and quality control in light stable isotope laboratories: a case study of Rio Grande, Texas, water samples.

    PubMed

    Coplen, Tyler B; Qi, Haiping

    2009-06-01

    New isotope laboratories can achieve the goal of reporting the same isotopic composition within analytical uncertainty for the same material analysed decades apart by (1) writing their own acceptance testing procedures and putting them into their mass spectrometric or laser-based isotope-ratio equipment procurement contract, (2) requiring a manufacturer to demonstrate acceptable performance using all sample ports provided with the instrumentation, (3) for each medium to be analysed, prepare two local reference materials substantially different in isotopic composition to encompass the range in isotopic composition expected in the laboratory and calibrated them with isotopic reference materials available from the International Atomic Energy Agency (IAEA) or the US National Institute of Standards and Technology (NIST), (4) using the optimum storage containers (for water samples, sealing in glass ampoules that are sterilised after sealing is satisfactory), (5) interspersing among sample unknowns local laboratory isotopic reference materials daily (internationally distributed isotopic reference materials can be ordered at three-year intervals, and can be used for elemental analyser analyses and other analyses that consume less than 1 mg of material) - this process applies to H, C, N, O, and S isotope ratios, (6) calculating isotopic compositions of unknowns by normalising isotopic data to that of local reference materials, which have been calibrated to internationally distributed isotopic reference materials, (7) reporting results on scales normalised to internationally distributed isotopic reference materials (where they are available) and providing to sample submitters the isotopic compositions of internationally distributed isotopic reference materials of the same substance had they been analysed with unknowns, (8) providing an audit trail in the laboratory for analytical results - this trail commonly will be in electronic format and might include a laboratory

  19. Quality assurance and quality control in light stable isotope laboratories: A case study of Rio Grande, Texas, water samples

    USGS Publications Warehouse

    Coplen, T.B.; Qi, H.

    2009-01-01

    New isotope laboratories can achieve the goal of reporting the same isotopic composition within analytical uncertainty for the same material analysed decades apart by (1) writing their own acceptance testing procedures and putting them into their mass spectrometric or laser-based isotope-ratio equipment procurement contract, (2) requiring a manufacturer to demonstrate acceptable performance using all sample ports provided with the instrumentation, (3) for each medium to be analysed, prepare two local reference materials substantially different in isotopic composition to encompass the range in isotopic composition expected in the laboratory and calibrated them with isotopic reference materials available from the International Atomic Energy Agency (IAEA) or the US National Institute of Standards and Technology (NIST), (4) using the optimum storage containers (for water samples, sealing in glass ampoules that are sterilised after sealing is satisfactory), (5) interspersing among sample unknowns local laboratory isotopic reference materials daily (internationally distributed isotopic reference materials can be ordered at three-year intervals, and can be used for elemental analyser analyses and other analyses that consume less than 1 mg of material) - this process applies to H, C, N, O, and S isotope ratios, (6) calculating isotopic compositions of unknowns by normalising isotopic data to that of local reference materials, which have been calibrated to internationally distributed isotopic reference materials, (7) reporting results on scales normalised to internationally distributed isotopic reference materials (where they are available) and providing to sample submitters the isotopic compositions of internationally distributed isotopic reference materials of the same substance had they been analysed with unknowns, (8) providing an audit trail in the laboratory for analytical results - this trail commonly will be in electronic format and might include a laboratory

  20. Beta Decay of 101Sn

    SciTech Connect

    Kavatsyuk, O.; Mazzocchi, C.; Janas, Z.; Banu, A.; Batist, L.; Becker, F.; Blazhev, A.; Bruchle, W.; Doring, J.; Faestermann, T.; Gorska, M.; Grawe, H.; Jungclaus, A.; Karny, M.; Kavatsyuk, M.; Klepper, O.; Kirchner, R.; La Commara, M.; Miernik, K.; Mukha, I.; Plettner, C.; Plochocki, A.; Roeckl, E.; Romoli, M.; Rykaczewski, Krzysztof Piotr; Schadel, M.; Schmidt, K.; Schwengner, R.; Zylicz, J.

    2007-01-01

    The {beta} decay of the very neutron-deficient isotope 101Sn was studied at the GSI on-line mass separator using silicon detectors for recording charged particles and germanium detectors for {gamma}-ray spectroscopy. Based on the {beta}-delayed proton data the production cross-section of 101Sn in the 50Cr + 58Ni fusion-evaporation reaction was determined to be about 60nb. The half-life of 101Sn was measured to be 1.9(3)s. For the first time {beta}-delayed {gamma}-rays of 101Sn were tentatively identified, yielding weak evidence for a cascade of 352 and 1065keV transitions in 101In. The results for the 101Sn decay as well as those from previous work on the 103Sn decay are discussed by comparing them to predictions obtained from shell model calculations employing a new interaction in the 88Sr to 132Sn model space.

  1. The effect of pressure, isotopic (H/D) substitution, and other variables on miscibility in polymer-solvent systems. The nature of the demixing process; dynamic light scattering and small angle neutron scattering studies. Final report

    SciTech Connect

    Van Hook, W.A.

    2000-01-01

    A research program examining the effects of pressure, isotope substitution and other variables on miscibility in polymer solvent systems is described. The techniques employed included phase equilibrium measurements and dynamic light scattering and small angle neutron scattering.

  2. Global properties of nuclei from {sup 100}Sn to {sup 132}Sn

    SciTech Connect

    Isakov, V. I.

    2013-07-15

    The paper presents the results of both microscopical and semi-empirical calculations of single-particle characteristics, nuclear binding, and one-nucleon separation energies of nuclei, as well as their root-mean-square radii, energy levels and transition rates in the long chain of Sn isotopes. We consider nuclei from the extremely neutron-deficient {sup 100}Sn up to neutron excess {sup 136}Sn, where the experimental information is available by now. The comprehensive comparison with the experimental data is carried out.

  3. SN 2009E: a faint clone of SN 1987A

    NASA Astrophysics Data System (ADS)

    Pastorello, A.; Pumo, M. L.; Navasardyan, H.; Zampieri, L.; Turatto, M.; Sollerman, J.; Taddia, F.; Kankare, E.; Mattila, S.; Nicolas, J.; Prosperi, E.; San Segundo Delgado, A.; Taubenberger, S.; Boles, T.; Bachini, M.; Benetti, S.; Bufano, F.; Cappellaro, E.; Cason, A. D.; Cetrulo, G.; Ergon, M.; Germany, L.; Harutyunyan, A.; Howerton, S.; Hurst, G. M.; Patat, F.; Stritzinger, M.; Strolger, L.-G.; Wells, W.

    2012-01-01

    Context.1987A-like events form a rare sub-group of hydrogen-rich core-collapse supernovae that are thought to originate from the explosion of blue supergiant stars. Although SN 1987A is the best known supernova, very few objects of this group have been discovered and, hence, studied. Aims: In this paper we investigate the properties of SN 2009E, which exploded in a relatively nearby spiral galaxy (NGC 4141) and that is probably the faintest 1987A-like supernova discovered so far. We also attempt to characterize this subgroup of core-collapse supernovae with the help of the literature and present new data for a few additional objects. Methods: The lack of early-time observations from professional telescopes is compensated by frequent follow-up observations performed by a number of amateur astronomers. This allows us to reconstruct a well-sampled light curve for SN 2009E. Spectroscopic observations which started about 2 months after the supernova explosion, highlight significant differences between SN 2009E and the prototypical SN 1987A. Modelling the data of SN 2009E allows us to constrain the explosion parameters and the properties of the progenitor star, and compare the inferred estimates with those available for the similar SNe 1987A and 1998A. Results: The light curve of SN 2009E is less luminous than that of SN 1987A and the other members of this class, and the maximum light curve peak is reached at a slightly later epoch than in SN 1987A. Late-time photometric observations suggest that SN 2009E ejected about 0.04 M⊙ of 56Ni, which is the smallest 56Ni mass in our sample of 1987A-like events. Modelling the observations with a radiation hydrodynamics code, we infer for SN 2009E a kinetic plus thermal energy of about 0.6 foe, an initial radius of ~7 × 1012 cm and an ejected mass of ~19 M⊙. The photospheric spectra show a number of narrow (v ≈ 1800 km s-1) metal lines, with unusually strong Ba II lines. The nebular spectrum displays narrow emission lines of

  4. Tin isotope fractionation in terrestrial cassiterites

    SciTech Connect

    McNaughton, N.J. ); Rosman, K.J.R. )

    1991-02-01

    The isotopic composition of tin has been measured in a range of cassiterites and pure reagents to assess the extent to which this element is isotopically fractionated in natural processes. Only two samples showed evidence of isotopic fractionation, and it is concluded that natural Sn isotope fractionation is small and uncommon. This feature reflects the world dominance of Sn-oxide ores Sn-sulfide ores, and the highly efficient processes of Sn dissolution and precipitation which negate equilibrium and kinetic fractionation of Sn isotopes, respectively. The two samples which show slight fractionation are a highly purified and cassiterite from the Archaean Greenbushes pegmatite, Western Australia. The latter Sn is 0.15{per thousand} per mass unit heavier than the authors laboratory standard, whereas the former is 0.12{per thousand} per mass unit lighter. Although the cassiterite fractionation is considered to result from natural geological processes, the fractionation of purified Sn may be either natural or relate to the purification process, the fractionation of this magnitude has a negligible effect on the current best estimate of the atomic weight of Sn, but it does place a lower limit on its associated accuracy.

  5. Isotope reference materials

    USGS Publications Warehouse

    Coplen, Tyler B.

    2010-01-01

    Measurement of the same isotopically homogeneous sample by any laboratory worldwide should yield the same isotopic composition within analytical uncertainty. International distribution of light element isotopic reference materials by the International Atomic Energy Agency and the U.S. National Institute of Standards and Technology enable laboratories to achieve this goal.

  6. Provenancing Archaeological Wool Textiles from Medieval Northern Europe by Light Stable Isotope Analysis (δ13C, δ15N, δ2H)

    PubMed Central

    von Holstein, Isabella C. C.; Walton Rogers, Penelope; Craig, Oliver E.; Penkman, Kirsty E. H.; Newton, Jason; Collins, Matthew J.

    2016-01-01

    We investigate the origin of archaeological wool textiles preserved by anoxic waterlogging from seven medieval archaeological deposits in north-western Europe (c. 700–1600 AD), using geospatial patterning in carbon (δ13C), nitrogen (δ15N) and non-exchangeable hydrogen (δ2H) composition of modern and ancient sheep proteins. δ13C, δ15N and δ2H values from archaeological wool keratin (n = 83) and bone collagen (n = 59) from four sites were interpreted with reference to the composition of modern sheep wool from the same regions. The isotopic composition of wool and bone collagen samples clustered strongly by settlement; inter-regional relationships were largely parallel in modern and ancient samples, though landscape change was also significant. Degradation in archaeological wool samples, examined by elemental and amino acid composition, was greater in samples from Iceland (Reykholt) than in samples from north-east England (York, Newcastle) or northern Germany (Hessens). A nominal assignment approach was used to classify textiles into local/non-local at each site, based on maximal estimates of isotopic variability in modern sheep wool. Light element stable isotope analysis provided new insights into the origins of wool textiles, and demonstrates that isotopic provenancing of keratin preserved in anoxic waterlogged contexts is feasible. We also demonstrate the utility of δ2H analysis to understand the location of origin of archaeological protein samples. PMID:27764106

  7. Light induced phase change in Cu{sub 2−x}Zn{sub 1.3}SnS{sub 4} thin films

    SciTech Connect

    Kumar Samji, Sunil; Tiwari, Brajesh; Krishna Surendra, M.; Ramachandra Rao, M. S.

    2014-04-14

    Cu{sub 2}ZnSnS{sub 4} and its alloy based thin film solar cells have shown better photovoltaic performance under Cu-poor and Zn-rich conditions. However, the effect of Cu-stoichiometry on the coexistence of kesterite (KS), stannite and/or partially disordered kesterite (PD-KS) phases and their influence on photovoltaic performance is not clearly understood. Raman studies were carried out on Cu{sub 2−x}Zn{sub 1.3}SnS{sub 4} (x = 0, 0.3, and 0.5) thin films by changing the intensity of the incident laser beam. It was observed that both Cu-stoichiometry and incident laser beam intensity induce a disorder in the system. Disorder induced transformation of KS (I4{sup ¯}) to PD-KS (I4{sup ¯}2m) is explained by Raman studies.

  8. Variation of the light stable isotopes in the superior and inferior grains of rice (Oryza sativa L.) with different geographical origins.

    PubMed

    Chen, Tianjin; Zhao, Yan; Zhang, Weixing; Yang, Shuming; Ye, Zhihua; Zhang, Guoyou

    2016-10-15

    Trying to explore a new research angle to increase the resolution and accessibility of isotopic based traceability technique, light stable isotopes (δ(13)C, δ(15)N, δD and δ(18)O) in the superior (SS) and inferior (IS) grains of a rice cultivar Daohuaxiang were analyzed with relatively limited sample numbers and adjacent sites in Fujin and Wuchang, Heilongjiang Province, PR China. Distribution of δ(13)C, δ(15)N and δ(18)O in the SS and IS grains were found to be different. δ(18)O and δD can discriminate rice cultivation areas. However, δ(13)C and δ(15)N values in Fujin and Wuchang overlapped when the differences between SS and IS were considered, thus δ(13)C and δ(15)N cannot be used to discriminate cultivation areas. This exploratory study indicate the variation of the light stable isotopes in the grains located on different panicle positions could be used to discriminate the geographical origin but still need further systematic consideration and verification.

  9. Variation of the light stable isotopes in the superior and inferior grains of rice (Oryza sativa L.) with different geographical origins.

    PubMed

    Chen, Tianjin; Zhao, Yan; Zhang, Weixing; Yang, Shuming; Ye, Zhihua; Zhang, Guoyou

    2016-10-15

    Trying to explore a new research angle to increase the resolution and accessibility of isotopic based traceability technique, light stable isotopes (δ(13)C, δ(15)N, δD and δ(18)O) in the superior (SS) and inferior (IS) grains of a rice cultivar Daohuaxiang were analyzed with relatively limited sample numbers and adjacent sites in Fujin and Wuchang, Heilongjiang Province, PR China. Distribution of δ(13)C, δ(15)N and δ(18)O in the SS and IS grains were found to be different. δ(18)O and δD can discriminate rice cultivation areas. However, δ(13)C and δ(15)N values in Fujin and Wuchang overlapped when the differences between SS and IS were considered, thus δ(13)C and δ(15)N cannot be used to discriminate cultivation areas. This exploratory study indicate the variation of the light stable isotopes in the grains located on different panicle positions could be used to discriminate the geographical origin but still need further systematic consideration and verification. PMID:27173539

  10. Electronic structure and optical property of p-type Zn-doped SnO2 with Sn vacancy

    NASA Astrophysics Data System (ADS)

    Guipeng, Sun; Jinliang, Yan; Peijiang, Niu; Delan, Meng

    2016-02-01

    The electronic structures and optical properties of intrinsic SnO2, Zn-doped SnO2, SnO2 with Sn vacancy (VSn) and Zn-doped SnO2 with Sn vacancy are explored by using first-principles calculations. Zn-doped SnO2 is a p-type semiconductor material, whose Fermi level shifts into the valence band when Zn atoms substitute Sn atoms, and the unoccupied states on the top of the valence band come from Zn 3d and O 2p states. Sn vacancies increase the relative hole number of Zn-doped SnO2, which results in a possible increase in the conductivity of Zn-doped SnO2. The Zn-doped SnO2 shows distinct visible light absorption, the increased absorption can be seen apparently with the presence of Sn vacancies in the crystal, and the blue-shift of optical spectra can be observed. Project supported by the National Natural Science Foundation of China (No. 10974077) and the Innovation Project of Shandong Graduate Education, China (No. SDYY13093).

  11. On the Sn loss from thin films of the material system Cu-Zn-Sn-S in high vacuum

    SciTech Connect

    Weber, A.; Mainz, R.; Schock, H. W.

    2010-01-15

    In this paper the Sn loss from thin films of the material system Cu-Zn-Sn-S and the subsystems Cu-Sn-S and Sn-S in high vacuum is investigated. A combination of in situ x-ray diffractometry and x-ray fluorescence (XRF) at a synchrotron light source allowed identifying phases, which tend to decompose and evaporate a Sn-containing compound. On the basis of the XRF results a quantification of the Sn loss from the films during annealing experiments is presented. It can be shown that the evaporation rate from the different phases decreases according to the order SnS{yields}Cu{sub 2}SnS{sub 3}{yields}Cu{sub 4}SnS{sub 4}{yields}Cu{sub 2}ZnSnS{sub 4}. The phase SnS is assigned as the evaporating compound. The influence of an additional inert gas component on the Sn loss and on the formation of Cu{sub 2}ZnSnS{sub 4} thin films is discussed.

  12. Premaximum observations of the type Ia SN 1990N

    NASA Technical Reports Server (NTRS)

    Leibundgut, Bruno; Kirshner, Robert P.; Filippenko, Alexei V.; Shields, Joseph C.; Foltz, Craig B.; Phillips, Mark M.; Sonneborn, George

    1991-01-01

    Spectroscopic and photometric observations of SN 1990N were obtained at ultraviolet and optical wavelengths, beginning 14 days before maximum light. The early observations reveal important differences from spectra of SN Ia's around maximum light. Photometry and spectroscopy obtained after maximum show that SN 1990N is a typical SN Ia and that most of the observed differences are due to the early epoch of the observations. The most significant characteristics are (1) the high velocities of Ca and Si up to 22,000 km/s; (2) the presence of Co and Fe 2 weeks before maximum; and (3) the more rapid increase in the UV flux compared to the optical. The most popular models for white dwarf deflagration that have provided the standard interpretation for SN Ia's at maximum light do not reproduce the high velocities of Ca II and Si II lines observed in SN 1990N.

  13. Highly efficient and isotope selective photo-ionization of barium atoms using diode laser and LED light

    NASA Astrophysics Data System (ADS)

    Wang, B.; Zhang, J. W.; Gao, C.; Wang, L. J.

    2011-08-01

    We demonstrated a simple method to photo-ionize barium atoms using 791 nm diode laser together with 310 nm UV LED. It solved the bottle-neck problem of previous method using 791 nm diode laser and 337 nm N2 laser, whose ionization rate was limited by the repetition rate of N2 laser. Compared with previous method, it has advantages of high efficiency together with simple and cheap setups. By tuning the frequency of 791 nm laser to be resonant with the desired isotope, isotope selective photo-ionization has been realized.

  14. Highly efficient and isotope selective photo-ionization of barium atoms using diode laser and LED light.

    PubMed

    Wang, B; Zhang, J W; Gao, C; Wang, L J

    2011-08-15

    We demonstrated a simple method to photo-ionize barium atoms using 791 nm diode laser together with 310 nm UV LED. It solved the bottle-neck problem of previous method using 791 nm diode laser and 337 nm N(2) laser, whose ionization rate was limited by the repetition rate of N(2) laser. Compared with previous method, it has advantages of high efficiency together with simple and cheap setups. By tuning the frequency of 791 nm laser to be resonant with the desired isotope, isotope selective photo-ionization has been realized. PMID:21935008

  15. Electrochemical isotope effect and lithium isotope separation.

    PubMed

    Black, Jay R; Umeda, Grant; Dunn, Bruce; McDonough, William F; Kavner, Abby

    2009-07-29

    A large electrochemical isotopic effect is observed upon the electrodeposition of lithium from solutions of propylene carbonate producing isotopically light metal deposits. The magnitude of fractionation is controlled by the applied overpotential and is largest close to equilibrium. Calculated partition function ratios for tetrahedrally coordinated lithium complexes and metallic lithium predict an equilibrium fractionation close to that measured experimentally.

  16. OBSERVATIONS OF THE M82 SN 2014J WITH THE KILODEGREE EXTREMELY LITTLE TELESCOPE

    SciTech Connect

    Siverd, Robert J.; Stassun, Keivan G.; Pepper, Joshua; Goobar, Ariel

    2015-01-20

    We report observations of the bright M82 supernova 2014J serendipitously obtained with the Kilodegree Extremely Little Telescope (KELT). The supernova (SN) was observed at high cadence for over 100 days, from pre-explosion, to early rise and peak times, through the secondary bump. The high cadence KELT data with high signal-to-noise ratio is completely unique for SN 2014J and for any other SNIa, with the exception of the (yet) unpublished Kepler data. Here, we report determinations of the SN explosion time and peak time. We also report measures of the ''smoothness'' of the light curve on timescales of minutes/hours never before probed, and we use this to place limits on energy produced from short-lived isotopes or inhomogeneities in the explosion or the circumstellar medium. From the non-observation of significant perturbations of the light curves, we derive a 3σ upper limit corresponding to 8.7 × 10{sup 36} erg  s{sup –1} for any such extra sources of luminosity at optical wavelengths.

  17. C4 plants use fluctuating light less efficiently than do C3 plants: a study of growth, photosynthesis and carbon isotope discrimination.

    PubMed

    Kubásek, Jiří; Urban, Otmar; Šantrůček, Jiří

    2013-12-01

    Plants in the field are commonly exposed to fluctuating light intensity, caused by variable cloud cover, self-shading of leaves in the canopy and/or leaf movement due to turbulence. In contrast to C3 plant species, only little is known about the effects of dynamic light (DL) on photosynthesis and growth in C4 plants. Two C4 and two C3 monocot and eudicot species were grown under steady light or DL conditions with equal sum of daily incident photon flux. We measured leaf gas exchange, plant growth and dry matter carbon isotope discrimination to infer CO2 bundle sheath leakiness in C4 plants. The growth of all species was reduced by DL, despite only small changes in steady-state gas exchange characteristics, and this effect was more pronounced in C4 than C3 species due to lower assimilation at light transitions. This was partially attributed to increased bundle sheath leakiness in C4 plants under the simulated lightfleck conditions. We hypothesize that DL leads to imbalances in the coordination of C4 and C3 cycles and increasing leakiness, thereby decreasing the quantum efficiency of photosynthesis. In addition to their other constraints, the inability of C4 plants to efficiently utilize fluctuating light likely contributes to their absence in such environments as forest understoreys.

  18. Coupling of Er light emissions to plasmon modes on In{sub 2}O{sub 3}: Sn nanoparticle sheets in the near-infrared range

    SciTech Connect

    Matsui, Hiroaki Tabata, Hitoshi; Badalawa, Wasanthamala; Nomura, Wataru; Yatsui, Takashi; Ohtsu, Motoichi; Hasebe, Takayuki; Furuta, Shinya

    2014-07-28

    Near-infrared Er photoluminescence (PL) is markedly modified using a plasmonic In{sub 2}O{sub 3}: Sn nanoparticle (NP) sheet. Modeling and optical measurements reveal the presence of different electric fields (E-field) in the NP sheet. The local E-field excited at the interface between the NP sheet and Er-emitting layer of ZnO contributes significantly towards the spectral modifications of Er PL due to matching with the photon energy of Er PL. We also determine the critical temperature for Er PL modifications, which is related to the energy transfer efficiency between Er transition dipoles in ZnO and the plasmon modes on the NP sheet.

  19. Isotopic microanalysis sheds light on the magmatic endmembers feeding volcanic eruptions: The Astroni 6 case study (Campi Flegrei, Italy)

    NASA Astrophysics Data System (ADS)

    Arienzo, I.; D'Antonio, M.; Di Renzo, V.; Tonarini, S.; Minolfi, G.; Orsi, G.; Carandente, A.; Belviso, P.; Civetta, L.

    2015-10-01

    Sr-isotopic microanalysis has been performed on selected minerals from the Campi Flegrei caldera, together with Sr and Nd isotopic ratio determinations on bulk mineral and glass fractions. The aim was a better characterization of the chemically homogeneous, but isotopically distinct magmatic components which fed volcanic eruptions of the caldera over the past 5 ka, in order to enhance our knowledge about one of the most dangerous volcanoes on Earth. Information on the involved magmatic endmembers, unobtainable by analyzing the isotopic composition of whole rock samples and bulk mineral fractions, has been acquired through high-precision determination of 87Sr/86Sr on single crystals and microdrilled mineral powders. We focused our investigations on the products emplaced during the Astroni 6 eruption (4.23 cal ka BP), assumed representative of the expected event in case of renewed volcanic activity in the Campi Flegrei caldera. Data on single crystals and microdrilled mineral powders have been compared with Sr and Nd isotopic compositions of bulk mineral fractions from products emplaced during the whole Astroni activity, which included seven distinct eruptions. The 87Sr/86Sr ratios of single crystals and microdrilled mineral powders are in the 0.7060 to 0.7076 range, much wider than that of bulk mineral fractions, which range from 0.7066 to 0.7076. Moreover, the Sr isotopic ratios are inversely correlated to 143Nd/144Nd. The new data allow us to better define the magmatic endmembers involved in mingling/mixing processes that occurred prior to/during the Astroni activity. One magmatic endmember, characterized by average 87Sr/86Sr ratio of ~ 0.70750, was quite common in the past 15 ka activity of the Campi Flegrei caldera; the other, as evidenced by the isotopic composition of single feldspar and clinopyroxene crystals, is less enriched in radiogenic Sr (87Sr/86Sr ~ 0.70724). The latter is interpreted to represent a new magmatic component that entered the Campi Flegrei

  20. Ancient DNA, Strontium isotopes, and osteological analyses shed light on social and kinship organization of the Later Stone Age

    PubMed Central

    Haak, Wolfgang; Brandt, Guido; de Jong, Hylke N.; Meyer, Christian; Ganslmeier, Robert; Heyd, Volker; Hawkesworth, Chris; Pike, Alistair W. G.; Meller, Harald; Alt, Kurt W.

    2008-01-01

    In 2005 four outstanding multiple burials were discovered near Eulau, Germany. The 4,600-year-old graves contained groups of adults and children buried facing each other. Skeletal and artifactual evidence and the simultaneous interment of the individuals suggest the supposed families fell victim to a violent event. In a multidisciplinary approach, archaeological, anthropological, geochemical (radiogenic isotopes), and molecular genetic (ancient DNA) methods were applied to these unique burials. Using autosomal, mitochondrial, and Y-chromosomal markers, we identified genetic kinship among the individuals. A direct child-parent relationship was detected in one burial, providing the oldest molecular genetic evidence of a nuclear family. Strontium isotope analyses point to different origins for males and children versus females. By this approach, we gain insight into a Late Stone Age society, which appears to have been exogamous and patrilocal, and in which genetic kinship seems to be a focal point of social organization. PMID:19015520

  1. Chemical and light-stable isotope characteristics of waters from the raft river geothermal area and environs, cassia county, idaho; box elder county, Utah

    USGS Publications Warehouse

    Nathenson, M.; Nehring, N.L.; Crosthwaite, E.G.; Harmon, R.S.; Janik, C.; Borthwick, J.

    1982-01-01

    Chemical and light-stable isotope data are presented for water samples from the Raft River geothermal area and environs. On the basis of chemical character, as defined by a trilinear plot of per cent milliequivalents, and light-stable isotope data, the waters in the geothermal area can be divided into waters that have and have not mixed with cold water. The non-mixed waters have essentially a constant value of light-stable isotopes but show a large variation in chloride content. The variation of chloride composition is not the usual pattern for deep geothermal waters, where it is normally assumed that the deep water has a single chloride composition. Different mixed waters also have hot-water sources of varying chloride composition. Plots of chloride values on cross-sections show that water circulation patterns are confused, with non-mixed waters having different chloride concentrations located in close proximity. Three models can explain the characteristics of the deep geothermal water: (1) in addition to near-surface mixing of cold and hot water, there is deep mixing of two hot waters with the same enthalpy and isotopic composition but differing chloride concentrations to produce the range of chloride concentrations found in the deep geothermal water; (2) there is a single deep hot water, and the range of chloride concentrations is produced by the water passing through a zone of highly soluble materials (most likely in the sedimentary section above the basement) in which waters have different residence times or slightly different circulation paths; (3) the varying chloride concentrations in space have been caused by varying chloride concentrations in the deep feed water through time. Some of this older water has not been flushed from the system by the natural discharge. Although one model may seem more plausible than the others, the available data do not rule out any of them. Data for water samples from the Raft River and Jim Sage Mountains show that water from

  2. SILICON CARBIDE GRAINS OF TYPE C PROVIDE EVIDENCE FOR THE PRODUCTION OF THE UNSTABLE ISOTOPE {sup 32}Si IN SUPERNOVAE

    SciTech Connect

    Pignatari, M.; Rauscher, T.; Thielemann, F.-K.; Zinner, E.; Bertolli, M. G.; Trappitsch, R.; Hoppe, P.; Fryer, C.; Herwig, F.; Hirschi, R.; Timmes, F. X.

    2013-07-01

    Carbon-rich grains are observed to condense in the ejecta of recent core-collapse supernovae (SNe) within a year after the explosion. Silicon carbide grains of type X are C-rich grains with isotopic signatures of explosive SN nucleosynthesis have been found in primitive meteorites. Much rarer silicon carbide grains of type C are a special sub-group of SiC grains from SNe. They show peculiar abundance signatures for Si and S, isotopically heavy Si, and isotopically light S, which appear to be in disagreement with model predictions. We propose that C grains are formed mostly from C-rich stellar material exposed to lower SN shock temperatures than the more common type X grains. In this scenario, extreme {sup 32}S enrichments observed in C grains may be explained by the presence of short-lived {sup 32}Si ({tau}{sub 1/2} = 153 yr) in the ejecta, produced by neutron capture processes starting from the stable Si isotopes. No mixing from deeper Si-rich material and/or fractionation of Si from S due to molecular chemistry is needed to explain the {sup 32}S enrichments. The abundance of {sup 32}Si in the grains can provide constraints on the neutron density reached during the SN explosion in the C-rich He shell material. The impact of the large uncertainty of the neutron capture cross sections in the {sup 32}Si region is discussed.

  3. Oxidation of SnO to SnO{sub 2} thin films in boiling water at atmospheric pressure

    SciTech Connect

    Nose, K. Suzuki, A. Y.; Oda, N.; Kamiko, M.; Mitsuda, Y.

    2014-03-03

    We demonstrated that SnO is oxidized to SnO{sub 2} in boiling water. (001)-oriented SnO thin films were pulsed-laser deposited onto a glass substrate. The Sn valence number changed from (II) to (IV) by keeping SnO films in boiling water at atmospheric pressure for 5 h. Optical transparency of the obtained SnO{sub 2} films was greater than 95% in the visible light range. The SnO{sub 2} films possessed an amorphous structure, and exhibited dielectric properties. Atomic force microscopy and Fourier transform infrared spectroscopy revealed granular structures and the existence of –OH groups, which may account for the diffusion of oxidants within the film.

  4. Experimental determination of the Si isotope fractionation factor between liquid metal and liquid silicate

    NASA Astrophysics Data System (ADS)

    Hin, Remco C.; Fitoussi, Caroline; Schmidt, Max W.; Bourdon, Bernard

    2014-02-01

    The conditions of core formation and the abundances of the light elements in Earth's core remain debated. Silicon isotope fractionation provides a tool contributing to this subject. We present experimentally determined Si isotope fractionation factors between liquid metal and liquid silicate at 1450 °C and 1750 °C, which allow calibrating the temperature dependence of Si isotope fractionation. Experiments were performed in a centrifuging piston cylinder at 1 GPa, employing both graphite and MgO capsules. Tin was used to lower the melting temperature of the metal alloys for experiments performed at 1450 °C. Tests reveal that neither Sn nor C significantly affects Si isotope fractionation. An alkaline fusion technique was employed to dissolve silicate as well as metal phases prior to ion exchange chemistry and mass spectrometric analysis. The results show that metal is consistently enriched in light isotopes relative to the silicate, yielding average metal-silicate fractionation factors of -1.48±0.08‰ and -1.11±0.14‰ at 1450 °C and 1750 °C, respectively. The temperature dependence of equilibrium Si isotope fractionation between metal and silicate can thus be described as Δ30SiMetal-Silicate=-4.42(±0.05)×106/T2. The Si isotope equilibrium fractionation is thus about 1.7 times smaller than previously proposed on the basis of experiments. A consequence of this smaller fractionation is that the calculated difference between the Si isotope composition of the bulk Earth and that of the bulk silicate Earth generated by core formation is smaller than previously thought. It is therefore increasingly difficult to match the Si isotope composition of the bulk silicate Earth with that of chondrites for metal-silicate equilibration temperatures above ∼2500 K. This suggests that Si isotopes were more sensitive to the early stages of core formation when low oxygen fugacities allowed significant incorporation of Si into metal.

  5. Magnetic susceptibility of SnCr, SnMn, SnFe, SnCo and SnNi

    NASA Astrophysics Data System (ADS)

    Henger, U.; Korn, D.

    1984-11-01

    The initial ac susceptibility χ of vapour condensed Sn films with 3d transition metals is measured in situ. SnMn is a spin glass at concentrations up to 36 at% Mn. Spin glass behaviour in SnCr is only observed after annealing to temperatures between 220 and 300 K. This can be related to crystallization in the amorphous and disordered SnCr. SnFe and SnCo exhibit either temperature independent χ or χ below experimental detection. Above the percolation limit χ is getting large and temperature dependent. That is valid for Sn with 30 at% Fe or Co. In Sn films with 50 at% Ni the susceptibility is below the experimental limit.

  6. Dirac neutrinos and SN 1987A

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.

    1991-01-01

    Previous work has shown that the cooling of SN 1987A excludes a Dirac-neutrino mass greater than theta(20 keV) for nu(sub e), nu(sub mu), or nu(sub tau). The emission of wrong-helicity, Dirac neutrinos from SN 1987A, is re-examined. It is concluded that the effect of a Dirac neutrino on the cooling of SN 1987A has been underestimated due to neutrino degeneracy and additional emission processes. The limit that follows from the cooling of SN 1987A is believed to be greater (probably much greater) than 10 keV. This result is significant in light of the recent evidence for a 17 keV mass eigenstate that mixes with the electron neutrino.

  7. Laser isotope separation

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Boyer, Keith; Greiner, Norman R.

    1988-01-01

    A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

  8. Photochemical isotope separation

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

    1987-01-01

    A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

  9. Photochemical isotope separation

    DOEpatents

    Robinson, C.P.; Jensen, R.J.; Cotter, T.P.; Greiner, N.R.; Boyer, K.

    1987-04-28

    A process is described for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium. 8 figs.

  10. Laser isotope separation

    DOEpatents

    Robinson, C.P.; Reed, J.J.; Cotter, T.P.; Boyer, K.; Greiner, N.R.

    1975-11-26

    A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light is described. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

  11. SN 2009ip and SN 2010mc: core-collapse Type IIn supernovae arising from blue supergiants

    NASA Astrophysics Data System (ADS)

    Smith, Nathan; Mauerhan, Jon C.; Prieto, Jose L.

    2014-02-01

    The recent supernova (SN) known as SN 2009ip had dramatic precursor eruptions followed by an even brighter explosion in 2012. Its pre-2012 observations make it the best documented SN progenitor in history, but have fuelled debate about the nature of its 2012 explosion - whether it was a true SN or some type of violent non-terminal event. Both could power shock interaction with circumstellar material (CSM), but only a core-collapse SN provides a self-consistent explanation. The persistent broad emission lines in the spectrum require a relatively large ejecta mass, and a corresponding kinetic energy of at least 1051 erg, while the faint 2012a event is consistent with published models of core-collapse SNe from compact (˜60 R⊙) blue supergiants. The light curves of SN 2009ip and another Type IIn, SN 2010mc, were nearly identical; we demonstrate that their spectra match as well, and that both are standard SNe IIn. Our observations contradict the recent claim that the late-time spectrum of SN 2009ip is returning to its progenitor's luminous blue variable-like state, and we show the that late-time spectra of SN 2009ip closely resemble the spectra of SN 1987A. Moreover, SN 2009ip's changing Hα equivalent width after explosion matches behaviour typically seen in core-collapse SNe IIn. Several key facts about SN 2009ip and SN 2010mc argue strongly in favour of a core-collapse interpretation, and make a non-terminal 1050 erg event implausible. The most straightforward and self-consistent interpretation is that SN 2009ip was an initially faint core-collapse explosion of a blue supergiant that produced about half as much 56Ni as SN 1987A, with most of the peak luminosity from CSM interaction.

  12. Understanding Titan's Atmospheric Isotope Inventory through Laboratory Photolysis Experiments using Vacuum Ultraviolet Photons from Advanced Light Source Synchrotron

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.

    2015-12-01

    Titan, Saturn's planet-like moon with a thick atmosphere consists mainly of N2 (98.4 %) and CH4 (1.4%). It is debated whether the N2 is primordial, or the NH3, which later converted to N2 by physic-chemical processes and, if NH3 is primordial, what is the source of that material: Saturnian-subnebula or the comets? N2 is enriched in 15N (14N/15N = 160 compared to 272 for Earth) and in geochemical terminology, d15Nair = 700 ‰ (parts per thousand with respect to ambient air). On the same scale the solar wind and Jupiter's atmosphere are ~ -400 ‰ (depleted in 15N). The comets (NH3 and HCN) and insoluble organic matter in meteorites are also enriched in 15N in the range up to a few thousand ‰. On the contrary, the carbon isotopic ratio in CH4 in Titan is similar to the other solar system bodies (12C/13C~ 89). We have performed extensive low temperature (80 K) photodissociation of N2 and CO (in presence of H2) at VUV wavelengths to measure the isotopic fractionation in the products. The integrated instantaneous fractionation in the product NH3 is about 1000 ‰ over the N2 dissociation regime (80-100 nm), which arise due to quantum mechanical selection rules. CO2 and CH4, the products of CO photodissociation, show contradictory results for two elements. While product O (trapped in CO2) is enriched by few thousand ‰, there is no significant C isotopic enrichment in CH4. These laboratory measurements along with the measurements by Cassini-Huygens spacecraft constrain the origin of volatiles in Titan's atmosphere and indicate that Titan accreted comet-like NH3 and CH4, which are the 1st generation photolysis products (of the remaining materials after the formation of gas giants) in the solar nebula. Later, NH3 converted to N2 in a bulk fashion (within Titan) and retained mostly identical isotopic composition. 15N enrichment measured in HCN in the present day atmosphere (d15Nair > 1500 ‰), is possibly from the 2nd generation N2 photolysis in Titan's modern

  13. An episode of widespread ocean anoxia during the latest Ediacaran Period revealed by light U isotope compositions in carbonates

    NASA Astrophysics Data System (ADS)

    Zhang, F.

    2015-12-01

    Reconstruction of ocean redox chemistry during the Ediacaran Period is important for understanding the causal relationship between environmental oxygen levels and early metazoan evolution. Geochemical data (e.g., high Mo and U concentrations and/or heavy Mo and U isotope compositions from sedimentary rocks) provide evidence of extensive ocean oxygenation shortly after the Marinoan glaciation at ca. 632 Ma [1], during the late Ediacaran Period at ca. 560-551 Ma [2], and multiple times during the early Cambrian Period [3, 4]. These episodes of oxygenation may have been separated by intervals of less oxygenated conditions [1, 2]. However, the global redox state of the ocean during the terminal Ediacaran period (ca. 551-541 Ma) is poorly constrained. We address this knowledge gap by measuring carbonate U isotope compositions (δ238U) - a novel global ocean redox proxy - of the Gaojiashan Member of the late Ediacaran Dengying Formation (ca. 551-541 Ma) in South China. An abrupt negative shift in δ238U from values scattering around -0.45‰ to values averaging -0.95‰ (±0.20‰, 2sd) was observed in the middle Gaojiashan Member, suggesting a globally widespread expansion of ocean anoxia during the terminal Ediacaran Period. The negative δ238U shift coincides with the onset of a pronounced positive carbon isotope excursion (from 0‰ to +6‰), suggesting that ocean anoxia is the major driving force behind enhanced organic carbon burial that led to the carbon isotope excursion. The widespread anoxia recorded by the Gaojiashan Member is bracketed by known intervals of extensive ocean oxygenation, thus indicating that the Precambrian-Phanerozoic transition was characterized by oscillating ocean redox conditions. The Ediacara biota (ca. 541 Ma) [5] disappeared shortly after the widespread ocean anoxia, suggesting that an expansion of ocean anoxia may have triggerred the onset of a mass extinction in the latest Ediacaran time. References: [1] Sahoo, et al. (2012), Nature

  14. Fabrication of cubic Zn2SnO4/SnO2 complex hollow structures and their sunlight-driven photocatalytic activity.

    PubMed

    Sun, Linqiang; Han, Xiao; Jiang, Zhe; Ye, Tingting; Li, Rong; Zhao, Xinsheng; Han, Xiguang

    2016-06-30

    Uniform hollow, yolk-shell and double-shell Zn2SnO4/SnO2 nanoparticles with cubic morphologies have been synthesized using "etching-second growth-annealed" methods. Due to the high light-harvesting efficiency and low recombination rate of the photo-generated electron-hole pair, double-shell structures of Zn2SnO4/SnO2 nanoparticles show an obvious improvement in photocatalytic activity.

  15. Photo and electroluminescence of ZnSe: Sn and ZnSe:(Sn, Pr) phosphors

    NASA Astrophysics Data System (ADS)

    Mishra, A. K.; Mishra, S. K.; Pandey, S. P.; Lakshmi Mishra, Kshama

    2016-09-01

    We have prepared ZnSe (luminescent grade) phosphor doped with Sn and (Sn,Pr) with varying concentration in an inert atmosphere in a silica tubular furnace at temperature of (780 ± 20) °C for 1 hr to obtain ZnSe:Sn and ZnSe: (Sn,Pr) phosphors. The photo luminescence (PL) and electroluminescence (EL) spectra of these phosphors have been studied at room temperature and results were discussed in the light of existing models. Dependence of EL emission on the voltage frequency has also been carried out. It is found that the plot between the integrated light intensity versus 1/√Vrms is a straight line suggesting the existence of Mott-Schottky type barrier on the metal semiconductor interface.

  16. Spectrum synthesis of the Type Ia supernovae SN 1992A and SN 1981B

    NASA Technical Reports Server (NTRS)

    Nugent, Peter; Baron, E.; Hauschildt, Peter H.; Branch, David

    1995-01-01

    We present non-local thermodynamic equilibrium (non-LTE) synthetic spectra for the Type Ia supernovae SN 1992A and SN 1981B, near maximum light. At this epoch both supernovae were observed from the UV through the optical. This wide spectral coverage is essential for determining the density structure of a SN Ia. Our fits are in good agreement with observation and provide some insight as to the differences between these supernovae. We also discuss the application of the expanding photosphere method to SNe Ia which gives a distance that is independent of those based on the decay of Ni-56 and Cepheid variable stars.

  17. Anaerobic Central Metabolic Pathways in Shewanella oneidensis MR-1 Reinterpreted in the Light of Isotopic Metabolite Labeling▿

    PubMed Central

    Tang, Yinjie J.; Meadows, Adam L.; Kirby, James; Keasling, Jay D.

    2007-01-01

    It has been proposed that during growth under anaerobic or oxygen-limited conditions, Shewanella oneidensis MR-1 uses the serine-isocitrate lyase pathway common to many methylotrophic anaerobes, in which formaldehyde produced from pyruvate is condensed with glycine to form serine. The serine is then transformed through hydroxypyruvate and glycerate to enter central metabolism at phosphoglycerate. To examine its use of the serine-isocitrate lyase pathway under anaerobic conditions, we grew S. oneidensis MR-1 on [1-13C]lactate as the sole carbon source, with either trimethylamine N-oxide (TMAO) or fumarate as an electron acceptor. Analysis of cellular metabolites indicated that a large percentage (>70%) of lactate was partially oxidized to either acetate or pyruvate. The 13C isotope distributions in amino acids and other key metabolites indicate that under anaerobic conditions, although glyoxylate synthesized from the isocitrate lyase reaction can be converted to glycine, a complete serine-isocitrate pathway is not present and serine/glycine is, in fact, oxidized via a highly reversible degradation pathway. The labeling data also suggest significant activity in the anapleurotic (malic enzyme and phosphoenolpyruvate carboxylase) reactions. Although the tricarboxylic acid (TCA) cycle is often observed to be incomplete in many other anaerobes (absence of 2-oxoglutarate dehydrogenase activity), isotopic labeling supports the existence of a complete TCA cycle in S. oneidensis MR-1 under certain anaerobic conditions, e.g., TMAO-reducing conditions. PMID:17114268

  18. Band structure in 113Sn

    NASA Astrophysics Data System (ADS)

    Banerjee, P.; Ganguly, S.; Pradhan, M. K.; Sharma, H. P.; Muralithar, S.; Singh, R. P.; Bhowmik, R. K.

    2016-07-01

    The structure of collective bands in 113Sn, populated in the reaction 100Mo(19F,p 5 n ) at a beam energy of 105 MeV, has been studied. A new positive-parity sequence of eight states extending up to 7764.9 keV and spin (39 /2+) has been observed. The band is explained as arising from the coupling of the odd valence neutron in the g7 /2 or the d5 /2 orbital to the deformed 2p-2h proton configuration of the neighboring even-A Sn isotope. Lifetimes of six states up to an excitation energy of 9934.9 keV and spin 47 /2-belonging to a Δ I =2 intruder band have been measured for the first time, including an upper limit for the last state, from Doppler-shift-attenuation data. A moderate average quadrupole deformation β2=0.22 ±0.02 is deduced from these results for the five states up to spin 43 /2- . The transition quadrupole moments decrease with increase in rotational frequency, indicating a reduction of collectivity with spin, a feature common for terminating bands. The behavior of the kinematic and dynamic moments of inertia as a function of rotational frequency has been studied and total Routhian surface calculations have been performed in an attempt to obtain an insight into the nature of the states near termination.

  19. 0(gs)+ -->2(1)+ transition strengths in 106Sn and 108Sn.

    PubMed

    Ekström, A; Cederkäll, J; Fahlander, C; Hjorth-Jensen, M; Ames, F; Butler, P A; Davinson, T; Eberth, J; Fincke, F; Görgen, A; Górska, M; Habs, D; Hurst, A M; Huyse, M; Ivanov, O; Iwanicki, J; Kester, O; Köster, U; Marsh, B A; Mierzejewski, J; Reiter, P; Scheit, H; Schwalm, D; Siem, S; Sletten, G; Stefanescu, I; Tveten, G M; Van de Walle, J; Van Duppen, P; Voulot, D; Warr, N; Weisshaar, D; Wenander, F; Zielińska, M

    2008-07-01

    The reduced transition probabilities, B(E2; 0(gs)+ -->2(1)+), have been measured in the radioactive isotopes (108,106)Sn using subbarrier Coulomb excitation at the REX-ISOLDE facility at CERN. Deexcitation gamma rays were detected by the highly segmented MINIBALL Ge-detector array. The results, B(E2;0(gs)+ -->2(1)+)=0.222(19)e2b2 for 108Sn and B(E2; 0(gs)+-->2(1)+)=0.195(39)e2b2 for 106Sn were determined relative to a stable 58Ni target. The resulting B(E2) values are approximately 30% larger than shell-model predictions and deviate from the generalized seniority model. This experimental result may point towards a weakening of the N=Z=50 shell closure.

  20. 0gs+→21+ Transition Strengths in Sn106 and Sn108

    NASA Astrophysics Data System (ADS)

    Ekström, A.; Cederkäll, J.; Fahlander, C.; Hjorth-Jensen, M.; Ames, F.; Butler, P. A.; Davinson, T.; Eberth, J.; Fincke, F.; Görgen, A.; Górska, M.; Habs, D.; Hurst, A. M.; Huyse, M.; Ivanov, O.; Iwanicki, J.; Kester, O.; Köster, U.; Marsh, B. A.; Mierzejewski, J.; Reiter, P.; Scheit, H.; Schwalm, D.; Siem, S.; Sletten, G.; Stefanescu, I.; Tveten, G. M.; van de Walle, J.; van Duppen, P.; Voulot, D.; Warr, N.; Weisshaar, D.; Wenander, F.; Zielińska, M.

    2008-07-01

    The reduced transition probabilities, B(E2;0gs+→21+), have been measured in the radioactive isotopes Sn108,106 using subbarrier Coulomb excitation at the REX-ISOLDE facility at CERN. Deexcitation γ rays were detected by the highly segmented MINIBALL Ge-detector array. The results, B(E2;0gs+→21+)=0.222(19)e2b2 for Sn108 and B(E2;0gs+→21+)=0.195(39)e2b2 for Sn106 were determined relative to a stable Ni58 target. The resulting B(E2) values are ˜30% larger than shell-model predictions and deviate from the generalized seniority model. This experimental result may point towards a weakening of the N=Z=50 shell closure.

  1. Lighting

    SciTech Connect

    Audin, L.

    1994-12-31

    EPAct covers a vast territory beyond lighting and, like all legislation, also contains numerous {open_quotes}favors,{close_quotes} compromises, and even some sleight-of-hand. Tucked away under Title XIX, for example, is an increase from 20% to 28% tax on gambling winnings, effective January 1, 1993 - apparently as a way to help pay for new spending listed elsewhere in the bill. Overall, it is a landmark piece of legislation, about a decade overdue. It remains to be seen how the Federal Government will enforce upgrading of state (or even their own) energy codes. There is no mention of funding for {open_quotes}energy police{close_quotes} in EPAct. Merely creating such a national standard, however, provides a target for those who sincerely wish to create an energy-efficient future.

  2. Photometric Monitoring of SN 2011dh

    NASA Astrophysics Data System (ADS)

    Spencer, Michelle E.; Joner, M. D.; Laney, C. D.; Stoker, E.

    2012-01-01

    We present BVRI light curves of SN 2011dh located in the nearby, nearly face-on spiral galaxy M51. The data were secured using the 0.9 m telescope at the West Mountain Observatory. The data span approximately 100 days with the first observations being before maximum light. The shapes of the light curves are well defined and the time of maximum light is well established. Standard Johnson-Cousins filters were utilized for all of the observations and several nights from this data set were standardized using selections of Landolt standards. SN 2011dh has been classified as Type IIb core-collapse supernova. We would like to thank the Brigham Young University College of Physical and Mathematical Sciences for continued support of mentored student research at the West Mountain Observatory. Partial support for this project was derived from NSF grant AST #0618209.

  3. SN 1991bg - A type Ia supernova with a difference

    NASA Technical Reports Server (NTRS)

    Leibundgut, Bruno; Kirshner, Robert P.; Phillips, Mark M.; Wells, Lisa A.; Suntzeff, N. B.; Hamuy, Mario; Schommer, R. A.; Walker, A. R.; Gonzalez, L.; Ugarte, P.

    1993-01-01

    While SN 1991bg is an unusual type Ia SN in such a feature as the brief duration of the photospheric phase, which ended only two weeks after maximum, it shares with other Ia SNs strong Si II and Ca II lines near maximum light. In addition, the light and color curve slopes are almost identical with the templates at late times. The spectral evolution of SN 1991bg is also unique but not unrecognizable; nevertheless, the peculiarities associated with this event complicate the fundamental question as to whether the Ia SNs make good standard candles.

  4. Crystal chemistry of sodium zirconium phosphate based simulated ceramic waste forms of effluent cations (Ba(2+), Sn(4+), Fe(3+), Cr(3+), Ni(2+) and Si(4+)) from light water reactor fuel reprocessing plants.

    PubMed

    Shrivastava, O P; Chourasia, Rashmi

    2008-05-01

    A novel concept of immobilization of light water reactor (LWR) fuel reprocessing waste effluent through interaction with sodium zirconium phosphate (NZP) has been established. Such conversion utilizes waste materials like zirconium and nickel alloys, stainless steel, spent solvent tri-butyl phosphate and concentrated solution of NaNO(3). The resultant multi component NZP material is a physically and chemically stable single phase crystalline product having good mechanical strength. The NZP matrix can also incorporate all types of fission product cations in a stable crystalline lattice structure; therefore, the resultant solid solutions deserve quantification of crystallographic data. In this communication, crystal chemistry of the two types of simulated waste forms (type I-Na(1.49)Zr(1.56)Sn(0.02)Fe(0).(28)Cr(0.07)Ni(0.07)P(3)O(12) and type II-Na(1.35)Ba(0.14)Zr(1.56)Sn(0.02)Fe(0).(28)Cr(0.07)Ni(0.07)P(2.86)Si(0.14)O(12)) has been investigated using General Structure Analysis System (GSAS) programming of the X-ray powder diffraction data. About 4001 data points of each have been subjected to Rietveld analysis to arrive at a satisfactory structural convergence of Rietveld parameters; R-pattern (R(p))=0.0821, R-weighted pattern (R(wp))=0.1266 for type I and R(p)=0.0686, R(wp)=0.0910 for type II. The structure of type I and type II waste forms consist of ZrO(6) octahedra and PO(4) tetrahedra linked by the corners to form a three-dimensional network. Each phosphate group is on a two-fold rotation axis and is linked to four ZrO(6) octahedra while zirconium octahedra lies on a three-fold rotation axis and is connected to six PO(4) tetrahedra. Though the expansion along c-axis and shrinkage along a-axis with slight distortion of bond angles in the synthesized crystal indicate the flexibility of the structure, the waste forms are basically of NZP structure. Morphological examination by SEM reveals that the size of almost rectangular parallelepiped crystallites varies

  5. Temperature-controlled fabrication of SnO2 nanoparticles via thermal heating of Sn powders

    NASA Astrophysics Data System (ADS)

    Kim, H. W.; Shim, S. H.

    2007-09-01

    We report a method by which we have produced nano-sized crystalline tin oxide (SnO2) particles with a rutile structure. We have employed thermal evaporation of solid Sn powders in ambient air. Samples were characterized by scanning electron microscopy, X-ray powder diffraction, transmission electron microscopy, and photoluminescence (PL) spectroscopy. The size of SnO2 particles in an agglomerated state was found to decrease on decreasing the synthesis temperature in the range of 700 850 °C. The product synthesized at a low temperature of 700 °C was comprised of a trace amount of tetragonal SnO phase. Photoluminescence spectra showed visible light emission, with its overall intensity being increased on increasing the synthesis temperature.

  6. Automatic procedure for mass and charge identification of light isotopes detected in CsI(Tl) of the GARFIELD apparatus

    NASA Astrophysics Data System (ADS)

    Morelli, L.; Bruno, M.; Baiocco, G.; Bardelli, L.; Barlini, S.; Bini, M.; Casini, G.; D'Agostino, M.; Degerlier, M.; Gramegna, F.; Kravchuk, V. L.; Marchi, T.; Pasquali, G.; Poggi, G.

    2010-08-01

    Mass and charge identification of light charged particles detected with the 180 CsI(Tl) detectors of the GARFIELD apparatus is presented. A "tracking" method to automatically sample the Z and A ridges of "Fast-Slow" histograms is developed. An empirical analytic identification function is used to fit correlations between Fast and Slow, in order to determine, event by event, the atomic and mass numbers of the detected charged reaction products. A summary of the advantages of the proposed method with respect to "hand-based" procedures is reported.

  7. SnO₂(β-Bi₂O₃)/Bi₂Sn₂O₇ nanohybrids doped with Pt and Pd nanoparticles: applications in visible light photocatalysis, electrical conductivity and dye-sensitized solar cells.

    PubMed

    Khairy, M; Mohamed, Mohamed Mokhtar

    2015-09-01

    Bi2O3-SnO2 nanocomposites formed at a nominal molar ratio of 3 : 1 and loaded with Pd/Pt nanoparticles synthesized by a sol gel-hydrothermal method with the aid of a template were thoroughly characterized by X-ray diffraction, TEM-EDX, N2 sorptiometry, diffuse reflectance UV-Vis, FTIR, photoluminescence and electrical conductivity. It has been shown that Pd and Pt stimulate the existence of β-Bi2O3 and SnO2, respectively together with the key component Bi2Sn2O7. The photocatalytic results indicate that Pd/β-Bi2O3-Bi2Sn2O7 revealed a remarkable performance for the degradation of methylene blue (MB) dye as compared to the Pt/SnO2-Bi2Sn2O7 and Bi2O3-SnO2 samples in both the UV and visible regions. The enhanced photocatalytic activity of the Pd/β-Bi2O3-Bi2Sn2O7 nanocomposite is primarily attributed to the broad contact between the β-Bi2O3 and Bi2Sn2O7 phases, which indicates high mesoporosity and heterojunction structures resulting in separation efficacy between photo-induced electron-hole pairs. Specifically, the photosensitive β-Bi2O3 is easily excited and released electrons to be accepted by Bi2Sn2O7 and Pd that might be deposited in the interlayer between β-Bi2O3 and Bi2Sn2O7. The degradation mechanism of MB over Pd/β-Bi2O3-Bi2Sn2O7 in the visible region showed that the dye degradation proceeds through evolution of ˙O2(-) and ˙OH radicals as evaluated using photoluminescence and free radical trapping experiments. An insight into the electrical properties including the dielectric constant and impedance of the materials indicates that Pd/β-Bi2O3-Bi2Sn2O7 has the highest conductivity based on increasing the ionic transport and defects at the β-Bi2O3/Bi2Sn2O7 heterojunction. This material displayed an improved photocurrent response of a higher power conversion efficiency, exceeding that of Pt/SnO2-Bi2Sn2O7 and SnBi3 by 50% and 250%, respectively, in dye-sensitized solar cells. Picosecond-resolved photoluminescence (PL) and polarization gated PL

  8. Beta-Decay Studies near 100Sn

    SciTech Connect

    Karny, M.; Batist, L.; Banu, A.; Becker, F.; Blazhev, A.; Burkard, K.; Bruchle, W.; Doring, J.; Faestermann, T.; Gorska, M.; Grawe, H.; Janas, Z.; Jungclaus, A.; Kavatsyuk, M.; Kavatsyuk, O.; Kirchner, R.; La Commara, M.; Mandal, S.; Mazzocchi, C.; Miernik, K.; Mukha, I.; Muralithar, S.; Plettner, C.; Plochocki, A.; Roeckl, E.; Romoli, M.; Rykaczewski, Krzysztof Piotr; Schadel, M.; Schmidt, K.; Schwengner, R.; Zylicz, J.

    2005-01-01

    The {beta}-decay of {sup 102}Sn was studied by using high-resolution germanium detectors as well as a Total Absorption Spectrometer (TAS). A decay scheme has been constructed based on the {gamma}-{gamma} coincidence data. The total experimental Gamow-Teller strength B{sub GT}{sup exp} of {sup 102}Sn was deduced from the TAS data to be 4.2(9). A search for {beta}-delayed {gamma}-rays of {sup 100}Sn decay remained unsuccessful. However, a Gamow-Teller hindrance factor h = 2.2(3), and a cross-section of about 3nb for the production of {sup 100}Sn in fusion-evaporation reaction between {sup 58}Ni beam and {sup 50}Cr target have been estimated from the data on heavier tin isotopes. The estimated hindrance factor is similar to the values derived for lower shell nuclei.

  9. SN1987A's Twentieth Anniversary

    NASA Astrophysics Data System (ADS)

    2007-02-01

    Looking back at 20 Years of Observations of this Supernova with ESO telescopes The unique supernova SN 1987A has been a bonanza for astrophysicists. It provided several observational 'firsts,' like the detection of neutrinos from an exploding star, the observation of the progenitor star on archival photographic plates, the signatures of a non-spherical explosion, the direct observation of the radioactive elements produced during the blast, observation of the formation of dust in the supernova, as well as the detection of circumstellar and interstellar material. ESO PR Photo 08a/07 ESO PR Photo 08a/07 SN1987A in the Large Magellanic Cloud Today, it is exactly twenty years since the explosion of Supernova 1987A in the Large Magellanic Cloud was first observed, at a distance of 163,000 light-years. It was the first naked-eye supernova to be seen for 383 years. Few events in modern astronomy have met with such an enthusiastic response by the scientists and now, after 20 years, it continues to be an extremely exciting object that is further studied by astronomers around the world, in particular using ESO's telescopes. When the first signs of Supernova 1987A, the first supernova of the year 1987, were noticed early on 24 February of that year, it was clear that this would be an unusual event. It was discovered by naked-eye and on a panoramic photographic plate taken with a 10-inch astrograph on Las Campanas in Chile by Oscar Duhalde and Ian Shelton, respectively. A few hours earlier, still on 23 February, two large underground detectors - in Japan and the USA - had registered the passage of high-energy neutrinos. Since SN 1987A exploded in the Large Magellanic Cloud (LMC), it was only accessible to telescopes in the Southern Hemisphere, more particularly in Australia, South Africa, and South America. In Chile, ESO's observatory at La Silla with its armada of telescopes with sizes between 0.5 and 3.6-m, played an important role. ESO PR Photo 08c/07 ESO PR Photo 08c/07 The

  10. NEUTRON-RICH CHROMIUM ISOTOPE ANOMALIES IN SUPERNOVA NANOPARTICLES

    SciTech Connect

    Dauphas, N.; Remusat, L.; Papanastassiou, D. A.; Guan, Y.; Ma, C.; Eiler, J. M.; Chen, J. H.; Roskosz, M.; Stodolna, J.

    2010-09-10

    Neutron-rich isotopes with masses near that of iron are produced in Type Ia and II supernovae (SNeIa and SNeII). Traces of such nucleosynthesis are found in primitive meteorites in the form of variations in the isotopic abundance of {sup 54}Cr, the most neutron-rich stable isotope of chromium. The hosts of these isotopic anomalies must be presolar grains that condensed in the outflows of SNe, offering the opportunity to study the nucleosynthesis of iron-peak nuclei in ways that complement spectroscopic observations and can inform models of stellar evolution. However, despite almost two decades of extensive search, the carrier of {sup 54}Cr anomalies is still unknown, presumably because it is fine grained and is chemically labile. Here, we identify in the primitive meteorite Orgueil the carrier of {sup 54}Cr anomalies as nanoparticles (<100 nm), most likely spinels that show large enrichments in {sup 54}Cr relative to solar composition ({sup 54}Cr/{sup 52}Cr ratio >3.6 x solar). Such large enrichments in {sup 54}Cr can only be produced in SNe. The mineralogy of the grains supports condensation in the O/Ne-O/C zones of an SNII, although a Type Ia origin cannot be excluded. We suggest that planetary materials incorporated different amounts of these nanoparticles, possibly due to late injection by a nearby SN that also delivered {sup 26}Al and {sup 60}Fe to the solar system. This idea explains why the relative abundance of {sup 54}Cr and other neutron-rich isotopes vary between planets and meteorites. We anticipate that future isotopic studies of the grains identified here will shed new light on the birth of the solar system and the conditions in SNe.

  11. Temperature varying photoconductivity of GeSn alloys grown by chemical vapor deposition with Sn concentrations from 4% to 11%

    NASA Astrophysics Data System (ADS)

    Hart, John; Adam, Thomas; Kim, Yihwan; Huang, Yi-Chiau; Reznicek, Alexander; Hazbun, Ramsey; Gupta, Jay; Kolodzey, James

    2016-03-01

    Pseudomorphic GeSn layers with Sn atomic percentages between 4.5% and 11.3% were grown by chemical vapor deposition using digermane and SnCl4 precursors on Ge virtual substrates grown on Si. The layers were characterized by x-ray diffraction rocking curves and reciprocal space maps. Photoconductive devices were fabricated, and the dark current was found to increase with Sn concentration. The responsivity of the photoconductors was measured at a wavelength of 1.55 μm using calibrated laser illumination at room temperature and a maximum value of 2.7 mA/W was measured for a 4.5% Sn device. Moreover, the responsivity for higher Sn concentration was found to increase with decreasing temperature. Spectral photoconductivity was measured using Fourier transform infrared spectroscopy. The photoconductive absorption edge continually increased in wavelength with increasing tin percentage, out to approximately 2.4 μm for an 11.3% Sn device. The direct band gap was extracted using Tauc plots and was fit to a bandgap model accounting for layer strain and Sn concentration. This direct bandgap was attributed to absorption from the heavy-hole band to the conduction band. Higher energy absorption was also observed, which was thought to be likely from absorption in the light-hole band. The band gaps for these alloys were plotted as a function of temperature. These experiments show the promise of GeSn alloys for CMOS compatible short wave infrared detectors.

  12. Particle and light fragment emission in peripheral heavy ion collisions at Fermi energies

    SciTech Connect

    Piantelli, S.; Maurenzig, P. R.; Olmi, A.; Bardelli, L.; Bartoli, A.; Bini, M.; Casini, G.; Coppi, C.; Mangiarotti, A.; Pasquali, G.; Poggi, G.; Stefanini, A. A.; Taccetti, N.; Vanzi, E.

    2006-09-15

    A systematic investigation of the average multiplicities of light charged particles and intermediate mass fragments emitted in peripheral and semiperipheral collisions is presented as a function of the beam energy, violence of the collision, and mass of the system. The data have been collected with the FIASCO setup in the reactions {sup 93}Nb+{sup 93}Nb at (17,23,30,38)A MeV and {sup 116}Sn+{sup 116}Sn at (30,38)A MeV. The midvelocity emission has been separated from the emission of the projectile-like fragment. This last component appears to be compatible with an evaporation from an equilibrated source at normal density, as described by the statistical code GEMINI at the appropriate excitation energy. On the contrary, the midvelocity emission presents remarkable differences in both the dependence of the multiplicities on the energy deposited in the midvelocity region and the isotopic composition of the emitted light charged particles.

  13. Particle and light fragment emission in peripheral heavy ion collisions at Fermi energies

    NASA Astrophysics Data System (ADS)

    Piantelli, S.; Maurenzig, P. R.; Olmi, A.; Bardelli, L.; Bartoli, A.; Bini, M.; Casini, G.; Coppi, C.; Mangiarotti, A.; Pasquali, G.; Poggi, G.; Stefanini, A. A.; Taccetti, N.; Vanzi, E.

    2006-09-01

    A systematic investigation of the average multiplicities of light charged particles and intermediate mass fragments emitted in peripheral and semiperipheral collisions is presented as a function of the beam energy, violence of the collision, and mass of the system. The data have been collected with the FIASCO setup in the reactions Nb93+Nb93 at (17,23,30,38)A MeV and Sn116+Sn116 at (30,38)A MeV. The midvelocity emission has been separated from the emission of the projectile-like fragment. This last component appears to be compatible with an evaporation from an equilibrated source at normal density, as described by the statistical code GEMINI at the appropriate excitation energy. On the contrary, the midvelocity emission presents remarkable differences in both the dependence of the multiplicities on the energy deposited in the midvelocity region and the isotopic composition of the emitted light charged particles.

  14. Quantitative Determination of Isotope Ratios from Experimental Isotopic Distributions

    PubMed Central

    Kaur, Parminder; O’Connor, Peter B.

    2008-01-01

    Isotope variability due to natural processes provides important information for studying a variety of complex natural phenomena from the origins of a particular sample to the traces of biochemical reaction mechanisms. These measurements require high-precision determination of isotope ratios of a particular element involved. Isotope Ratio Mass Spectrometers (IRMS) are widely employed tools for such a high-precision analysis, which have some limitations. This work aims at overcoming the limitations inherent to IRMS by estimating the elemental isotopic abundance from the experimental isotopic distribution. In particular, a computational method has been derived which allows the calculation of 13C/12C ratios from the whole isotopic distributions, given certain caveats, and these calculations are applied to several cases to demonstrate their utility. The limitations of the method in terms of the required number of ions and S/N ratio are discussed. For high-precision estimates of the isotope ratios, this method requires very precise measurement of the experimental isotopic distribution abundances, free from any artifacts introduced by noise, sample heterogeneity, or other experimental sources. PMID:17263354

  15. Hydrogen peroxide route to Sn-doped titania photocatalysts

    PubMed Central

    2012-01-01

    Background The work aims at improving photocatalytic activity of titania under Vis light irradiation using modification by Sn ions and an original, simple synthesis method. Tin-doped titania catalysts were prepared by thermal hydrolysis of aqueous solutions of titanium peroxo-complexes in the presence of SnCl4 or SnCl2 using an original, proprietary "one pot" synthesis not employing organic solvents, metallo-organic precursors, autoclave aging nor post-synthesis calcination. The products were characterized in details by powder diffraction, XPS, UV–vis, IR, and Raman spectroscopies, electron microscopy and surface area and porosity measurements Results The presence of tin in synthesis mixtures favors the formation of rutile and brookite at the expense of anatase, decreases the particle size of all formed titania polymorphs, and extends light absorption of titania to visible light region >400 nm by both red shift of the absorption edge and introduction of new chromophores. The photocatalytic activity of titania under UV irradiation and >400 nm light was tested by decomposition kinetics of Orange II dye in aqueous solution Conclusions Doping by Sn improves titania photoactivity under UV light and affords considerable photoactivity under >400 nm light due to increased specific surface area and a phase heterogeneity of the Sn-doped titania powders. PMID:23035821

  16. SN 2004aw: confirming diversity of Type Ic supernovae

    NASA Astrophysics Data System (ADS)

    Taubenberger, S.; Pastorello, A.; Mazzali, P. A.; Valenti, S.; Pignata, G.; Sauer, D. N.; Arbey, A.; Bärnbantner, O.; Benetti, S.; Della Valle, A.; Deng, J.; Elias-Rosa, N.; Filippenko, A. V.; Foley, R. J.; Goobar, A.; Kotak, R.; Li, W.; Meikle, P.; Mendez, J.; Patat, F.; Pian, E.; Ries, C.; Ruiz-Lapuente, P.; Salvo, M.; Stanishev, V.; Turatto, M.; Hillebrandt, W.

    2006-09-01

    Optical and near-infrared (near-IR) observations of the Type Ic supernova (SN Ic) 2004aw are presented, obtained from -3 to +413 d with respect to the B-band maximum. The photometric evolution is characterized by a comparatively slow post-maximum decline of the light curves. The peaks in redder bands are significantly delayed relative to the bluer bands, the I-band maximum occurring 8.4 d later than that in B. With an absolute peak magnitude of -18.02 in the V band the SN can be considered fairly bright, but not exceptional. This also holds for the U through I bolometric light curve, where SN 2004aw has a position intermediate between SNe 2002ap and 1998bw. Spectroscopically SN 2004aw provides a link between a normal SN Ic like SN 1994I and the group of broad-lined SNe Ic. The spectral evolution is rather slow, with a spectrum at day +64 being still predominantly photospheric. The shape of the nebular [OI] λλ6300, 6364 line indicates a highly aspherical explosion. Helium cannot be unambiguously identified in the spectra, even in the near-IR. Using an analytical description of the light-curve peak we find that the total mass of the ejecta in SN 2004aw is 3.5-8.0Msolar, significantly larger than that in SN 1994I, although not as large as in SN 1998bw. The same model suggests that about 0.3Msolar of 56Ni has been synthesized in the explosion. No connection to a GRB can be firmly established. Based on observations at ESO-Paranal, Prog. 074.D-0161(A). E-mail: tauben@mpa-garching.mpg.de

  17. Isotopic Biogeochemistry

    NASA Technical Reports Server (NTRS)

    Hayes, J. M.

    1985-01-01

    An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

  18. Mass-independent isotopic fractionation of tin in a chemical exchange reaction

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Moynier, F.

    2008-12-01

    Tin isotopes were fractionated by the liquid-liquid extraction technique with a crown ether, dicyclohexano-18- crown-6 (DC18C6). Tin dichloride was dissolved in HCl to create solutions, 0.1 mol dm-3 (M) Sn(II) in various [HCl]. The organic phase was 0.1 M DC18C6 in 1,2-dichloroethane. A 5 cm3 aqueous solution and a 5 cm3 organic solution were mixed in a glass vial with a stirrer bar, and the glass vial was sealed. The two phases were stirred by a magnetic stirrer, and after the equilibrium, the two phases were separated by centrifugation. An aliquot of the upper aqueous solution was taken for analysis. These procedures were carried out at room temperature. The Sn concentration in the equilibrated aqueous phase was analyzed by ICP-AES. In order to avoid any matrix effect, possible trace of organic materials from DC18C6 was separated from the Sn on a micro-column anion-exchange resin in HBr/HNO3. An aliquot of the aqueous phase was once dried by heating and then dissolved into a HBr solution. Sn was strongly adsorbed while organic materials went through. Finally Sn was collected in a HNO3 solution. A solution containing 300 ppb of Sn in 0.05 M HNO3 was prepared for isotopic analysis. Isotopic ratios of Sn in all samples were analyzed with the MC-ICP-MS Nu plasma 500 HR at ENS Lyon coupled with a desolvating nebulizer Nu DSN-100 (with a typical precision of <100 ppm). The instrumental mass bias was controlled by bracketing each of the samples with standards. Because 120Sn is the most abundant isotopes, the isotope ratios have been measured as mSn/120Sn (m : 116, 117, 118, 119, 122, and 124). 114Sn and 115Sn were not analyzed due to their low abundances. Possible interferences with Cd on the masses 116, with Te on the mass 120, 122 and 124 were verified to be under the detection of the ICP-MS. Odd atomic mass isotopes (117Sn and 119Sn) showed deficits of enrichment comparing to the even atomic mass isotopes (116Sn, 118Sn, 122Sn, and 124Sn). This odd-even staggering

  19. Synthesis and photocatalytic study of SnO2/Zn2SnO4 nanocomposite prepared by sol-gel method using single source molecular precursor

    NASA Astrophysics Data System (ADS)

    Ullah, Hameed; Khatoon, Asma; Akhtar, Zareen

    2014-12-01

    A single-source molecular precursor (SSP), ([Cl2Sn(μ-OtBu)2ZnCl2(bpy)]), was designed, developed, and subsequently used in a sol-gel process for the synthesis of SnO2/Zn2SnO4 nanocomposite at pH 9 adjusted by using a NaOH solution. The pre- and post-sintering IR spectra revealed the presence and absence, respectively, of the OH group. The powder XRD confirms the formation of the single crystalline ZnSn(OH)6 phase before sintering. However, the sintered product is composed of coupled oxides, i.e. the binary SnO2 and ternary Zn2SnO4. The scanning electron microscope (SEM) images taken after sonicating the SnO2/Zn2SnO4 powder show the macroporous texture of the powder. The uniformly sized particles are in two different morphological forms, i.e. cubic and spherical. The energy-dispersive x-ray (EDX) spectroscopy confirms the elemental composition of the SnO2/Zn2SnO4 nanocomposite (Zn:Sn:O = 2:2:6). The photocatalytic efficiency of the SnO2/Zn2SnO4 nanocomposite was tested by using the dye Sudan Red B a colorant used in red chilies. More than 82% of the dye degraded after 120 min of exposure to the UV light. The efficient photocatalytic activity is attributed to the better electron/hole pair separation which resulted from the coupling of Zn2SnO4 and SnO2 at the molecular level and produced efficient grain boundary interfaces.

  20. Measurement of the Abundance of Radioactive Be-10 and Other Light Isotopes in Cosmic Radiation Up to 2 GeV /Nucleon with the Balloon-Borne Instrument Isomax

    NASA Technical Reports Server (NTRS)

    Hams, T.; Barbier, L. M.; Bremerich, M.; Christian, E. R.; deNolfo, G. A.; Geier, S.; Goebel, H.; Gupta, S. K.; Hof, M.; Menn, W.

    2004-01-01

    The Isotope Magnet Experiment (ISOMAX), a balloon-borne superconducting magnet spectrometer, was designed to measure the isotopic composition of the light isotopes (3 les than or = Z less than or = 8) of cosmic radiation up to 4 GeV/nucleon with a mass resolution of better than 0.25 amu by using the velocity versus rigidity technique. To achieve this stringent mass resolution, ISOMAX was composed of three major detector systems: a magnetic rigidity spectrometer with a precision drift chamber tracker in conjunction with a three-layer time-of-flight system, and two silica-aerogel Cerenkov counters for velocity determination. A special emphasis of the ISOMAX program was the accurate measurement of radioactive Be-10 with respect to its stable neighbor isotope Be-9, which provides important constraints on the age of cosmic rays in the Galaxy. ISOMAX had its first balloon flight on 1998 August 4-5 from Lynn Lake, Manitoba, Canada. Thirteen hours of data were recorded during this flight at a residual atmosphere of less than 5 g/sq cm. The isotopic ratio at the top of the atmosphere for Be-10/Be-9 was measured to be 0.195 +/- 0.036 (statistical) +/- 0.039 (systematic) between 0.26 and 1.03 GeV/nucleon and 0.317 +/- 0.109(statistical) +/- 0.042(systematic) between 1.13 and 2.03 GeV/nucleon. This is the first measurement of its kind above l GeV/nucleon. ISOMAX results tend to be higher than predictions from current propagation models. In addition to the beryllium results, we report the isotopic ratios of neighboring lithium and boron in the energy range of the time-of-flight system (up to approx. 1 GeV/nucleon). The lithium and boron ratios agree well with existing data and model predictions at similar energies.

  1. Simulating the Outer Nebula of SN 1987A

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, Ben; Morris, Thomas; Podsiadlowski, Philipp

    2014-01-01

    As has been shown previously, the triple-ring nebula around SN 1987A can be understood as a direct consequence of the merger of two stars, some 20,000 yr before the explosion. Here we present new SPH simulations that also include the pre-merger mass loss and show that this may be able to explain other structures observed around SN 1987A, such as Napoleon's hat and various light echoes.

  2. Method for isotope separation by photodeflection

    DOEpatents

    Bernhardt, Anthony F.

    1977-01-01

    In the method of separating isotopes wherein a desired isotope species is selectively deflected out of a beam of mixed isotopes by irradiating the beam with a directed beam of light of narrowly defined frequency which is selectively absorbed by the desired species, the improvement comprising irradiating the deflected beam with light from other light sources whose frequencies are selected to cause the depopulation of any metastable excited states.

  3. Precisely Controlled Synthesis of High Quality Kesterite Cu2ZnSnS4 Thin Film via Co-Electrodeposited CuZnSn Alloy Film.

    PubMed

    Hreid, Tubshin; Tiong, Vincent Tiing; Cai, Molang; Wang, Hongxia; Will, Geoffrey

    2016-06-01

    In this work, a facile co-electrodeposition method was used to fabricate CuZnSn alloy films where the content of copper, zinc and tin could be precisely controlled through manipulating the mass transfer process in the electrochemical deposition. By finely tuning the concentration of the cations of Cu2+, Zn2+ and Sn2+ in the electrochemical bath solution, uniform CuZnSn film with desired composition of copper poor and zinc rich was made. Sulphurisation of the CuZnSn alloy film led to the formation of compact and large grains Cu2ZnSnS4 thin film absorber with an optimum composition of Cu/(Zn+Sn) ≈ 0.8, Zn/Sn ≈ 1.2. Both SEM morphology and EDS mapping results confirmed the uniformity of the CuZnSn and Cu2ZnSnS4 films and the homogeneous distribution of Cu, Zn, Sn and S elements in the bulk films. The XRD and Raman measurements indicated that the synthesized Cu2ZnSnS4 film was kesterite phase without impurities detected. Photoelectrochemical tests were carried out to evaluate the CZTS film's photocurrent response under illumination of green light. PMID:27427618

  4. Isotope separation by laser means

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

    1982-06-15

    A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

  5. Calculation of the Transition from Pairing Vibrational to Pairing Rotational Regimes between Magic Nuclei {sup 100}Sn and {sup 132}Sn via Two-Nucleon Transfer Reactions

    SciTech Connect

    Potel, G.; Barranco, F.; Marini, F.; Idini, A.; Vigezzi, E.; Broglia, R. A.

    2011-08-26

    Absolute values of two-particle transfer cross sections along the Sn-isotopic chain are calculated. They agree with measurements within errors and without free parameters. Within this scenario, the predictions concerning the absolute value of the two-particle transfer cross sections associated with the excitation of the pairing vibrational spectrum expected around the recently discovered closed shell nucleus {sub 50}{sup 132}Sn{sub 82} and the very exotic nucleus {sub 50}{sup 100}Sn{sub 50} can be considered quantitative, opening new perspectives in the study of pairing in nuclei.

  6. SAINTS - The SN 1987A Intensive Study

    NASA Astrophysics Data System (ADS)

    Kirshner, Robert

    2010-09-01

    SAINTS is a program to observe SN 1987A, the brightest supernova since 1604, as it matures into the youngest supernova remnant at age 23. HST is the essential tool for observing SN 1987A's many physical components. A violent encounter is underway between the fastest-moving debris and the circumstellar ring: shocks excite "hotspots." Radio, optical, infrared and X-ray fluxes have been rising rapidly: we have organized VLT, Spitzer, and Chandra observations to understand the several emission mechanisms at work. The inner debris, excited by radioactive isotopes from the explosion, is now resolved and seen to be aspherical, providing direct evidence on the shape of the explosion itself and on dust that formed in the debris. Questions about SN 1987A remain unanswered. For example, whereis the compact object whose formation sent neutrinos our way in February 1987 ? A rich and unbroken data set from SAINTS will help answer these central questions and will build an archive for the future to help answer questions we have not yet thought to ask. For Cycle 18, these data will include novel observations with the IR channel of WFC3 and UV observations with COS.

  7. The Peculiar SN 2005hk: Do Some Type Ia Supernovae Explode As Deflagrations?

    SciTech Connect

    Phillips, M.M.; Li, W.; Frieman, J.A.; Blinnikov, S.I.; DePoy, D.; Prieto, J.L.; Milne, P.; Contreras, C.; Folatelli, Gaston; Morrell, N.; Hamuy, M.; Suntzeff, N.B.; Roth, M.; Gonzalez, S.; Krzeminski, W.; Filippenko, A.V.; Freedman, W.L.; Chornock, R.; Jha, S.; Madore, B.F.; Persson, S.E.; /Las Campanas Observ. /UC, Berkeley, Astron. Dept. /Chicago U., Astron. Astrophys. Ctr. /KICP, Chicago /Fermilab /Moscow, ITEP /Garching, Max Planck Inst. /Ohio State U., Dept. Astron. /Arizona U., Astron. Dept. - Steward Observ. /Chile U., Santiago /Texas A-M /Carnegie Inst. Observ. /KIPAC, Menlo Park /Caltech, IPAC /Notre Dame U. /South African Astron. Observ. /Cape Town U. /Washington U., Seattle, Astron. Dept. /New Mexico State U. /Chicago U., FLASH /Baltimore, Space Telescope Sci.

    2006-11-14

    We present extensive u{prime}g{prime}r{prime}i{prime} BV RIY JHK{sub s} photometry and optical spectroscopy of SN 2005hk. These data reveal that SN 2005hk was nearly identical in its observed properties to SN 2002cx, which has been called 'the most peculiar known type Ia supernova'. Both supernovae exhibited high ionization SN 1991T-like pre-maximum spectra, yet low peak luminosities like SN 1991bg. The spectra reveal that SN 2005hk, like SN 2002cx, exhibited expansion velocities that were roughly half those of typical type Ia supernovae. The R and I light curves of both supernovae were also peculiar in not displaying the secondary maximum observed for normal type Ia supernovae. Our Y JH photometry of SN 2005hk reveals the same peculiarity in the near-infrared. By combining our optical and near-infrared photometry of SN 2005hk with published ultraviolet light curves obtained with the Swift satellite, we are able to construct a bolometric light curve from {approx} 10 days before to {approx}60 days after B maximum. The shape and unusually low peak luminosity of this light curve, plus the low expansion velocities and absence of a secondary maximum at red and near-infrared wavelengths, are all in reasonable agreement with model calculations of a 3D deflagration which produces {approx} 0.25 M{sub {circle_dot}} of {sup 56}Ni.

  8. Combination of the (87)Sr/(86)Sr ratio and light stable isotopic values (δ(13)C, δ(15)N and δD) for identifying the geographical origin of winter wheat in China.

    PubMed

    Liu, Hongyan; Wei, Yimin; Lu, Hai; Wei, Shuai; Jiang, Tao; Zhang, Yingquan; Guo, Boli

    2016-12-01

    This study aims to investigate whether isotopic signatures can be used to develop reliable fingerprints for discriminating the geographical origin of Chinese winter wheat, and to evaluate the discrimination effects of δ(13)C, δ(15)N and δD, alone or with (87)Sr/(86)Sr. In this study, the values of δ(13)C, δ(15)N and δD, and the (87)Sr/(86)Sr ratios of wheat and provenance soils from three regions were determined. Significant differences were found in all parameters of wheat and (87)Sr/(86)Sr in soil extract (reflecting the bioavailable fraction of soil) among different regions. A significantly positive correlation was observed between the (87)Sr/(86)Sr ratios of wheat and soil extracts. An overall correct classification rate of 77.8% was obtained for discriminating wheat from three regions based on light stable isotopes (δ(13)C, δ(15)N, and δD). The correct classification rate of 98.1% could be obtained with the combination of the (87)Sr/(86)Sr ratio and the light stable isotopic values.

  9. Preparation and Characterization of SnO2/Ag Hollow Microsphere via a Convenient Hydrothermal Route.

    PubMed

    Qiao, Xiuqing; Hu, Fuchao; Hou, Dongfang; Li, Dongsheng

    2016-04-01

    SnO2/Ag hollow microsphere, assembled form SnO2 and Ag nanoparticles, was synthesized via a facile one-step hydrothermal synthesis method using Na2SnO3.3H2O, CO(NH2)2 and AgNO3 as raw materials. XRD, SEM, and TEM results revealed that the obtained SnO2/Ag hollow microsphere with diameters of ca.3-5 µm was built from uniformly distributed rutile SnO2 and cubic Ag nanoparticles. Moreover, XPS results indicate the existence of strong interaction between Ag and SnO2 nanoparticles, rather than simply physical contact, endowing the SnO2/Ag hollow microspheres with excellent photocatalytic performance in the degradation of RhB solution under visible light irradiation. PMID:27451773

  10. SN1987A's Twentieth Anniversary

    NASA Astrophysics Data System (ADS)

    2007-02-01

    Looking back at 20 Years of Observations of this Supernova with ESO telescopes The unique supernova SN 1987A has been a bonanza for astrophysicists. It provided several observational 'firsts,' like the detection of neutrinos from an exploding star, the observation of the progenitor star on archival photographic plates, the signatures of a non-spherical explosion, the direct observation of the radioactive elements produced during the blast, observation of the formation of dust in the supernova, as well as the detection of circumstellar and interstellar material. ESO PR Photo 08a/07 ESO PR Photo 08a/07 SN1987A in the Large Magellanic Cloud Today, it is exactly twenty years since the explosion of Supernova 1987A in the Large Magellanic Cloud was first observed, at a distance of 163,000 light-years. It was the first naked-eye supernova to be seen for 383 years. Few events in modern astronomy have met with such an enthusiastic response by the scientists and now, after 20 years, it continues to be an extremely exciting object that is further studied by astronomers around the world, in particular using ESO's telescopes. When the first signs of Supernova 1987A, the first supernova of the year 1987, were noticed early on 24 February of that year, it was clear that this would be an unusual event. It was discovered by naked-eye and on a panoramic photographic plate taken with a 10-inch astrograph on Las Campanas in Chile by Oscar Duhalde and Ian Shelton, respectively. A few hours earlier, still on 23 February, two large underground detectors - in Japan and the USA - had registered the passage of high-energy neutrinos. Since SN 1987A exploded in the Large Magellanic Cloud (LMC), it was only accessible to telescopes in the Southern Hemisphere, more particularly in Australia, South Africa, and South America. In Chile, ESO's observatory at La Silla with its armada of telescopes with sizes between 0.5 and 3.6-m, played an important role. ESO PR Photo 08c/07 ESO PR Photo 08c/07 The

  11. SN 2008ha: AN EXTREMELY LOW LUMINOSITY AND EXCEPTIONALLY LOW ENERGY SUPERNOVA

    SciTech Connect

    Foley, Ryan J.; Kirshner, Robert P.; Challis, Peter J.; Friedman, Andrew S.; Chornock, Ryan; Filippenko, Alexei V.; Ganeshalingam, Mohan; Li, Weidong; Cenko, S. Bradley; Modjaz, Maryam; Silverman, Jeffrey M.; Wood-Vasey, W. Michael

    2009-08-15

    We present ultraviolet, optical, and near-infrared photometry as well as optical spectra of the peculiar supernova (SN) 2008ha. SN 2008ha had a very low peak luminosity, reaching only M{sub V} = -14.2 mag, and low line velocities of only {approx}2000 km s{sup -1} near maximum brightness, indicating a very small kinetic energy per unit mass of ejecta. Spectroscopically, SN 2008ha is a member of the SN 2002cx-like class of SNe, a peculiar subclass of SNe Ia; however, SN 2008ha is the most extreme member, being significantly fainter and having lower line velocities than the typical member, which is already {approx}2 mag fainter and has line velocities {approx}5000 km s{sup -1} smaller (near maximum brightness) than a normal SN Ia. SN 2008ha had a remarkably short rise time of only {approx}10 days, significantly shorter than either SN 2002cx-like objects ({approx}15 days) or normal SNe Ia ({approx}19.5 days). The bolometric light curve of SN 2008ha indicates that SN 2008ha peaked at L {sub peak} = (9.5 {+-} 1.4) x 10{sup 40} erg s{sup -1}, making SN 2008ha perhaps the least luminous SN ever observed. From its peak luminosity and rise time, we infer that SN 2008ha generated (3.0 {+-} 0.9) x 10{sup -3} M {sub sun} of {sup 56}Ni, had a kinetic energy of {approx}2 x 10{sup 48} erg, and ejected 0.15 M {sub sun} of material. The host galaxy of SN 2008ha has a luminosity, star formation rate, and metallicity similar to those of the Large magellanic Cloud. We classify three new (and one potential) members of the SN 2002cx-like class, expanding the sample to 14 (and one potential) members. The host-galaxy morphology distribution of the class is consistent with that of SNe Ia, Ib, Ic, and II. Several models for generating low-luminosity SNe can explain the observations of SN 2008ha; however, if a single model is to describe all SN 2002cx-like objects, deflagration of carbon-oxygen white dwarfs, with SN 2008ha being a partial deflagration and not unbinding the progenitor star, is

  12. Resolving the stellar sources of isotopically rare presolar silicate grains through Mg and Fe isotopic analyses

    SciTech Connect

    Nguyen, Ann N.; Messenger, Scott

    2014-04-01

    We conducted multi-element isotopic analyses of 11 presolar silicate grains from the Acfer 094 meteorite having unusual O isotopic compositions. Eight grains are {sup 18}O-rich, one is {sup 16}O-rich, and two are extremely {sup 17}O-rich. We constrained the grains' stellar sources by measuring their Si and Mg isotopic ratios, and also the {sup 54}Fe/{sup 56}Fe and {sup 57}Fe/{sup 56}Fe ratios for five grains. The Mg and Fe isotopic measurements were conducted after surrounding matrix grains were removed for more accurate ratios. Most of the {sup 18}O-rich silicates had anomalous Mg isotopic ratios, and their combined isotopic constraints are consistent with origins in low-mass Type II supernovae (SNe II) rather than high-metallicity stars. The isotopic ratios of the {sup 16}O-rich silicate are also consistent with an SN origin. Mixing small amounts of interior stellar material with the stellar envelope replicated all measured isotopic ratios except for {sup 29}Si/{sup 28}Si and {sup 54}Fe/{sup 56}Fe in some grains. The {sup 29}Si/{sup 28}Si ratios of all SN-derived grains are matched by doubling the {sup 29}Si yield in the Ne- and Si-burning zones. The {sup 54}Fe/{sup 56}Fe ratios of the grains imply elemental fractionation in the Si/S zone, or introduction of isotopically solar Fe by secondary processing. The two highly {sup 17}O-rich silicates exhibited significant {sup 25}Mg and/or {sup 26}Mg enrichments and their isotopic ratios are best explained by strong dilution of 1.15 M {sub ☉} CO nova matter. We estimate that ∼12% and 1% of presolar silicates have SN and nova origins, respectively, similar to presolar SiC and oxides. This implies that asymptotic giant branch stars are the dominant dust producers in the galaxy.

  13. Developing a Clinically Useful Calcium Isotope Biomarker

    NASA Technical Reports Server (NTRS)

    Romaniello, Stephen J.; Anbar, Ariel D.; Gordon, Gwyneth W.; Skulan, Joseph L.; Smith, Scott M.; Zwart, Sara R.; Monge, Jorge; Fonseca, Rafael

    2016-01-01

    Naturally-occurring Ca is mixture of six isotopes Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48). Biological reaction rates and equilibrium constants depend slightly, but measurably, on atomic mass, causing the relative abundances of Ca isotopes to vary between different tissues. During bone formation, light isotopes of Ca are preferentially incorporated into bone, leaving soft tissue depleted in light isotopes. In contrast, bone resorption exhibits no isotopic preference, and thus transfers the light isotope signature of bone back to soft tissue. This balance makes the Ca isotope composition of soft tissue (e.g. serum, urine) a highly sensitive, quantitative tracer for whole-body bone mineral balance (BMB).

  14. Isotopic fractionation by diffusion in groundwater

    NASA Astrophysics Data System (ADS)

    Labolle, Eric M.; Fogg, Graham E.; Eweis, Juana B.; Gravner, Janko; Leaist, Derek G.

    2008-07-01

    During the last decade, isotopic fractionation has gained acceptance as an indicator of microbiological and chemical transformations of contaminants in groundwater. These transformation processes typically favor isotopically light, compared to isotopically heavy, contaminants, resulting in enrichment of the latter in the residual aqueous phase. In these isotope applications, it has been generally presumed that physical transport processes in groundwater have a negligible effect on isotopic enrichment. It is well known, however, that aqueous phase diffusion generally proceeds faster for isotopically light, compared to isotopically heavy, solute molecules, often resulting in isotopic fractionation in groundwater. This paper considers the potential for isotopic fractionation during transport in groundwater resulting from minute isotopic effects on aqueous diffusion coefficients. Analyses of transport in heterogeneous systems delimit the viable range of isotopic fractionation by diffusion in groundwater. Results show that diffusion can result in similar degrees of depletion and enrichment of isotopically heavy solutes during transport in heterogeneous systems with significant diffusion rate-limited mass transfer between fast- and slow-flow zones. Additional analyses and examples explore conditions that attenuate the development of significant fractionation. Examples are presented for 13C methyl tertiary butyl ether and deuterated and nondeuterated isopropanol and tertiary butyl alcohol using aqueous diffusion coefficients measured by the Taylor dispersion method with refractive index profiling as a part of this study. Examples elucidate the potential for diffusive fractionation as a confounder in isotope applications and emphasize the importance of hydrogeologic analysis for assessing the role of diffusive fractionation in isotope applications at contaminant field sites.

  15. SnET2: clinical update

    NASA Astrophysics Data System (ADS)

    Razum, Nicholas J.; Snyder, Albert B.; Doiron, Daniel R.

    1996-04-01

    Tin Ethyl Etiopurpurin, SnET2, is a synthetic chlorin analog presently in Phase-II/III clinical trials for the treatment of cutaneous cancers. Trials to date include the treatment of basal cell carcinomas, squamous cell carcinomas, breast adenocarcinomas metastatic to the chest wall and cutaneous Kaposi's sarcomas in AIDS patients. Results to date have shown significant clinical responses for drug doses between 1.0 mg/kg and 1.6 mg/kg, with the threshold for Kaposi's sarcoma being slightly higher than in other indications. Light doses from 100 J/cm2 to 300 J/cm2 were delivered from 24 to 72 hours post SnET2 infusion. Induced transient skin photosensitivity at the lower therapeutic doses has been mild, lasting approximately a week. Results of the Phase I and II trials are presented.

  16. Z = 50 core stability in 110Sn from magnetic-moment and lifetime measurements

    DOE PAGES

    Kumbartzki, G. J.; Benczer-Koller, N.; Speidel, K. -H.; Torres, D. A.; Allmond, James M.; Fallon, P.; Abramovic, I.; L. A. Bernstein; Bevins, J. E.; Crawford, H. L.; et al

    2016-04-18

    In this study, the structure of the semimagic Sn50 isotopes were previously studied via measurements of B(E2;21+ → 01+) and g factors of 21+ states. The values of the B(E2;21+) in the isotopes below midshell at N = 66 show an enhancement in collectivity, contrary to predictions from shell-model calculations. This work presents the first measurement of the 21+ and 41+ states' magnetic moments in the unstable neutron-deficient 110Sn. The g factors provide complementary structure information to the interpretation of the observed B(E2) values.

  17. Hubble Residuals of Nearby SN Ia Are Correlated with Host Galaxy Masses

    SciTech Connect

    Kelly, Patrick L.; Hicken, Malcolm; Burke, David L.; Mandel, Kaisey S.; Kirshner, Robert P.; /Harvard-Smithsonian Ctr. Astrophys.

    2010-05-03

    From Sloan Digital Sky Survey u{prime} g{prime} r{prime} i{prime} z{prime} imaging, we estimate the stellar masses of the host galaxies of 70 low redshift SN Ia (0.015 < z < 0.08) from the hosts absolute luminosities and mass-to-light ratios. These nearby SN were discovered largely by searches targeting luminous galaxies, and we find that their host galaxies are substantially more massive than the hosts of SN discovered by the flux-limited Supernova Legacy Survey. Testing four separate light curve fitters, we detect {approx}2.5{sigma} correlations of Hubble residuals with both host galaxy size and stellar mass, such that SN Ia occurring in physically larger, more massive hosts are {approx}10% brighter after light curve correction. The Hubble residual is the deviation of the inferred distance modulus to the SN, calculated from its apparent luminosity and light curve properties, away from the expected value at the SN redshift. Marginalizing over linear trends in Hubble residuals with light curve parameters shows that the correlations cannot be attributed to a light curve-dependent calibration error. Combining 180 higher-redshift ESSENCE, SNLS, and HigherZ SN with 30 nearby SN whose host masses are less than 10{sup 10.8} M{circle_dot} n a cosmology fit yields 1 + w = 0.22{sub -0.108}{sup +0.152}, while a combination where the 30 nearby SN instead have host masses greater than 10{sup 10.8} M{circle_dot} yields 1 + w = ?0.03{sub -0.143}{sup +0.217}. Progenitor metallicity, stellar population age, and dust extinction correlate with galaxy mass and may be responsible for these systematic effects. Host galaxy measurements will yield improved distances to SN Ia.

  18. Isospin transport in 84Kr+112,124Sn reactions at Fermi energies

    NASA Astrophysics Data System (ADS)

    Piantelli, S.; Casini, G.; Olmi, A.; Barlini, S.; Bini, M.; Carboni, S.; Maurenzig, P. R.; Pasquali, G.; Poggi, G.; Stefanini, A. A.; Bougault, R.; Le Neindre, N.; Lopez, O.; Parlog, M.; Vient, E.; Bonnet, E.; Chbihi, A.; Frankland, J. D.; Gruyer, D.; Rosato, E.; Spadaccini, G.; Vigilante, M.; Borderie, B.; Rivet, M. F.; Bruno, M.; Morelli, L.; Cinausero, M.; Degerlier, M.; Gramegna, F.; Marchi, T.; Alba, R.; Maiolino, C.; Santonocito, D.; Kozik, T.; Twarog, T.

    2014-03-01

    Isospin transport phenomena in dissipative heavy ion collisions have been investigated at Fermi energies with a beam of 84Kr at 35AMeV. A comparison of the /Z of light and medium products forward-emitted in the centre of mass frame when the beam impinges on two different targets, the n-poor 112Sn and the n-rich 124Sn, is presented. Data were collected by means of a three-layer telescope with very good performances in terms of mass identification (full isotopic resolution up to Z ~ 20 for ions punching through the first detector layer) built by the FAZIA Collaboration and located just beyond the grazing angle for both reactions. The /Z of the products detected when the n-rich target is used is always higher than that associated to the n-poor one; since the detector was able to measure only fragments coming from the QuasiProjectile decay and/or neck emission, the observed behaviour can be ascribed to the isospin diffusion process, driven by the isospin gradient between QuasiProjectile and QuasiTarget. Moreover, for light fragments the /Z as a function of the lab velocity of the fragment is observed to increase when we move from the QuasiProjectile velocity to the centre of mass (neck zone). This effect can be interpreted as an evidence of isospin drift driven by the density gradient between the QuasiProjectile zone (at normal density) and the more diluted neck zone.

  19. THE LONG-LIVED UV ''PLATEAU'' OF SN 2012aw

    SciTech Connect

    Bayless, Amanda J.; Roming, Peter W. A.; Pritchard, Tyler A.; Kuin, Paul; Brown, Peter J.; Botticella, Maria Teresa; Dall'Ora, Massimo; Frey, Lucille H.; Even, Wesley; Fryer, Chris L.; Maund, Justyn R.; Fraser, Morgan

    2013-02-10

    Observations with the Swift UV Optical Telescope have unambiguously uncovered for the first time a long-lived, UV ''plateau'' in a Type II-P supernova (SN). Although this flattening in slope is hinted at in a few other SNe, due to its proximity and minimal line-of-sight extinction, SN 2012aw has afforded the first opportunity to clearly observe this UV plateau. The observations of SN 2012aw revealed all Swift UV and u-band light curves initially declined rapidly, but 27 days after the explosion the light curves flattened. Some possible sources of the UV plateau are the same thermal process that causes the optical plateau, heating from radioactive decay, or a combination of both processes.

  20. Native Sn-Pb droplets in a zeolitic amygdale (Isle of Mull, Inner Hebrides)

    NASA Astrophysics Data System (ADS)

    Dekov, Vesselin M.; Hålenius, Ulf; Billström, Kjell; Kamenov, George D.; Munnik, Frans; Eriksson, Lars; Dyer, Alan; Schmidt, Mark; Botz, Reiner

    2009-05-01

    Despite the particular scientific interest in the elements with high affinity to S and O 2, but found in zero-valence state in nature, the origin of these native minerals has been little explored and remains obscure. Here we describe unique Sn-Pb droplets found in a closed analcime-calcite amygdale collected from a basaltic unit cropping out at Carsaig Bay (Isle of Mull, Inner Hebrides). The droplets consist of intimate intergrowths of nearly pure Sn 0 and Pb 0 domains in proportion 88:12 and are enveloped in a thin, brownish film of organic composition. The occurrence of the Sn-Pb droplets in a closed amygdale, their relationship with the host analcime + calcite and their Pb isotope composition (which does not match any known anthropogenic Pb source) rule out the possibility of anthropogenic contamination and support the natural origin of the Sn-Pb alloy. The variable isotope (Pb, Sr, Nd) compositions in different members of the host basaltic sequence suggest that a parent basaltic magma was modified by crustal assimilation and post-emplacement alteration processes. Considering all possible explanations, it appears that the most likely source of Pb for the Sn-Pb alloy is a discrete basaltic unit with an isotopic composition comparable to the Antrim basalts (Northern Ireland). The amygdale phases, on the other hand, show isotopic evidence for incorporation of elements from both local basaltic and sedimentary units. The apparent isotopic disequilibrium between Sn-Pb droplets and amygdale phases indicates a complex, multi-stage fluid evolution. The occurrence of Sn-Pb droplets in organic capsules suggests that the droplets and the enveloping organic substances are co-precipitates. This implies that the transportation and deposition of Sn and Pb might have occurred through organometallic compounds. We assume interaction of seawater fluids carrying metals leached from basaltic rocks with hydrocarbons from sedimentary units as a prerequisite for the formation of the

  1. Fabrication of cubic Zn2SnO4/SnO2 complex hollow structures and their sunlight-driven photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Sun, Linqiang; Han, Xiao; Jiang, Zhe; Ye, Tingting; Li, Rong; Zhao, Xinsheng; Han, Xiguang

    2016-06-01

    Uniform hollow, yolk-shell and double-shell Zn2SnO4/SnO2 nanoparticles with cubic morphologies have been synthesized using ``etching-second growth-annealed'' methods. Due to the high light-harvesting efficiency and low recombination rate of the photo-generated electron-hole pair, double-shell structures of Zn2SnO4/SnO2 nanoparticles show an obvious improvement in photocatalytic activity.Uniform hollow, yolk-shell and double-shell Zn2SnO4/SnO2 nanoparticles with cubic morphologies have been synthesized using ``etching-second growth-annealed'' methods. Due to the high light-harvesting efficiency and low recombination rate of the photo-generated electron-hole pair, double-shell structures of Zn2SnO4/SnO2 nanoparticles show an obvious improvement in photocatalytic activity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08004e

  2. Isotope separation

    DOEpatents

    Bartlett, Rodney J.; Morrey, John R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  3. Photocatalytic performance of Ag doped SnO2 nanoparticles modified with curcumin

    NASA Astrophysics Data System (ADS)

    Vignesh, K.; Hariharan, R.; Rajarajan, M.; Suganthi, A.

    2013-07-01

    Visible light active Ag doped SnO2 nanoparticles modified with curcumin (Cur-Ag-SnO2) have been prepared by a combined precipitation and chemical impregnation route. The optical properties, phase structures and morphologies of the as-prepared nanoparticles were characterized using UV-visible diffuse reflectance spectra (UV-vis-DRS), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The surface area was measured by Brunauer. Emmett. Teller (B.E.T) analysis. Compared to bare SnO2, the surface modified photocatalysts (Ag-SnO2 and Cur-Ag-SnO2) showed a red shift in the visible region. The photocatalytic activity was monitored via the degradation of rose bengal (RB) dye and the results revealed that Cur-Ag-SnO2 shows better photocatalytic activity than that of Ag-SnO2 and SnO2. The superior photocatalytic activity of Cur-Ag-SnO2 could be attributed to the effective electron-hole separation by surface modification. The effect of photocatalyst concentration, initial dye concentration and electron scavenger on the photocatalytic activity was examined in detail. Furthermore, the antifungal activity of the photocatalysts and the reusability of Cur-Ag-SnO2 were tested.

  4. BaCdSnS4 and Ba3CdSn2S8: syntheses, structures, and non-linear optical and photoluminescence properties.

    PubMed

    Zhen, Ni; Wu, Kui; Wang, Ying; Li, Qiang; Gao, Wenhui; Hou, Dianwei; Yang, Zhihua; Jiang, Huaidong; Dong, Yongjun; Pan, Shilie

    2016-06-28

    Two non-centrosymmetric metal chalcogenides, BaCdSnS4 and Ba3CdSn2S8, were synthesized using a high temperature solid-state reaction in an evacuated silica tube. Although the two compounds have the same building units in their structures, namely CdS4, SnS4 and BaS8 units, both of them have different structures. BaCdSnS4 crystallizes in the orthorhombic space group Fdd2 and its structure can be characterized by the two-dimensional ∞[Cd-Sn-S] layers composed of corner- and edge-sharing CdS4 and SnS4 tetrahedra with Ba atoms located between the two adjacent ∞[Cd-Sn-S] layers. Ba3CdSn2S8 crystallizes in the space group I4[combining macron]3d of the orthorhombic system and the CdS4 and SnS4 groups are connected with each other via corner-sharing to form a three-dimensional framework, which is different from the 2D ∞[Cd-Sn-S] layer structure in BaCdSnS4. The UV-vis-NIR diffuse-reflectance spectra show that the experimental band gaps are about 2.30 eV for BaCdSnS4 and 2.75 eV for Ba3CdSn2S8, respectively. IR and Raman measurement results indicate that their transparent ranges are up to 25 μm. Second-order NLO measurements show that BaCdSnS4 exhibits strong powder second-harmonic generation (SHG) intensities at 2.09 μm laser pumping that are ∼5 and 0.7 times that of AgGaS2 in the particle size 38-55 and 150-200 μm, respectively, whereas Ba3CdSn2S8 only exhibits SHG intensities of about 0.8 and 0.1 times that of AgGaS2 at the same particle sizes. The origin of the NLO response in BaCdSnS4 may originate from the macroscopic arrangement of the SnS4 and CdS4 tetrahedra. Furthermore, the photoluminescence properties of the two compounds have also been investigated and show obvious blue and green light emission. PMID:27272926

  5. VERY LATE PHOTOMETRY OF SN 2011fe

    SciTech Connect

    Kerzendorf, W. E.; Taubenberger, S.; Seitenzahl, I. R.; Ruiter, A. J.

    2014-12-01

    The Type Ia supernova SN 2011fe is one of the closest supernovae of the past decades. Due to its proximity and low dust extinction, this object provides a very rare opportunity to study the extremely late time evolution (>900 days) of thermonuclear supernovae. In this Letter, we present our photometric data of SN 2011fe taken at an unprecedented late epoch of ≈930 days with GMOS-N mounted on the Gemini North telescope (g = 23.43 ± 0.28, r = 24.14 ± 0.14, i = 23.91 ± 0.18, and z = 23.90 ± 0.17) to study the energy production and retention in the ejecta of SN 2011fe. Together with previous measurements by other groups, our result suggests that the optical supernova light curve can still be explained by the full thermalization of the decay positrons of {sup 56}Co. This is in spite of theoretical predicted effects (e.g., infrared catastrophe, positron escape, and dust) that advocate a substantial energy redistribution and/or loss via various processes that result in a more rapid dimming at these very late epochs.

  6. Very Late Photometry of SN 2011fe

    NASA Astrophysics Data System (ADS)

    Kerzendorf, W. E.; Taubenberger, S.; Seitenzahl, I. R.; Ruiter, A. J.

    2014-12-01

    The Type Ia supernova SN 2011fe is one of the closest supernovae of the past decades. Due to its proximity and low dust extinction, this object provides a very rare opportunity to study the extremely late time evolution (>900 days) of thermonuclear supernovae. In this Letter, we present our photometric data of SN 2011fe taken at an unprecedented late epoch of ≈930 days with GMOS-N mounted on the Gemini North telescope (g = 23.43 ± 0.28, r = 24.14 ± 0.14, i = 23.91 ± 0.18, and z = 23.90 ± 0.17) to study the energy production and retention in the ejecta of SN 2011fe. Together with previous measurements by other groups, our result suggests that the optical supernova light curve can still be explained by the full thermalization of the decay positrons of 56Co. This is in spite of theoretical predicted effects (e.g., infrared catastrophe, positron escape, and dust) that advocate a substantial energy redistribution and/or loss via various processes that result in a more rapid dimming at these very late epochs.

  7. SN 2010U: A LUMINOUS NOVA IN NGC 4214

    SciTech Connect

    Humphreys, Roberta M.; Helton, L. Andrew; Prieto, Jose L.; Rosenfield, Philip; Williams, Benjamin; Murphy, Jeremiah; Dalcanton, Julianne; Gilbert, Karoline; Kochanek, Christopher S.; Stanek, K. Z.; Khan, Rubab; Szczygiel, Dorota; Mogren, Karen; Fesen, Robert A.; Milisavljevic, Dan

    2010-07-20

    The luminosity, light curve, post-maximum spectrum, and lack of a progenitor on deep pre-outburst images suggest that SN 2010U was a luminous, fast nova. Its outburst magnitude is consistent with that for a fast nova using the maximum magnitude-rate of decline relationship for classical novae.

  8. BRYOCARB: A process-based model of thallose liverwort carbon isotope fractionation in response to CO 2, O 2, light and temperature

    NASA Astrophysics Data System (ADS)

    Fletcher, Benjamin J.; Brentnall, Stuart J.; Quick, W. Paul; Beerling, David J.

    2006-12-01

    Evidence from laboratory experiments indicates that fractionation against the heavy stable isotope of carbon (Δ 13C) by bryophytes (liverworts and mosses) is strongly dependent on atmospheric CO 2. This physiological response may therefore provide the basis for developing a new terrestrial CO 2 proxy [Fletcher, B.J., Beerling, D.J., Brentnall, S.J., Royer, D.L., 2005. Fossil bryophytes as recorders of ancient CO 2 levels: experimental evidence and a Cretaceous case study. Global Biogeochem. Cycles19, GB3012]. Here, we establish a theoretical basis for the proxy by developing an extended model of bryophyte carbon isotope fractionation (BRYOCARB) that integrates the biochemical theory of photosynthetic CO 2 assimilation with controls on CO 2 supply by diffusion from the atmosphere. The BRYOCARB model is evaluated against measurements of the response of liverwort photosynthesis and Δ 13C to variations in atmospheric O 2, temperature and irradiance at different CO 2 concentrations. We show that the bryophyte proxy is at least as sensitive to variations in atmosphere CO 2 as the two other leading carbon isotope-based approaches to estimating palaeo-CO 2 levels ( δ13C of phytoplankton and of paleosols). Mathematical inversion of BRYOCARB provides a mechanistic means of estimating atmospheric CO 2 levels from fossil bryophyte carbon that can explicitly account for the effects of past differences in O 2 and climate.

  9. Standardization of Sn-113.

    PubMed

    Roteta, Miguel; Peyres, Virginia; García-Toraño, Eduardo

    2014-05-01

    The radionuclide (113)Sn is a quasi-monoenergetic gamma emitter often used in the efficiency calibration of gamma spectrometers in the energy region around 390keV. This paper presents the results of the standardization of this radionuclide by three methods: integral (4π-γ) counting with a well-type NaI(Tl) detector, liquid scintillation counting applying the CIEMAT-NIST method and 4π coincidence counting (conversion electron-X) with a digital coincidence system. PMID:24365465

  10. Mass Loss and Pre-SN Evolution of Massive Stars

    NASA Astrophysics Data System (ADS)

    Smith, N.

    2010-06-01

    I review the role that mass loss plays in the pre-SN evolution of massive stars in a variety of different scenarios, and what observable effect it may have on the resulting SN. The amount of mass lost, its speed, and how soon before core collapse the material is removed can have a dramatic effect on the resulting SN light curve and spectrum. Massive stars trek across the HR diagram as they evolve, and the SN can look very different depending on where along this path core collapse occurs; it may not depend solely on initial mass. The most extreme pre-SN mass ejections in massive luminous blue variables (LBVs) have recently (and surprisingly) been linked to the very luminous Type IIn supernovae with circumstellar interaction that dominates the spectrum and enhances the visual luminosity. In some cases these objects require strong LBV-like shell ejections in the decades immediately before a SN. Strong winds or episodic mass loss of luminous red supergiants (RSGs) and yellow hypergiants may also lead to less extreme Type IIn events. Post-RSG blue supergiants like SN 1987A's progenitor and lower-luminosity LBVs like HD 168625 are also candidates for Type II SNe with visible circumstellar material. Finally, progenitors that successfully shed their H envelopes (either through LBV eruptions, strong winds, or binary mass transfer) die as Type Ib or Ic supernovae, and some of these also show evidence for immediate pre-SN shell ejections. Many of the potential progenitors of Types Ib, Ic, IIn, IIb, and II-L overlap in their range of probable initial mass, and I will point to some open questions about how they fit together in the context of stellar evolution, and the roles of mass loss and initial mass in determining their relative rates.

  11. Isotopic yield in cold binary fission of even-even 244-258Cf isotopes

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Cyriac, Annu; Krishnan, Sreejith

    2016-05-01

    The cold binary fission of even-even 244-258Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. It is found that for 244,246,248Cf isotopes highest yield is for the fragments with isotope of Pb (Z = 82) as one fragment, whereas for 250Cf and 252Cf isotopes the highest yield is for the fragments with isotope of Hg (Z = 80) as one fragment. In the case of 254,256,258Cf isotopes the highest yield is for the fragments with Sn (Z = 50) as one fragment. Thus, the fragment combinations with maximum yield reveal the role of doubly magic and near doubly magic nuclei in binary fission. It is found that asymmetric splitting is favored for Cf isotopes with mass number A ≤ 250 and symmetric splitting is favored for Cf isotopes with A > 252. In the case of Cf isotope with A = 252, there is an equal probability for asymmetric and symmetric splitting. The individual yields obtained for the cold fission of 252Cf isotope are compared with the experimental data taken from the γ- γ- γ coincidences technique using Gammasphere.

  12. Are light δ13C diamonds derived from preserved primordial heterogeneity or subducted organic carbon? Using numerical modelling of multi-component mass balanced mixing of stable isotopes

    NASA Astrophysics Data System (ADS)

    Mikhail, S.; Jones, A. P.; Robinson, S.; Milledge, H. J.; Verchovsky, A. B.

    2009-04-01

    During the subduction of oceanic crust light volatile elements such as S, C and H are recycled into the upper mantle wedge via slab dehydration and partial melting of oceanic lithosphere. This is evident as arc magmas have higher concentrations of SO2, CO2 and H2O than mid-ocean ridge basalts (Wallace, 2005). It is also calculated that 50% of the carbon and >70% of the sulphur subducted is returned to the earth's deep mantle (Wallace, 2005). This work is testing the notion that the subducted organic carbon is a possible source of growth medium for diamonds. Mantle materials display an interesting bimodality in carbon isotopes with a large peak demonstrating the mean mantle value of ~ -5 ‰ and a smaller peak consistent with organic carbon at ~ -25‰ (Deines, 2001). The source of the bimodality remains unresolved with the main theories being; subducted organic carbon, preserved primordial heterogeneity and the existence of a HPHT fractionation process (for a review see Cartigny, 2005). To test the idea that such organic values of d13C in diamond (ranging from -11 to -37‰) are derived from subducted organic carbon it is essential to compare the d13C values in diamond to other isotopic systems, such as the values for d15N in diamond, as well as values for d34S and d18O in associated syngenic mineral inclusions. We have calculated the percentage of organic C-O-N-S in sediments relative to mean mantle values for d13C, d15N, d34S and d18O required to produce the observed isotopic ratios found in natural diamonds and syngenic mineral inclusions. This was done by way of multi-component mass balanced mixing of stable isotopes between sedimentary, organic and mantle materials of varying measured isotope compositions. References: Cartigny, P .2005. Elements 1, 79-84 Deines, P. 2001. Earth Science Reviews 58, 247-278 Wallace, P.J. 2005. Journal of Volcanology and Geothermal Research 140, 217- 240

  13. Physicochemical isotope anomalies

    SciTech Connect

    Esat, T.M.

    1988-06-01

    Isotopic composition of refractory elements can be modified, by physical processes such as distillation and sputtering, in unexpected patterns. Distillation enriches the heavy isotopes in the residue and the light isotopes in the vapor. However, current models appear to be inadequate to describe the detailed mass dependence, in particular for large fractionations. Coarse- and fine-grained inclusions from the Allende meteorite exhibit correlated isotope effects in Mg both as mass-dependent fractionation and residual anomalies. This isotope pattern can be duplicated by high temperature distillation in the laboratory. A ubiquitous property of meteoritic inclusions for Mg as well as for most of the other elements, where measurements exist, is mass-dependent fractionation. In contrast, terrestrial materials such as microtektites, tektite buttons as well as lunar orange and green glass spheres have normal Mg isotopic composition. A subset of interplanetary dust particles labelled as chondritic aggregates exhibit excesses in {sup 26}Mg and deuterium anomalies. Sputtering is expected to be a dominant mechanism in the destruction of grains within interstellar dust clouds. An active proto-sun as well as the present solar-wind and solar-flare flux are of sufficient intensity to sputter significant amounts of material. Laboratory experiments in Mg show widespread isotope effects including residual {sup 26}Mg excesses and mass dependent fractionation. It is possible that the {sup 26}Mg excesses in interplanetary dust is related to sputtering by energetic solar-wind particles. The implication if the laboratory distillation and sputtering effects are discussed and contrasted with the anomalies in meteoritic inclusions the other extraterrestrial materials the authors have access to.

  14. SN Typing for the SDSS SN Survey

    SciTech Connect

    Rivers, Elizabeth S.; /Wellesley Coll. /SLAC

    2005-12-15

    In the fall of 2004 the Sloan Digital Sky Survey (SDSS) 2.5m telescope scanned the southern equatorial stripe for approximately 20 nights over the space of two months. Light curves for over four dozen supernovae (SNe) were collected over time using five colored filters ugriz that together had a range of approximately 3000{angstrom} to 10500{angstrom}. 22 SNe were spectroscopically confirmed with follow-up observation. Using the data obtained in the Fall 2004 campaign, preparations are now being made for the Supernova Survey of the SDSS II, a three-year extension of the original project. One main goal of the Supernova Survey will be to identify and study type Ia SNe of up to redshift {approx}0.4, the intermediate ''redshift desert'', as well as enabling further study of other types of SNe including type 1b/c and peculiar SNe. Most of the SNe found will not have spectra taken, due to time and cost constraints. Thus it would be advantageous to be able to robustly type SNe solely from the light curves obtained by the SDSS telescope prior to, or even without ever obtaining a spectrum. Using light curves of well-observed SNe templates were constructed for comparison with unknown SNe in order to photometrically type them.

  15. Pt/SnO2-based CO-oxidation catalysts for CO2 lasers

    NASA Technical Reports Server (NTRS)

    Upchurch, Billy T.; Schryer, David R.; Hess, Robert V.; Brown, Kenneth G.; Van Norman, John D.

    1990-01-01

    The activity of Pt/SnO2-based CO-oxidation catalysts has been maximized by optimizing pretreatment conditions and catalyst formulation. The role of H2O in activating these catalysts and of CO2 retention in deactivating them has been determined as has the interaction of these catalysts with rare-isotope C(0-18) and (O-18)2.

  16. Stages of weathering mantle formation from carbonate rocks in the light of rare earth elements (REE) and Sr-Nd-Pb isotopes

    NASA Astrophysics Data System (ADS)

    Hissler, Christophe; Stille, Peter

    2015-04-01

    Weathering mantles are widespread and include lateritic, sandy and kaolinite-rich saprolites and residuals of partially dissolved rocks. These old regolith systems have a complex history of formation and may present a polycyclic evolution due to successive geological and pedogenetic processes that affected the profile. Until now, only few studies highlighted the unusual high content of associated trace elements in weathering mantles originating from carbonate rocks, which have been poorly studied, compared to those developing on magmatic bedrocks. For instance, these enrichments can be up to five times the content of the underlying carbonate rocks. However, these studies also showed that the carbonate bedrock content only partially explains the soil enrichment for all the considered major and trace elements. Up to now, neither soil, nor saprolite formation has to our knowledge been geochemically elucidated. Therefore, the aim of this study was to examine more closely the soil forming dynamics and the relationship of the chemical soil composition to potential sources. REE distribution patterns and Sr-Nd-Pb isotope ratios have been used because they are particularly well suited to identify trace element migration, to recognize origin and mixing processes and, in addition, to decipher possible anthropogenic and/or "natural" atmosphere-derived contributions to the soil. Moreover, leaching experiments have been applied to identify mobile phases in the soil system and to yield information on the stability of trace elements and especially on their behaviour in these Fe-enriched carbonate systems. All these geochemical informations indicate that the cambisol developing on such a typical weathering mantle ("terra fusca") has been formed through weathering of a condensed Bajocian limestone-marl facies. This facies shows compared to average world carbonates important trace element enrichments. Their trace element distribution patterns are similar to those of the soil

  17. Supernova SN 2012dn: a spectroscopic clone of SN 2006gz

    NASA Astrophysics Data System (ADS)

    Chakradhari, N. K.; Sahu, D. K.; Srivastav, S.; Anupama, G. C.

    2014-09-01

    We present optical and UV analysis of the luminous Type Ia supernova SN 2012dn covering the period from ˜-11 to +109 d with respect to the B-band maximum, which occurred on JD 245 6132.89 ± 0.19, with an apparent magnitude of mB^max = 14.38 ± 0.02. The absolute magnitudes at maximum in B and V bands are MB^max = -19.52 ± 0.15 and MV^max = -19.42 ± 0.15, respectively. SN 2012dn is marginally luminous compared to normal Type Ia supernovae. The peak bolometric luminosity of log L_bol^max = 43.27 ± 0.06 erg s-1 suggests that 0.82 ± 0.12 M⊙ of 56Ni was synthesized in the explosion. The decline rate Δm15(B)true = 0.92 ± 0.04 mag is lower than that of normal Type Ia supernovae, and similar to the luminous SN 1991T. However, the photometric and spectroscopic behaviour of SN 2012dn is different from that of SN 1991T. Early-phase light curves in R and I bands are very broad. The I-band peak has a plateau-like appearance similar to the super-Chandra SN 2009dc. Pre-maximum spectra show clear evidence of C II 6580 Å line, indicating the presence of unburned materials. The velocity evolution of C II line is peculiar. Except for the very early phase (˜-13 d), the C II line velocity is lower than the velocity estimated using the Si II line. During the pre-maximum and close to the maximum phase, to reproduce observed shape of the spectra, the synthetic spectrum code SYN++ needs significantly higher blackbody temperature than those required for normal Type Ia events. The photospheric velocity evolution and other spectral properties are similar to those of the carbon-rich SN 2006gz.

  18. SN 2014J and the Harvard Observing Project

    NASA Astrophysics Data System (ADS)

    McIntosh, Melissa; Bieryla, Allyson; Newton, Elisabeth R.; Lewis, John A.; Vanderburg, Andrew; Alexander, Kate Denham; Blanchard, Peter

    2014-06-01

    A chance discovery on January 21, 2014 by Steve Fossey et al. of University College London during an undergraduate telescope training session revealed the closest type Ia supernova in the past 42 years. The bright SN 2014J was observed by undergraduates and graduate students alike in the Harvard Observing Project (see poster by A. Bieryla) with the Clay Telescope at Harvard University. Observations were obtained in multiple filters starting January 24, 2014, prior to the supernova reaching its peak brightness, and monitoring will continue as the supernova fades in brightness. We will present multiple band light curve photometry and color RGB images of SN 2014J and its host galaxy M82.

  19. (n,γ) Experiments on tin isotopes

    NASA Astrophysics Data System (ADS)

    Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Rundberg, R. S.; Rusev, G.; Ullmann, J. L.; Vieira, D. J.; Becvar, F.; Krticka, M.; Kroll, J.; Agvaanluvsan, U.; Dashdorj, D.; Erdenehuluun, B.; Tsend-Ayush, T.

    2013-04-01

    Neutron capture experiments on highly enriched 117,119Sn isotopes were performed with the DANCE detector array located at the Los Alamos Neutron Science Center. The DANCE detector provides detailed information about the multi-step γ-ray cascade following neutron capture. Analysis of the experimental data provides important information to improve understanding of the neutron capture reaction, including a test of the statistical model, the assignment of spins and parities of neutron resonances, and information concerning the Photon Strength Function (PSF) and Level Density (LD) below the neutron separation energy. Preliminary results for the (n,γ) reaction on 117,119Sn are presented. Resonance spins of the odd-A tin isotopes were almost completely unknown. Resonance spins and parities have been assigned via analysis of the multi-step γ-ray spectra and directional correlations.

  20. (n,{gamma}) Experiments on tin isotopes

    SciTech Connect

    Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Rusev, G.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Becvar, F.; Krticka, M.; Kroll, J.; Agvaanluvsan, U.; Dashdorj, D.; Erdenehuluun, B.; Tsend-Ayush, T.

    2013-04-19

    Neutron capture experiments on highly enriched {sup 117,119}Sn isotopes were performed with the DANCE detector array located at the Los Alamos Neutron Science Center. The DANCE detector provides detailed information about the multi-step {gamma}-ray cascade following neutron capture. Analysis of the experimental data provides important information to improve understanding of the neutron capture reaction, including a test of the statistical model, the assignment of spins and parities of neutron resonances, and information concerning the Photon Strength Function (PSF) and Level Density (LD) below the neutron separation energy. Preliminary results for the (n,{gamma}) reaction on {sup 117,119}Sn are presented. Resonance spins of the odd-A tin isotopes were almost completely unknown. Resonance spins and parities have been assigned via analysis of the multi-step {gamma}-ray spectra and directional correlations.

  1. Electronic Structure and Defect Physics of Tin Sulfides: SnS, Sn2S3 , and Sn S2

    NASA Astrophysics Data System (ADS)

    Kumagai, Yu; Burton, Lee A.; Walsh, Aron; Oba, Fumiyasu

    2016-07-01

    The tin sulfides SnS, Sn2S3 , and Sn S2 are investigated for a wide variety of applications such as photovoltaics, thermoelectrics, two-dimensional electronic devices, Li ion battery electrodes, and photocatalysts. For these applications, native point defects play important roles, but only those of SnS have been investigated theoretically in the literature. In this study, we consider the band structures, band-edge positions, and thermodynamical stability of the tin sulfides using a density functional that accounts for van der Waals corrections and the G W0 approximation. We revisit the point-defect properties, namely, electronic and atomic structures and energetics of defects, in SnS and newly examine those in Sn S2 and Sn2S3 with a comparison to those in SnS. We find that Sn S2 shows contrasting defect properties to SnS: Undoped SnS shows p -type behavior, whereas Sn S2 shows n type, which are mainly attributed to the tin vacancies and tin interstitials, respectively. We also find that the defect features in Sn2S3 can be described as a combination of those in SnS and Sn S2 , intrinsically Sn2S3 showing n -type behavior. However, the conversion to p type can be attained by doping with a large monovalent cation, namely, potassium. The ambipolar dopability, coupled with the earth abundance of its constituents, indicates great potential for electronic applications, including photovoltaics.

  2. Spontaneous fission of light californium isotopes produced in 206,207,208Pb + 34,36S reactions; new nuclide 238Cf

    NASA Astrophysics Data System (ADS)

    Lazarev, Yu. A.; Shirokovsky, I. V.; Utyonkov, V. K.; Tretyakova, S. P.; Kutner, V. B.

    1995-02-01

    In bombardments of 206,207,208Pb with 34S and 206Pb with 36S, we identified a new spontaneously fissioning isotope 238Cf with T sf ≈ T {1}/{2} = 21 ± 2 ms and obtained evidence of the production of a new isotope 237Cf with T {1}/{2} = 2.1 ± 0.3 s. The spontaneous-fission (SF) decay mode was established for 240Cf; its SF branch was estimated to be bsf ˜ 2 × 10 -2. We measured also bsf ⩽ 1.4 × 10 -4 for 242Cf and estimated bsf ˜ 10 -1 for 237Cf. The production cross sections of 238Cf in the 206,207,208Pb + 34S reactions were measured to be in the range of 0.3 to 1.1 nb. Finally, we probed the influence of the neutron excess in the N = 20 projectile 36S on cross sections of fusion-evaporation reactions occurring on lead targets.

  3. Anaerobic central metabolic pathways in Shewanella oneidensis MR-1interpreted in the light of isotopic metabolite labeling, enzymeactivities and genome annotation

    SciTech Connect

    Tang, Yinjie J.; Meadows, Adam L.; Kirby, James; Keasling, Jay D.

    2006-06-27

    It has been proposed that during growth under anaerobic oroxygen-limited conditions Shewanella oneidensis MR-1 uses theserine-isocitrate lyase pathway common to many methylotrophic anaerobes,in which formaldehyde produced from pyruvate is condensed with glycine toform serine. The serine is then transformed through hydroxypyruvate andglycerate to enter central metabolism at phosphoglycerate. To examine itsuse of the serine-isocitrate lyase pathway under anaerobic conditions, wegrew S. oneidensis MR-1 on [1-13C]lactate as the sole carbon source witheither trimethylamine N-oxide (TMAO) or fumarate as an electron acceptor.Analysis of cellular metabolites indicates that a large percentage(>75 percent) of lactate was partially oxidized to either acetate orpyruvate. The 13C isotope distributions in amino acids and other keymetabolites indicate that, under anaerobic conditions, a complete serinepathway is not present, and lactate is oxidized via a highly reversibleserine degradation pathway. The labeling data also suggest significantactivity in the anaplerotic (malic enzyme and phosphoenolpyruvatecarboxylase) and glyoxylate shunt (isocitrate lyase and malate synthase)reactions. Although the tricarboxylic acid (TCA) cycle is often observedto be incomplete in many other anaerobes (absence of 2-oxoglutaratedehydrogenase activity), isotopic labeling supports the existence of acomplete TCA cycle in S. oneidensis MR-1 under TMAO reductioncondition.

  4. Dead or Alive? Long-term evolution of SN 2015bh (SNhunt275)

    NASA Astrophysics Data System (ADS)

    Elias-Rosa, N.; Pastorello, A.; Benetti, S.; Cappellaro, E.; Taubenberger, S.; Terreran, G.; Fraser, M.; Brown, P. J.; Tartaglia, L.; Morales-Garoffolo, A.; Harmanen, J.; Richardson, N. D.; Artigau, É.; Tomasella, L.; Margutti, R.; Smartt, S. J.; Dennefeld, M.; Turatto, M.; Anupama, G. C.; Arbour, R.; Berton, M.; Bjorkman, K. S.; Boles, T.; Briganti, F.; Chornock, R.; Ciabattari, F.; Cortini, G.; Dimai, A.; Gerhartz, C. J.; Itagaki, K.; Kotak, R.; Mancini, R.; Martinelli, F.; Milisavljevic, D.; Misra, K.; Ochner, P.; Patnaude, D.; Polshaw, J.; Sahu, D. K.; Zaggia, S.

    2016-09-01

    Supernova (SN) 2015bh (or SNhunt275) was discovered in NGC 2770 on 2015 February with an absolute magnitude of Mr ˜ -13.4 mag, and was initially classified as a SN impostor. Here we present the photometric and spectroscopic evolution of SN 2015bh from discovery to late phases (˜ 1 yr after). In addition, we inspect archival images of the host galaxy up to ˜ 21 yr before discovery, finding a burst ˜ 1 yr before discovery, and further signatures of stellar instability until late 2014. Later on, the luminosity of the transient slowly increases, and a broad light curve peak is reached after about three months. We propose that the transient discovered in early 2015 could be a core-collapse SN explosion. The pre-SN luminosity variability history, the long-lasting rise and faintness first light curve peak suggests that the progenitor was a very massive, unstable and blue star, which exploded as a faint SN because of severe fallback of material. Later on, the object experiences a sudden brightening of 3 mag, which results from the interaction of the SN ejecta with circumstellar material formed through repeated past mass-loss events. Spectroscopic signatures of interaction are however visible at all epochs. A similar chain of events was previously proposed for the similar interacting SN 2009ip.

  5. Late-time Photometry of Type Ia Supernova SN 2012cg Reveals the Radioactive Decay of 57 Co

    NASA Astrophysics Data System (ADS)

    Graur, Or; Zurek, David; Shara, Michael M.; Riess, Adam G.; Seitenzahl, Ivo R.; Rest, Armin

    2016-03-01

    Seitenzahl et al. have predicted that roughly three years after its explosion, the light we receive from a Type Ia supernova (SN Ia) will come mostly from reprocessing of electrons and X-rays emitted by the radioactive decay chain 57Co → 57Fe, instead of positrons from the decay chain 56Co → 56Fe that dominates the SN light at earlier times. Using the Hubble Space Telescope, we followed the light curve of the SN Ia SN 2012cg out to 1055 days after maximum light. Our measurements are consistent with the light curves predicted by the contribution of energy from the reprocessing of electrons and X-rays emitted by the decay of 57Co, offering evidence that 57Co is produced in SN Ia explosions. However, the data are also consistent with a light echo ∼14 mag fainter than SN 2012cg at peak. Assuming no light-echo contamination, the mass ratio of 57Ni and 56Ni produced by the explosion, a strong constraint on any SN Ia explosion models, is {0.043}-0.011+0.012, roughly twice Solar. In the context of current explosion models, this value favors a progenitor white dwarf with a mass near the Chandrasekhar limit.

  6. Controlled fabrication of Sn/TiO2 nanorods for photoelectrochemical water splitting

    PubMed Central

    2013-01-01

    In this work, we investigate the controlled fabrication of Sn-doped TiO2 nanorods (Sn/TiO2 NRs) for photoelectrochemical water splitting. Sn is incorporated into the rutile TiO2 nanorods with Sn/Ti molar ratios ranging from 0% to 3% by a simple solvothermal synthesis method. The obtained Sn/TiO2 NRs are single crystalline with a rutile structure. The concentration of Sn in the final nanorods can be well controlled by adjusting the molar ratio of the precursors. Photoelectrochemical experiments are conducted to explore the photocatalytic activity of Sn/TiO2 NRs with different doping levels. Under the illumination of solar simulator with the light intensity of 100 mW/cm2, our measurements reveal that the photocurrent increases with increasing doping level and reaches the maximum value of 1.01 mA/cm2 at −0.4 V versus Ag/AgCl, which corresponds to up to about 50% enhancement compared with the pristine TiO2 NRs. The Mott-Schottky plots indicate that incorporation of Sn into TiO2 nanorod can significantly increase the charge carrier density, leading to enhanced conductivity of the nanorod. Furthermore, we demonstrate that Sn/TiO2 NRs can be a promising candidate for photoanode in photoelectrochemical water splitting because of their excellent chemical stability. PMID:24191909

  7. Sn vacancies in photorefractive Sn2P2S6 crystals: An electron paramagnetic resonance study of an optically active hole trap

    NASA Astrophysics Data System (ADS)

    Golden, E. M.; Basun, S. A.; Evans, D. R.; Grabar, A. A.; Stoika, I. M.; Giles, N. C.; Halliburton, L. E.

    2016-10-01

    Electron paramagnetic resonance (EPR) is used to identify the singly ionized charge state of the Sn vacancy ( VSn - ) in single crystals of Sn2P2S6 (often referred to as SPS). These vacancies, acting as a hole trap, are expected to be important participants in the photorefractive effect observed in undoped SPS crystals. In as-grown crystals, the Sn vacancies are doubly ionized ( VSn 2 - ) with no unpaired spins. They are then converted to a stable EPR-active state when an electron is removed (i.e., a hole is trapped) during an illumination below 100 K with 633 nm laser light. The resulting EPR spectrum has g-matrix principal values of 2.0079, 2.0231, and 1.9717. There are resolved hyperfine interactions with two P neighbors and one Sn neighbor. The isotropic portions of these hyperfine matrices are 167 and 79 MHz for the two 31P neighbors and 8504 MHz for the one Sn neighbor (this latter value is the average for 117Sn and 119Sn). These VSn - vacancies are shallow acceptors with the hole occupying a diffuse wave function that overlaps the neighboring Sn2+ ion and (P2S6)4- anionic unit. Using a general-order kinetics approach, an analysis of isothermal decay curves of the VSn - EPR spectrum in the 107-115 K region gives an activation energy of 283 meV.

  8. Internal oxidation of sp-Impurities in silver studied by119Sn Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Andreasen, H.; Damgaard, S.; Nielsen, H. L.; Petersen, J. W.; Weyer, G.

    1983-12-01

    The internal oxidation of the ion-implanted radioactive precursors119Cd and119Sb to the Mössbauer isotope119Sn in silver has been investigated. The oxidation is monitored by the intensity of a line in the Mössbauer spectra, which is characteristic of SnO2 (δ=(0 0.23)mm/s relative to CaSnO3, ΔEQ ≈ 0.5 mm/s, ϑ ≈ 220 K). This line is attributed to an internal oxidation of the implanted impurities by interstitially diffusing oxygen pairs. The formation and annealing kinetics of the impurity-oxygen complexes are interpreted in terms of the diffusion coefficients of oxygen and the sp-impurities in silver, respectively, and the reactivity between them. Comparison is made to Mössbauer experiments on SnAg alloys and to PAC measurements on111cd in silver.

  9. Photodetector with enhanced light absorption

    DOEpatents

    Kane, James

    1985-01-01

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  10. Optical and near-infrared observations of SN 2014ck: an outlier among the Type Iax supernovae

    NASA Astrophysics Data System (ADS)

    Tomasella, L.; Cappellaro, E.; Benetti, S.; Pastorello, A.; Hsiao, E. Y.; Sand, D. J.; Stritzinger, M.; Valenti, S.; McCully, C.; Arcavi, I.; Elias-Rosa, N.; Harmanen, J.; Harutyunyan, A.; Hosseinzadeh, G.; Howell, D. A.; Kankare, E.; Morales-Garoffolo, A.; Taddia, F.; Tartaglia, L.; Terreran, G.; Turatto, M.

    2016-06-01

    We present a comprehensive set of optical and near-infrared (NIR) photometric and spectroscopic observations for SN 2014ck, extending from pre-maximum to six months later. These data indicate that SN 2014ck is photometrically nearly identical to SN 2002cx, which is the prototype of the class of peculiar transients named SNe Iax. Similar to SN 2002cx, SN 2014ck reached a peak brightness MB = -17.37 ± 0.15 mag, with a post-maximum decline rate Δm15(B) = 1.76 ± 0.15 mag. However, the spectroscopic sequence shows similarities with SN 2008ha, which was three magnitudes fainter and faster declining. In particular, SN 2014ck exhibits extremely low ejecta velocities, ˜3000 km s-1 at maximum, which are close to the value measured for SN 2008ha and half the value inferred for SN 2002cx. The bolometric light curve of SN 2014ck is consistent with the production of 0.10^{+0.04}_{-0.03} M_{{⊙}} of 56Ni. The spectral identification of several iron-peak features, in particular Co II lines in the NIR, provides a clear link to SNe Ia. Also, the detection of narrow Si, S and C features in the pre-maximum spectra suggests a thermonuclear explosion mechanism. The late-phase spectra show a complex overlap of both permitted and forbidden Fe, Ca and Co lines. The appearance of strong [Ca II] λλ7292, 7324 again mirrors the late-time spectra of SN 2008ha and SN 2002cx. The photometric resemblance to SN 2002cx and the spectral similarities to SN 2008ha highlight the peculiarity of SN 2014ck, and the complexity and heterogeneity of the SNe Iax class.

  11. Comparative evaluation of quantitative glomerular filtration rate measured by isotopic and nonisotopic methods

    SciTech Connect

    Balachandran, S.; Toguri, A.G.; Petrusick, T.W.; Abbott, L.C.

    1981-04-01

    Good correlation of glomerular filtration rate (GFR) measured isotopically from plasma disappearance of Tc-99m-DTPA (Sn) was shown with inulin clearance, creatinine clearance, and graded radionuclide imaging. The isotopic GFR is a simple, urineless technique not requiring continuous infusion that enables one to perform simultaneous renal imaging with one radiotracer.

  12. Transuranium isotopes

    SciTech Connect

    Hoffman, D.C.

    1985-12-01

    The needs of the research community for the production of transuranium isotopes, the quantities required, the continuity of production desired, and what a new steady state neutron source would have to provide to satisfy these needs are discussed. Examples of past frontier research which need these isotopes as well as an outline of the proposed Large Einsteinium Activation Program, LEAP, which requires roughly ten times the current production of /sup 254/Es are given. 15 refs., 5 figs., 4 tabs.

  13. Isotopic Paleoclimatology

    NASA Astrophysics Data System (ADS)

    Bowen, R.

    Paleotemperature scales were calculated by H. C. Urey and others in the 1950s to assess past temperatures, and later work using the stable isotopes of oxygen, hydrogen, and carbon employed standards such as Peedee belemnite (PDB) and Standard Mean Ocean Water (SMOW). Subsequently, subjects as diverse as ice volume and paleotemperatures, oceanic ice and sediment cores, Pleistocene/Holocene climatic changes, and isotope chronostratigraphy extending back to the Precambrian were investigated.

  14. Isotopic chirality

    SciTech Connect

    Floss, H.G.

    1994-12-01

    This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.

  15. Optical studies of Type IIb SN 2011dh

    NASA Astrophysics Data System (ADS)

    Sahu, D. K.; Anupama, G. C.; Chakradhari, N. K.

    2014-01-01

    UBVRI photometry and low resolution optical spectroscopy of the type IIb SN 2011dh in M51 are presented, covering the first year after the explosion. The peak absolute magnitude in V-band of -17.12+/-0.18 mag indicates SN 2011dh to be a normal bright type IIb event. The peak quasi-bolometric luminosity indicates that ~ 0.06 M⊙ of 56Ni was synthesized in the explosion. The He I lines were detected in the spectra much before the maximum light in B-band. The nebular spectra of SN 2011dh show a box shaped emission in the red wing of [OI] 6300, 6363 line due to Hα emission excited because of shock-wave interaction. The analysis of the nebular spectra indicates a progenitor with a main sequence mass of 10-15 M⊙.

  16. Germanium tin light emitters on silicon

    NASA Astrophysics Data System (ADS)

    Kasper, Erich; Oehme, Michael

    2015-04-01

    The energy and emission intensity of room temperature GeSn light emitting diodes based on Ge/GeSn/Ge pin heterostructures on Si substrates were investigated as function of Sn content for two series with different material properties. For good quality GeSn diodes an increase in emission intensity by a factor two compared to Ge diodes was measured and interpreted as proof of the reduction of the energy difference between indirect and direct bandgap. Compressive strain and nonradiative recombination were named as main obstacles for stronger emission intensities which are needed for electrically stimulated laser operation.

  17. Zinc isotopic compositions of breast cancer tissue.

    PubMed

    Larner, Fiona; Woodley, Laura N; Shousha, Sami; Moyes, Ashley; Humphreys-Williams, Emma; Strekopytov, Stanislav; Halliday, Alex N; Rehkämper, Mark; Coombes, R Charles

    2015-01-01

    An early diagnostic biomarker for breast cancer is essential to improve outcome. High precision isotopic analysis, originating in Earth sciences, can detect very small shifts in metal pathways. For the first time, the natural intrinsic Zn isotopic compositions of various tissues in breast cancer patients and controls were determined. Breast cancer tumours were found to have a significantly lighter Zn isotopic composition than the blood, serum and healthy breast tissue in both groups. The Zn isotopic lightness in tumours suggests that sulphur rich metallothionein dominates the isotopic selectivity of a breast tissue cell, rather than Zn-specific proteins. This reveals a possible mechanism of Zn delivery to Zn-sequestering vesicles by metallothionein, and is supported by a similar signature observed in the copper isotopic compositions of one breast cancer patient. This change in intrinsic isotopic compositions due to cancer has the potential to provide a novel early biomarker for breast cancer.

  18. Interfacial hydrothermal synthesis of SnO{sub 2} nanorods towards photocatalytic degradation of methyl orange

    SciTech Connect

    Hou, L.R. Lian, L.; Zhou, L.; Zhang, L.H.; Yuan, C.Z.

    2014-12-15

    Highlights: • Efficient interfacial hydrothermal strategy was developed. • 1D SnO{sub 2} nanorods as an advanced photocatalyst. • SnO{sub 2} nanorods exhibit photocatalytic degradation of the MO. - Abstract: One-dimensional (1D) SnO{sub 2} nanorods (NRs) have been successfully synthesized by means of an efficient interfacial hydrothermal strategy. The resulting product was physically characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscope, etc. The as-fabricated SnO{sub 2} NRs exhibited excellent photocatalytic degradation of the methyl orange with high degradation efficiency of 99.3% with only 60 min ultra violet light irradiation. Meanwhile, the 1D SnO{sub 2} NRs exhibited intriguing photostability after four recycles.

  19. Hubble Space Telescope and Ground-based Observations of the Type Iax Supernovae SN 2005hk and SN 2008A

    NASA Astrophysics Data System (ADS)

    McCully, Curtis; Jha, Saurabh W.; Foley, Ryan J.; Chornock, Ryan; Holtzman, Jon A.; Balam, David D.; Branch, David; Filippenko, Alexei V.; Frieman, Joshua; Fynbo, Johan; Galbany, Lluis; Ganeshalingam, Mohan; Garnavich, Peter M.; Graham, Melissa L.; Hsiao, Eric Y.; Leloudas, Giorgos; Leonard, Douglas C.; Li, Weidong; Riess, Adam G.; Sako, Masao; Schneider, Donald P.; Silverman, Jeffrey M.; Sollerman, Jesper; Steele, Thea N.; Thomas, Rollin C.; Wheeler, J. Craig; Zheng, Chen

    2014-05-01

    We present Hubble Space Telescope (HST) and ground-based optical and near-infrared observations of SN 2005hk and SN 2008A, typical members of the Type Iax class of supernovae (SNe). Here we focus on late-time observations, where these objects deviate most dramatically from all other SN types. Instead of the dominant nebular emission lines that are observed in other SNe at late phases, spectra of SNe 2005hk and 2008A show lines of Fe II, Ca II, and Fe I more than a year past maximum light, along with narrow [Fe II] and [Ca II] emission. We use spectral features to constrain the temperature and density of the ejecta, and find high densities at late times, with ne >~ 109 cm-3. Such high densities should yield enhanced cooling of the ejecta, making these objects good candidates to observe the expected "infrared catastrophe," a generic feature of SN Ia models. However, our HST photometry of SN 2008A does not match the predictions of an infrared catastrophe. Moreover, our HST observations rule out a "complete deflagration" that fully disrupts the white dwarf for these peculiar SNe, showing no evidence for unburned material at late times. Deflagration explosion models that leave behind a bound remnant can match some of the observed properties of SNe Iax, but no published model is consistent with all of our observations of SNe 2005hk and 2008A.

  20. Hubble space telescope and ground-based observations of the type Iax supernovae SN 2005hk and SN 2008A

    SciTech Connect

    McCully, Curtis; Jha, Saurabh W.; Foley, Ryan J.; Chornock, Ryan; Holtzman, Jon A.; Balam, David D.; Branch, David; Filippenko, Alexei V.; Ganeshalingam, Mohan; Li, Weidong; Frieman, Joshua; Fynbo, Johan; Leloudas, Giorgos; Galbany, Lluis; Garnavich, Peter M.; Graham, Melissa L.; Hsiao, Eric Y.; Leonard, Douglas C.; and others

    2014-05-10

    We present Hubble Space Telescope (HST) and ground-based optical and near-infrared observations of SN 2005hk and SN 2008A, typical members of the Type Iax class of supernovae (SNe). Here we focus on late-time observations, where these objects deviate most dramatically from all other SN types. Instead of the dominant nebular emission lines that are observed in other SNe at late phases, spectra of SNe 2005hk and 2008A show lines of Fe II, Ca II, and Fe I more than a year past maximum light, along with narrow [Fe II] and [Ca II] emission. We use spectral features to constrain the temperature and density of the ejecta, and find high densities at late times, with n{sub e} ≳ 10{sup 9} cm{sup –3}. Such high densities should yield enhanced cooling of the ejecta, making these objects good candidates to observe the expected 'infrared catastrophe', a generic feature of SN Ia models. However, our HST photometry of SN 2008A does not match the predictions of an infrared catastrophe. Moreover, our HST observations rule out a 'complete deflagration' that fully disrupts the white dwarf for these peculiar SNe, showing no evidence for unburned material at late times. Deflagration explosion models that leave behind a bound remnant can match some of the observed properties of SNe Iax, but no published model is consistent with all of our observations of SNe 2005hk and 2008A.

  1. Modeling Type IIn Supernova Light Curves

    NASA Astrophysics Data System (ADS)

    De La Rosa, Janie; Roming, Peter; Fryer, Chris

    2016-01-01

    We present near-by Type IIn supernovae observed with Swift's Ultraviolet/Optical Telescope (UVOT). Based on the diversity of optical light curve properties, this Type II subclass is commonly referred to as heterogeneous. At the time of discovery, our IIn sample is ~ 2 magnitudes brighter at ultraviolet wavelengths than at optical wavelengths, and ultraviolet brightness decays faster than the optical brightness. We use a semi-analytical supernova (SN) model to better understand our IIn observations, and focus on matching specific observed light curves features, i.e peak luminosity and decay rate. The SN models are used to study the effects of initial SN conditions on early light curves, and to show the extent of the "uniqueness" problem in SN light curves. We gratefully acknowledge the contributions from members of the Swift UVOT team, the NASA astrophysics archival data analysis program, and the NASA Swift guest investigator program.

  2. Quadrupole collectivity of neutron-rich nuclei around 132Sn

    NASA Astrophysics Data System (ADS)

    Kröll, Th.; Behrens, T.; Krücken, R.; Bildstein, V.; Faestermann, T.; Gernhäuser, R.; Mahgoub, M.; Maierbeck, P.; Münch, M.; Weinzierl, W.; Ames, F.; Habs, D.; Kester, O.; Lutter, R.; Morgan, T.; Pasini, M.; Rudolph, K.; Thirolf, P.; Diriken, J.; Huyse, M.; Ivanov, O.; Mayet, P.; Patronis, N.; Stefanescu, I.; van de Walle, J.; van Duppen, P.; Niedermaier, O.; Scheit, H.; Schwalm, D.; Eberth, J.; Finke, F.; Martin, D.; Reiter, P.; Scherillo, A.; Seidlitz, M.; Warr, N.; Weisshaar, D.; Iwanicki, J.; Butler, P.; Cederkäll, J.; Clément, E.; Delahaye, P.; Fraile, L. M.; Georgiev, G.; Köster, U.; Sieber, T.; Voulot, D.; Wenander, F.; Franchoo, S.; Hurst, A.; Ekström, A.; Kent, P. E.; Speidel, K.-H.; Leske, J.; Schielke, S.; Jungclaus, A.; Modamio, V.; Walker, J.; Coquard, L.; Pantea, M.; Pietralla, N.; Davinson, T.; Nardelli, S.

    2008-05-01

    We report on the ``safe'' Coulomb excitation of neutron-rich Cd, Xe, and Ba isotopes in the vicinity of the doubly-magic nucleus 132Sn. The radioactive nuclei have been produced by ISOLDE at CERN and postaccelerated by the REX-ISOLDE facility. The γ-decay of excited states has been detected by the MINIBALL array. The presented preliminary results for the B(E2) values are consistent with expectations from phenomenological systematics and will be compared with theoretical calculations.

  3. Molybdenum Isotopes and Soil Processes

    NASA Astrophysics Data System (ADS)

    Siebert, C.; Pett-Ridge, J. C.; Halliday, A. N.; Burton, K. W.

    2011-12-01

    The oxygenation state of Earth's oceans is a driver of evolution and extinction events as well as climate change. In recent years stable isotope fractionation of redox sensitive elements such as molybdenum (Mo) have been used as quantitative tracers of past redox-conditions in a number of marine environments. However, little is known about the processes controlling the Mo isotope compositions of the riverine inputs to the oceans and their short- and long-term variations. Several recent studies [Archer & Vance, 2008; Pearce et al., 2010] have shown that many river waters have heavy Mo isotope compositions. In some terrestrial weathering environments dissolved Mo isotope compositions in rivers are controlled by the catchment lithology [Neubert et al., 2011]. However, many rivers show fractionation of Mo isotopes relative to their catchment lithology. Possible mechanisms causing this fractionation are chemical weathering and pedogenic processes. This study has investigated the behavior of Mo isotopes during weathering of basalt under different conditions. Results from oxic to reducing soil profiles in Hawaii show that redox conditions during soil formation can control Mo isotope compositions in soils. Reducing soil profiles have light isotope compositions whereas oxidizing profiles are heavy. This general isotope behavior is confirmed by results from soil profiles from Iceland. Here reducing layers within the profiles show marked negative isotope excursions. In oxic profiles a surprisingly strong interaction of Mo with organic matter can be observed producing significant Mo isotope fractionation. This behavior might explain long term retention of Mo in soils besides its high mobility in molybdate form. Mo associated with organic matter is bioavailable and essential for processes like nitrogen fixation. In addition, we observe that fractionation relative to the source rock is dependent on the degree of weathering, i.e. relatively un-weathered profiles do not show

  4. A 3D view of the SN 1987A Ejecta

    NASA Astrophysics Data System (ADS)

    Fransson, Claes

    2013-10-01

    SN 1987A represents the most important source of information about the explosion physics of any SN. For this the morphology of the ejecta is together with the radioactive isotopes the best diagnostics. From HST imaging in H-alpha and NIR AO imaging in Si/Fe at 1.64 mu one finds completely different morphologies, with the 1.64 mu image dominated by the processed core and H-alpha by the surrounding H envelope. Besides Cas A (Type IIb), this is the only core collapse SN where we have this information. We propose to use STIS to map the debris in SN 1987A in 3D with the best possible angular resolution. There has been no such STIS map since 2004, while the physics of the emission has undergone some profound changes. From being powered by radioactivity the energy input is now dominated by X-rays from the collision with the circumstellar ring. Compared to 2004 the 3D structure can be determined with a factor of 3 better spatial resolution and also better spectral resolution. The 3D structure in H-alpha can also give independent clues to where the large mass of dust detected by Herschel is located as well as its properties. It also gives a complementary view of the ejecta to the future ALMA imaging in CO which will have similar spatial resolution. Besides the debris we will be able to probe the 10,000 km/s reverse shock close to the ring in H-alpha. By observing this also in Ly-alpha one may test different emission processes which have been proposed, as well as probing the region producing the synchrotron emission observed by ALMA. The opportunity to observe the SN in this stage will never come back

  5. ISOTOPE SEPARATORS

    DOEpatents

    Bacon, C.G.

    1958-08-26

    An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

  6. On Type IIn/Ia-CSM supernovae as exemplified by SN 2012ca*

    NASA Astrophysics Data System (ADS)

    Inserra, C.; Fraser, M.; Smartt, S. J.; Benetti, S.; Chen, T.-W.; Childress, M.; Gal-Yam, A.; Howell, D. A.; Kangas, T.; Pignata, G.; Polshaw, J.; Sullivan, M.; Smith, K. W.; Valenti, S.; Young, D. R.; Parker, S.; Seccull, T.; McCrum, M.

    2016-07-01

    We present the complete set of ultra-violet, optical and near-infrared photometry and spectroscopy for SN 2012ca, covering the period from 6 d prior to maximum light, until 531 d after maximum. The spectroscopic time series for SN 2012ca is essentially unchanged over 1.5 yr, and appear to be dominated at all epochs by signatures of interaction with a dense circumstellar medium (CSM) rather than the underlying supernova (SN). SN 2012ca is a member of the set of type of the ambiguous IIn/Ia-CSM SNe, the nature of which have been debated extensively in the literature. The two leading scenarios are either a Type Ia SN exploding within a dense CSM from a non-degenerate, evolved companion, or a core-collapse SN from a massive star. While some members of the population have been unequivocally associated with Type Ia SNe, in other cases the association is less certain. While it is possible that SN 2012ca does arise from a thermonuclear SN, this would require a relatively high (between 20 and 70 per cent) efficiency in converting kinetic energy to optical luminosity, and a massive (˜2.3-2.6 M⊙) circumstellar medium. On the basis of energetics, and the results of simple modelling, we suggest that SN 2012ca is more likely associated with a core-collapse SN. This would imply that the observed set of similar SNe to SN 2012ca is in fact originated by two populations, and while these are drawn from physically distinct channels, they can have observationally similar properties.

  7. One year of monitoring of the Type IIb supernova SN 2011dh

    NASA Astrophysics Data System (ADS)

    Sahu, D. K.; Anupama, G. C.; Chakradhari, N. K.

    2013-07-01

    Optical UBVRI photometry and low-resolution spectroscopy of the Type IIb supernova SN 2011dh in M51 are presented, covering the first year after the explosion. The light curve and spectral evolution are discussed. The early phase light-curve evolution of SN 2011dh is very similar to SN 1993J and SN 2008ax. In the late phase, however, SN 2011dh declines faster than SN 1993J. The late phase decline in the B band is steeper than in the R and I bands, indicating the possibility of dust formation. With a peak V-band absolute magnitude of MV = -17.123 ± 0.18 mag, SN 2011dh is a marginally faint type IIb event. The reddening corrected colour curves of SN 2011dh are found to be redder than other well-studied Type IIb supernovae. The bolometric light curve indicates ˜0.09 M⊙ of 56Ni is synthesized during the explosion. The He I lines were detected in the spectra during the rise to maximum. The nebular spectra of SN 2011dh show a box-shaped emission in the red wing of the [O I] 6300-6363 Å feature, that is attributed to Hα emission from a shock-excited circumstellar material. The analysis of nebular spectra indicates that ˜0.2 M⊙ of oxygen was ejected during the explosion. Further, the [Ca II]/[O I] line ratio in the nebular phase is ˜0.7, indicating a progenitor with a main-sequence mass of 10-15 M⊙.

  8. Structures of tin cluster cations Sn3+ to Sn15+

    NASA Astrophysics Data System (ADS)

    Drebov, Nedko; Oger, Esther; Rapps, Thomas; Kelting, Rebecca; Schooss, Detlef; Weis, Patrick; Kappes, Manfred M.; Ahlrichs, Reinhart

    2010-12-01

    We employ a combination of ion mobility measurements and an unbiased systematic structure search with density functional theory methods to study structure and energetics of gas phase tin cluster cations, {Snn}^+, in the range of n = 3-15. For {Sn_{13}}^+ we also carry out trapped ion electron diffraction measurements to ascertain the results obtained by the other procedures. The structures for the smaller systems are most easily described by idealized point group symmetries, although they are all Jahn-Teller distorted: D_{3h} (trigonal bipyramid), D_{4h} (octahedron), D_{5h} (pentagonal bipyramid) for n = 5, 6, and 7. For the larger systems we find capped D_{5h} for {Sn8}^+ and {Sn9}^+, D_{3h} (tricapped trigonal prism) and D_{4d} (bicapped squared antiprism) plus adatoms for n = 10, 11, 14, and 15. A centered icosahedron with a peripheral atom removed is the dominant motif in {Sn_{12}}^+. For {Sn_{13}}^+ the calculations predict a family of virtually isoenergetic isomers, an icosahedron and slightly distorted icosahedra, which are about 0.25 eV below two C_1 structures. The experiments indicate the presence of two structures, one from the I_h family and a prolate C_1 isomer based on fused deltahedral moieties.

  9. XRF 100316D/SN 2010bh AND THE NATURE OF GAMMA-RAY BURST SUPERNOVAE

    SciTech Connect

    Cano, Z.; Bersier, D.; Guidorzi, C.; Kobayashi, S.; Melandri, A.; Mundell, C. G.; Levan, A. J.; Tanvir, N. R.; Wiersema, K.; D'Avanzo, P.; Margutti, R.; Fruchter, A. S.; Garnavich, P.; Gomboc, A.; Kopac, D.; Gorosabel, J.; Kasen, D.; Mazzali, P. A.; Nugent, P. E.; Pian, E.

    2011-10-10

    We present ground-based and Hubble Space Telescope optical and infrared observations of Swift XRF 100316D/SN 2010bh. It is seen that the optical light curves of SN 2010bh evolve at a faster rate than the archetype gamma-ray burst supernova (GRB-SN) 1998bw, but at a similar rate to SN 2006aj, an SN that was spectroscopically linked with XRF 060218, and at a similar rate to the non-GRB associated Type Ic SN 1994I. We estimate the rest-frame extinction of this event from our optical data to be E(B - V) = 0.18 {+-} 0.08 mag. We find the V-band absolute magnitude of SN 2010bh to be M{sub V} = -18.62 {+-} 0.08, which is the faintest peak V-band magnitude observed to date for spectroscopically confirmed GRB-SNe. When we investigate the origin of the flux at t - t{sub 0} = 0.598 days, it is shown that the light is not synchrotron in origin, but is likely coming from the SN shock breakout. We then use our optical and infrared data to create a quasi-bolometric light curve of SN 2010bh, which we model with a simple analytical formula. The results of our modeling imply that SN 2010bh synthesized a nickel mass of M{sub Ni} {approx} 0.1 M{sub sun}, ejected M{sub ej} {approx} 2.2 M{sub sun}, and has an explosion energy of E{sub k} {approx} 1.4 x 10{sup 52} erg. Thus, while SN 2010bh is an energetic explosion, the amount of nickel created during the explosion is much less than that of SN 1998bw and only marginally more than SN 1994I. Finally, for a sample of 22 GRB-SNe we check for a correlation between the stretch factors and luminosity factors in the R band and conclude that no statistically significant correlation exists.

  10. Comparative analysis of SN 2012dn optical spectra: days -14 to +114

    NASA Astrophysics Data System (ADS)

    Parrent, J. T.; Howell, D. A.; Fesen, R. A.; Parker, S.; Bianco, F. B.; Dilday, B.; Sand, D.; Valenti, S.; Vinkó, J.; Berlind, P.; Challis, P.; Milisavljevic, D.; Sanders, N.; Marion, G. H.; Wheeler, J. C.; Brown, P.; Calkins, M. L.; Friesen, B.; Kirshner, R.; Pritchard, T.; Quimby, R.; Roming, P.

    2016-04-01

    SN 2012dn is a super-Chandrasekhar mass candidate in a purportedly normal spiral (SAcd) galaxy, and poses a challenge for theories of type Ia supernova diversity. Here we utilize the fast and highly parametrized spectrum synthesis tool, SYNAPPS, to estimate relative expansion velocities of species inferred from optical spectra obtained with six facilities. As with previous studies of normal SN Ia, we find that both unburned carbon and intermediate-mass elements are spatially coincident within the ejecta near and below 14 000 km s-1. Although the upper limit on SN 2012dn's peak luminosity is comparable to some of the most luminous normal SN Ia, we find a progenitor mass exceeding ˜1.6 M⊙ is not strongly favoured by leading merger models since these models do not accurately predict spectroscopic observations of SN 2012dn and more normal events. In addition, a comparison of light curves and host-galaxy masses for a sample of literature and Palomar Transient Factory SN Ia reveals a diverse distribution of SN Ia subtypes where carbon-rich material remains unburned in some instances. Such events include SN 1991T, 1997br, and 1999aa where trace signatures of C III at optical wavelengths are presumably detected.

  11. Photometric type Ia supernova candidates from the three-year SDSS-II SN survey data

    SciTech Connect

    Sako, Masao; Bassett, Bruce; Connolly, Brian; Dilday, Benjamin; Cambell, Heather; Frieman, Joshua A.; Gladney, Larry; Kessler, Richard; Lampeitl, Hubert; Marriner, John; Miquel, Ramon; /Barcelona, IFAE /ICREA, Barcelona /Portsmouth U., ICG

    2011-07-01

    We analyze the three-year Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey data and identify a sample of 1070 photometric Type Ia supernova (SN Ia) candidates based on their multiband light curve data. This sample consists of SN candidates with no spectroscopic confirmation, with a subset of 210 candidates having spectroscopic redshifts of their host galaxies measured while the remaining 860 candidates are purely photometric in their identification. We describe a method for estimating the efficiency and purity of photometric SN Ia classification when spectroscopic confirmation of only a limited sample is available, and demonstrate that SN Ia candidates from SDSS-II can be identified photometrically with {approx}91% efficiency and with a contamination of {approx}6%. Although this is the largest uniform sample of SN candidates to date for studying photometric identification, we find that a larger spectroscopic sample of contaminating sources is required to obtain a better characterization of the background events. A Hubble diagram using SN candidates with no spectroscopic confirmation, but with host galaxy spectroscopic redshifts, yields a distance modulus dispersion that is only {approx}20%-40% larger than that of the spectroscopically confirmed SN Ia sample alone with no significant bias. A Hubble diagram with purely photometric classification and redshift-distance measurements, however, exhibits biases that require further investigation for precision cosmology.

  12. Shell model based Coulomb excitation γ-ray intensity calculations in 107Sn

    NASA Astrophysics Data System (ADS)

    DiJulio, D. D.; Cederkall, J.; Ekström, A.; Fahlander, C.; Hjorth-Jensen, M.

    2012-10-01

    In this work, we present recent shell model calculations, based on a realistic nucleon-nucleon interaction, for the light 107, 109Sn nuclei. By combining the calculations with the semi-classical Coulomb excitation code GOSIA, a set of γ-ray intensities has been generated. The calculated intensities are compared with the data from recent Coulomb excitation studies in inverse kinematics at the REX-ISOLDE facility with the nucleus 107Sn. The results are discussed in the context of the ordering of the single-particle orbits relative to 100Sn.

  13. THEORETICAL AND EXPERIMENTAL ASPECTS OF ISOTOPIC FRACTIONATION.

    USGS Publications Warehouse

    O'Neil, James R.

    1986-01-01

    Essential to the interpretation of natural variations of light stable isotope ratios is knowledge of the magnitude and temperature dependence of isotopic fractionation factors between the common minerals and fluids. These fractionation factors are obtained in three ways: (1) Semi-empirical calculations using spectroscopic data and the methods of statistical mechanics. (2) Laboratory calibration studies. (3) Measurements of natural samples whose formation conditions are well-known or highly constrained. In this chapter methods (1) and (2) are evaluated and a review is given of the present state of knowledge of the theory of isotopic fractionation and the fraction that influence the isotopic properties of minerals.

  14. Z =50 core stability in 110Sn from magnetic-moment and lifetime measurements

    NASA Astrophysics Data System (ADS)

    Kumbartzki, G. J.; Benczer-Koller, N.; Speidel, K.-H.; Torres, D. A.; Allmond, J. M.; Fallon, P.; Abramovic, I.; Bernstein, L. A.; Bevins, J. E.; Crawford, H. L.; Guevara, Z. E.; Gürdal, G.; Hurst, A. M.; Kirsch, L.; Laplace, T. A.; Lo, A.; Matthews, E. F.; Mayers, I.; Phair, L. W.; Ramirez, F.; Robinson, S. J. Q.; Sharon, Y. Y.; Wiens, A.

    2016-04-01

    Background: The structure of the semimagic 50Sn isotopes were previously studied via measurements of B (E 2 ;21+→01+ ) and g factors of 21+ states. The values of the B (E 2 ;21+ ) in the isotopes below midshell at N = 66 show an enhancement in collectivity, contrary to predictions from shell-model calculations. Purpose: This work presents the first measurement of the 2 1+ and 4 1+ states' magnetic moments in the unstable neutron-deficient 110Sn. The g factors provide complementary structure information to the interpretation of the observed B (E 2 ) values. Methods: The 110Sn nuclei have been produced in inverse kinematics in an α -particle transfer reaction from 12C to 106Cd projectiles at 390, 400, and 410 MeV. The g factors have been measured with the transient field technique. Lifetimes have been determined from line shapes using the Doppler-shift attenuation method. Results: The g factors of the 21+ and 41+ states in 110Sn are g (21+) = +0.29(11) and g (41+) = +0.05(14), respectively. In addition, the g (41+) = +0.27(6) in 106Cd has been measured for the first time. A line-shape analysis yielded τ (110Sn ; 21+) = 0.81(10) ps and a lifetime of τ (110Sn ; 31-) = 0.25(5) ps was calculated from the fully Doppler-shifted γ line. Conclusions: No evidence has been found in 110Sn that would require excitation of protons from the closed Z =50 core.

  15. Aligned epitaxial SnO2 nanowires on sapphire: growth and device applications.

    PubMed

    Wang, Xiaoli; Aroonyadet, Noppadol; Zhang, Yuzheng; Mecklenburg, Matthew; Fang, Xin; Chen, Haitian; Goo, Edward; Zhou, Chongwu

    2014-06-11

    Semiconducting SnO2 nanowires have been used to demonstrate high-quality field-effect transistors, optically transparent devices, photodetectors, and gas sensors. However, controllable assembly of rutile SnO2 nanowires is necessary for scalable and practical device applications. Here, we demonstrate aligned, planar SnO2 nanowires grown on A-plane, M-plane, and R-plane sapphire substrates. These parallel nanowires can reach 100 μm in length with sufficient density to be patterned photolithographically for field-effect transistors and sensor devices. As proof-of-concept, we show that transistors made this way can achieve on/off current ratios on the order of 10(6), mobilities around 71.68 cm(2)/V·s, and sufficiently high currents to drive external organic light-emitting diode displays. Furthermore, the aligned SnO2 nanowire devices are shown to be photosensitive to UV light with the capability to distinguish between 254 and 365 nm wavelengths. Their alignment is advantageous for polarized UV light detection; we have measured a polarization ratio of photoconductance (σ) of 0.3. Lastly, we show that the nanowires can detect NO2 at a concentration of 0.2 ppb, making them a scalable, ultrasensitive gas sensing technology. Aligned SnO2 nanowires offer a straightforward method to fabricate scalable SnO2 nanodevices for a variety of future electronic applications.

  16. Sub-Barrier Coulomb Excitation of 106,108,110Sn

    NASA Astrophysics Data System (ADS)

    Ekström, A.; Cederkäll, J.; Fahlander, C.; Hjorth-Jensen, M.; Ames, F.; Butler, P. A.; Davinson, T.; Eberth, J.; Georgiev, G.; Gorgen, A.; Górska, M.; Habs, D.; Huyse, M.; Ivanov, O.; Iwanicki, J.; Kester, O.; Köster, U.; Marsh, B. A.; Reiter, P.; Scheit, H.; Schwalm, D.; Siem, S.; Stefanescu, I.; Tveten, G. M.; van de Walle, J.; van Duppen, P.; Voulot, D.; Warr, N.; Weisshaar, D.; Wenander, F.; Zielinska, M.

    2008-05-01

    The reduced transition probabilities between the first excited 2+ state and the 0+ ground state, B(E20+-->2+), have been measured in 106,108,110Sn using sub-barrier Coulomb excitation in inverse kinematics at REX-ISOLDE. The results are, B(E20+-->2+) = 0.220(22), 0.226(17), and 0.228(32)e2b2, for 110Sn, 108Sn, and 106Sn, respectively. The results for 106,108Sn are preliminary. De-excitation γ-rays were detected by the MINIBALL Ge-array. The B(E2) reveals detailed information about the nuclear wave function. A shell model prediction based on an effective CD-Bonn interaction in the ν(0g7/2,2s,1d,0h11/2) model space using eeffν = 1.0 e follows the experimental values for the neutron rich Sn isotopes, but fails to reproduce the results presented here.

  17. LEGUS Discovery of a Light Echo Around Supernova 2012aw

    NASA Astrophysics Data System (ADS)

    Van Dyk, Schuyler D.; Lee, Janice C.; Anderson, Jay; Andrews, Jennifer E.; Calzetti, Daniela; Bright, Stacey N.; Ubeda, Leonardo; Smith, Linda J.; Sabbi, Elena; Grebel, Eva K.; Herrero, Artemio; de Mink, Selma E.

    2015-06-01

    We have discovered a luminous light echo around the normal Type II-Plateau Supernova (SN) 2012aw in Messier 95 (M95; NGC 3351), detected in images obtained approximately two years after explosion with the Wide Field Channel 3 on board the Hubble Space Telescope by the Legacy ExtraGalactic Ultraviolet Survey. The multi-band observations span from the near-ultraviolet through the optical (F275W, F336W, F438W, F555W, and F814W). The apparent brightness of the echo at the time was ˜21-22 mag in all of these bands. The echo appears circular, although less obviously as a ring, with an inhomogeneous surface brightness, in particular, a prominent enhanced brightness to the southeast. The SN itself was still detectable, particularly in the redder bands. We are able to model the light echo as the time-integrated SN light scattered off of diffuse interstellar dust in the SN environment. We have assumed that this dust is analogous to that in the Milky Way with {R}V=3.1. The SN light curves that we consider also include models of the unobserved early burst of light from the SN shock breakout. Our analysis of the echo suggests that the distance from the SN to the scattering dust elements along the echo is ≈ 45 pc. The implied visual extinction for the echo-producing dust is consistent with estimates made previously from the SN itself. Finally, our estimate of the SN brightness in F814W is fainter than that measured for the red supergiant star at the precise SN location in pre-SN images, possibly indicating that the star has vanished and confirming it as the likely SN progenitor.

  18. OPTICAL AND INFRARED ANALYSIS OF TYPE II SN 2006bc

    SciTech Connect

    Gallagher, Joseph S.; Sugerman, B. E. K.; Clayton, Geoffrey C.; Andrews, J. E.; Clem, J. E-mail: ben.sugerman@goucher.edu E-mail: jandrews@phys.lsu.edu; and others

    2012-07-10

    We present nebular phase optical imaging and spectroscopy and near/mid-IR imaging of the Type II SN 2006bc. Observations reveal the central wavelength of the symmetric H{alpha} line profile to be redshifted with respect to the host galaxy H{alpha} emission by day 325. Such a phenomenon has been argued to result from an asymmetric explosion in the iron-peak elements resulting in a larger mass of {sup 56}Ni and higher excitation of hydrogen on the far side of the supernova (SN) explosion. We also observe a gradual blueshifting of this H{alpha} peak which is indicative of dust formation in the ejecta. Although showing a normal peak brightness, V {approx} -17.2, for a core-collapse SN, 2006bc fades by {approx}6 mag during the first 400 days suggesting either a relatively low {sup 56}Ni yield, an increase in extinction due to new dust, or both. A short-duration flattening of the light curve is observed from day 416 to day 541 suggesting an optical light echo. Based on the narrow time window of this echo, we discuss implications on the location and geometry of the reflecting interstellar medium. With our radiative transfer models, we find an upper limit of 2 Multiplication-Sign 10{sup -3} M{sub Sun} of dust around SN 2006bc. In the event that all of this dust were formed during the SN explosion, this quantity of dust is still several orders of magnitude lower than that needed to explain the large quantities of dust observed in the early universe.

  19. Possible isotopic fractionation effects in sputtered minerals

    NASA Technical Reports Server (NTRS)

    Haff, P. K.; Watson, C. C.; Tombrello, T. A.

    1980-01-01

    A model which makes definite predictions for the fractionation of isotopes in sputtered material is discussed. The fractionation patterns are nonlinear, and the pattern for a particular set of isotopes depends on the chemical matrix within which those isotopes are contained. Calculations are presented for all nonmonoisotopic elements contained in the minerals perovskite, anorthite, ackermanite, enstatite, and troilite. All isotopes are fractionated at the level of approximately 4-6 deg/o per atomic mass unit. Oxygen is always positively fractionated (heavier isotopes sputtered preferentially), and heavier elements are generally negatively fractioned (light isotopes sputtered preferentially). The value of Delta (O-18:O-16) is always less by about 1.8 deg/o than a linear extrapolation based upon the calculated delta (O-17:O-16) value would suggest. The phenomenon of both negative and positive fractionation patterns from a single target mineral are used to make an experimental test of the proposed model.

  20. High thermoelectric performance of p-type SnTe via a synergistic band engineering and nanostructuring approach.

    PubMed

    Tan, Gangjian; Zhao, Li-Dong; Shi, Fengyuan; Doak, Jeff W; Lo, Shih-Han; Sun, Hui; Wolverton, Chris; Dravid, Vinayak P; Uher, Ctirad; Kanatzidis, Mercouri G

    2014-05-14

    SnTe is a potentially attractive thermoelectric because it is the lead-free rock-salt analogue of PbTe. However, SnTe is a poor thermoelectric material because of its high hole concentration arising from inherent Sn vacancies in the lattice and its very high electrical and thermal conductivity. In this study, we demonstrate that SnTe-based materials can be controlled to become excellent thermoelectrics for power generation via the successful application of several key concepts that obviate the well-known disadvantages of SnTe. First, we show that Sn self-compensation can effectively reduce the Sn vacancies and decrease the hole carrier density. For example, a 3 mol % self-compensation of Sn results in a 50% improvement in the figure of merit ZT. In addition, we reveal that Cd, nominally isoelectronic with Sn, favorably impacts the electronic band structure by (a) diminishing the energy separation between the light-hole and heavy-hole valence bands in the material, leading to an enhanced Seebeck coefficient, and (b) enlarging the energy band gap. Thus, alloying with Cd atoms enables a form of valence band engineering that improves the high-temperature thermoelectric performance, where p-type samples of SnCd(0.03)Te exhibit ZT values of ~0.96 at 823 K, a 60% improvement over the Cd-free sample. Finally, we introduce endotaxial CdS or ZnS nanoscale precipitates that reduce the lattice thermal conductivity of SnCd(0.03)Te with no effect on the power factor. We report that SnCd(0.03)Te that are endotaxially nanostructured with CdS and ZnS have a maximum ZTs of ~1.3 and ~1.1 at 873 K, respectively. Therefore, SnTe-based materials could be ideal alternatives for p-type lead chalcogenides for high temperature thermoelectric power generation.

  1. High thermoelectric performance of p-type SnTe via a synergistic band engineering and nanostructuring approach.

    PubMed

    Tan, Gangjian; Zhao, Li-Dong; Shi, Fengyuan; Doak, Jeff W; Lo, Shih-Han; Sun, Hui; Wolverton, Chris; Dravid, Vinayak P; Uher, Ctirad; Kanatzidis, Mercouri G

    2014-05-14

    SnTe is a potentially attractive thermoelectric because it is the lead-free rock-salt analogue of PbTe. However, SnTe is a poor thermoelectric material because of its high hole concentration arising from inherent Sn vacancies in the lattice and its very high electrical and thermal conductivity. In this study, we demonstrate that SnTe-based materials can be controlled to become excellent thermoelectrics for power generation via the successful application of several key concepts that obviate the well-known disadvantages of SnTe. First, we show that Sn self-compensation can effectively reduce the Sn vacancies and decrease the hole carrier density. For example, a 3 mol % self-compensation of Sn results in a 50% improvement in the figure of merit ZT. In addition, we reveal that Cd, nominally isoelectronic with Sn, favorably impacts the electronic band structure by (a) diminishing the energy separation between the light-hole and heavy-hole valence bands in the material, leading to an enhanced Seebeck coefficient, and (b) enlarging the energy band gap. Thus, alloying with Cd atoms enables a form of valence band engineering that improves the high-temperature thermoelectric performance, where p-type samples of SnCd(0.03)Te exhibit ZT values of ~0.96 at 823 K, a 60% improvement over the Cd-free sample. Finally, we introduce endotaxial CdS or ZnS nanoscale precipitates that reduce the lattice thermal conductivity of SnCd(0.03)Te with no effect on the power factor. We report that SnCd(0.03)Te that are endotaxially nanostructured with CdS and ZnS have a maximum ZTs of ~1.3 and ~1.1 at 873 K, respectively. Therefore, SnTe-based materials could be ideal alternatives for p-type lead chalcogenides for high temperature thermoelectric power generation. PMID:24785377

  2. Zinc and sulfur isotope variation in sphalerite from carbonate-hosted zinc deposits, Cantabria, Spain

    NASA Astrophysics Data System (ADS)

    Pašava, Jan; Tornos, Fernando; Chrastný, Vladislav

    2014-10-01

    We studied zinc and sulfur isotopes and the chemical composition of sphalerite samples from Picos de Europa (Aliva mine) and sphalerite and hydrozincite samples from La Florida mine, two carbonate-hosted Mississippi Valley-type (MVT) deposits located in northern Spain; despite being close, they are hosted in carbonatic rocks of different ages, Lower Carboniferous and Lower Cretaceous, respectively. The two generations of sphalerite at Picos de Europa show different δ66Zn values (stage 1 sphalerite +0.24 per mil and stage 2 sphalerite from -0.75 to +0.08 per mil). Both generations also differ in the sulfur isotope composition (stage 1 has δ34S = +6.6 and stage 2 has δ34S = -0.9 to +2.9 per mil) and the chemical composition (stage 1 sphalerite, compared to stage 2 sphalerite, is significantly enriched in Pb, As, Mn, Sb, slightly enriched in Ag, Ni, and Cu and depleted in Co, Ga, Tl, Te, Ge, and Sn). We suggest that Zn isotope fractionation was controlled predominantly by pH and T changes. High Zn isotope values reflect rapid precipitation of sphalerite from higher-temperature acidic fluids that carried Zn mostly as chloride species after interaction with carbonate rocks while lower Zn isotope values most likely resulted from a longer precipitation process from fluid at higher pH and decreasing T that carried dominantly Zn sulfide species. At La Florida, sphalerite samples show light 66Zn-depleted signatures with δ66Zn values from -0.80 to -0.01 per mil (mostly between -0.80 and -0.24 per mil) and δ34S values from +10.7 to +15.7 per mil without any relationship between the δ66Zn and δ34S values. Here, the variation in Zn isotope values is interpreted as related to mixing of fluids from two reservoirs. The Zn was carried by a single deep-seated and higher T (~250-320 °C) fluid, and precipitation took place after mixing with a connate S-rich fluid in a system with mH2S > mZn2+ as a result of change in pH, T, and Zn predominant species. The light δ66Zn

  3. SN~2012cg: Evidence for Interaction Between a Normal Type Ia Supernova and a Non-degenerate Binary Companion

    NASA Astrophysics Data System (ADS)

    Marion, G. H.; Brown, Peter J.; Vinkó, Jozsef; Silverman, Jeffrey M.; Sand, David J.; Challis, Peter; Kirshner, Robert P.; Wheeler, J. Craig; Berlind, Perry; Brown, Warren R.; Calkins, Michael L.; Camacho, Yssavo; Dhungana, Govinda; Foley, Ryan J.; Friedman, Andrew S.; Graham, Melissa L.; Howell, D. Andrew; Hsiao, Eric Y.; Irwin, Jonathan M.; Jha, Saurabh W.; Kehoe, Robert; Macri, Lucas M.; Maeda, Keiichi; Mandel, Kaisey; McCully, Curtis; Pandya, Viraj; Rines, Kenneth J.; Wilhelmy, Steven; Zheng, Weikang

    2016-04-01

    We report evidence for excess blue light from the Type Ia supernova (Sn Ia) SN 2012cg at 15 and 16 days before maximum B-band brightness. The emission is consistent with predictions for the impact of the supernova on a non-degenerate binary companion. This is the first evidence for emission from a companion to a normal SN Ia. Sixteen days before maximum light, the B-V color of SN 2012cg is 0.2 mag bluer than for other normal SN Ia. At later times, this supernova has a typical SN Ia light curve, with extinction-corrected {M}B=-19.62+/- 0.02 mag and {{Δ }}{m}15(B)=0.86+/- 0.02. Our data set is extensive, with photometry in seven filters from five independent sources. Early spectra also show the effects of blue light, and high-velocity features are observed at early times. Near maximum, the spectra are normal with a silicon velocity vSi = -10,500 km s-1. Comparing the early data with models by Kasen favors a main-sequence companion of about six solar masses. It is possible that many other SN Ia have main-sequence companions that have eluded detection because the emission from the impact is fleeting and faint.

  4. Laser Isotope Enrichment for Medical and Industrial Applications

    SciTech Connect

    Leonard Bond

    2006-07-01

    Laser Isotope Enrichment for Medical and Industrial Applications by Jeff Eerkens (University of Missouri), Jay Kunze (Idaho State University), and Leonard Bond (Idaho National Laboratory) The principal isotope enrichment business in the world is the enrichment of uranium for commercial power reactor fuels. However, there are a number of other needs for separated isotopes. Some examples are: 1) Pure isotopic targets for irradiation to produce medical radioisotopes. 2) Pure isotopes for semiconductors. 3) Low neutron capture isotopes for various uses in nuclear reactors. 4) Isotopes for industrial tracer/identification applications. Examples of interest to medicine are targets to produce radio-isotopes such as S-33, Mo-98, Mo-100, W-186, Sn-112; while for MRI diagnostics, the non-radioactive Xe-129 isotope is wanted. For super-semiconductor applications some desired industrial isotopes are Si-28, Ga-69, Ge-74, Se-80, Te-128, etc. An example of a low cross section isotope for use in reactors is Zn-68 as a corrosion inhibitor material in nuclear reactor primary systems. Neutron activation of Ar isotopes is of interest in industrial tracer and diagnostic applications (e.g. oil-logging). . In the past few years there has been a sufficient supply of isotopes in common demand, because of huge Russian stockpiles produced with old electromagnetic and centrifuge separators previously used for uranium enrichment. Production of specialized isotopes in the USA has been largely accomplished using old ”calutrons” (electromagnetic separators) at Oak Ridge National Laboratory. These methods of separating isotopes are rather energy inefficient. Use of lasers for isotope separation has been considered for many decades. None of the proposed methods have attained sufficient proof of principal status to be economically attractive to pursue commercially. Some of the authors have succeeded in separating sulfur isotopes using a rather new and different method, known as condensation

  5. SN2001IG: Detecting a Mass Loss Phase?

    NASA Astrophysics Data System (ADS)

    Schlegel, Eric

    2001-09-01

    The X-ray emission of supernovae is a young field with relatively little data. X-rays provide information about the circumstellar ejecta as the outgoing shock runs into matter from previous phases of mass loss. A reverse shock is created which generates low-energy X-rays (~1 keV) while the outgoing shock generates harder events. The X-rays probe the circumstellar matter and are expected to provide measures of abundances in spectral lines. The X-ray light curve (LC) additionally provides a measure of the matter distribution (Ref for SN: Schlegel 1995, Reports on Prog in Physics, 58, 1375). The radio LC of SN1979C has been interpreted as revealing waves of mass loss (Weiler et al. 1992, ApJ, 399, 672) from the progenitor. No other SN has shown such behavior prior to the recent increase in the radio LC of SN2001ig. We expect the hard and soft X-rays to behave differently, directly testing shock/reverse shock theory.

  6. SrZn2Sn2 and Ca2Zn3Sn6 — two new Ae-Zn-Sn polar intermetallic compounds (Ae: alkaline earth metal)

    NASA Astrophysics Data System (ADS)

    Stegmaier, Saskia; Fässler, Thomas F.

    2012-08-01

    SrZn2Sn2 and Ca2Zn3Sn6, two closely related new polar intermetallic compounds, were obtained by high temperature reactions of the elements. Their crystal structures were determined with single crystal XRD methods, and their electronic structures were analyzed by means of DFT calculations. The Zn-Sn structure part of SrZn2Sn2 comprises (anti-)PbO-like {ZnSn4/4} and {SnZn4/4} layers. Ca2Zn3Sn6 shows similar {ZnSn4/4} layers and {Sn4Zn} slabs constructed of a covalently bonded Sn scaffold capped by Zn atoms. For both phases, the two types of layers are alternatingly stacked and interconnected via Zn-Sn bonds. SrZn2Sn2 adopts the SrPd2Bi2 structure type, and Ca2Zn3Sn6 is isotypic to the R2Zn3Ge6 compounds (R=La, Ce, Pr, Nd). Band structure calculations indicate that both SrZn2Sn2 and Ca2Zn3Sn6 are metallic. Analyses of the chemical bonding with the electron localization function (ELF) show lone pair like basins at Sn atoms and Zn-Sn bonding interactions between the layers for both title phases, and covalent Sn-Sn bonding within the {Sn4Zn} layers of Ca2Zn3Sn6.

  7. SAO RAS SN candidates classifications

    NASA Astrophysics Data System (ADS)

    Fatkhullin, T. A.; Moskvitin, A. S.

    2016-08-01

    We observed SN candidates (AT 2016eow, AT 2016enu and AT 2016enf) with the BTA/Scorpio-I on August, 4. Direct images in the R band and long-slit spectra in the range of 3600-7600AA (resolution FWHM = 10A) were obtained.

  8. Geochemistry of tin (Sn) in Chinese coals.

    PubMed

    Qu, Qinyuan; Liu, Guijian; Sun, Ruoyu; Kang, Yu

    2016-02-01

    Based on 1625 data collected from the published literature, the geochemistry of tin (Sn) in Chinese coals, including the abundance, distribution, modes of occurrence, genetic types and combustion behavior, was discussed to make a better understanding. Our statistic showed the average Sn of Chinese coal was 3.38 mg/kg, almost two times higher than the world. Among all the samples collected, Guangxi coals occupied an extremely high Sn enrichment (10.46 mg/kg), making sharp contrast to Xinjiang coals (0.49 mg/kg). Two modes of occurrence of Sn in Chinese coals were found, including sulfide-bounded Sn and clay-bounded Sn. In some coalfields, such as Liupanshui, Huayingshan and Haerwusu, a response between REEs distribution and Sn content was found which may caused by the transportation of Sn including clay minerals between coal seams. According to the responses reflecting on REEs patterns of each coalfield, several genetic types of Sn in coalfields were discussed. The enrichment of Sn in Guangxi coals probably caused by Sn-rich source rocks and multiple-stage hydrothermal fluids. The enriched Sn in western Guizhou coals was probably caused by volcanic ashes and sulfide-fixing mechanism. The depletion of Sn in Shengli coalfield, Inner Mongolia, may attribute to hardly terrigenous input and fluids erosion. As a relative easily volatilized element, the Sn-containing combustion by-products tended to be absorbed on the fine particles of fly ash. In 2012, the emission flux of Sn by Chinese coal combustion was estimated to be 0.90 × 10(9) g. PMID:25686909

  9. LED Die-Bonded on the Ag/Cu Substrate by a Sn-BiZn-Sn Bonding System

    NASA Astrophysics Data System (ADS)

    Tang, Y. K.; Hsu, Y. C.; Lin, E. J.; Hu, Y. J.; Liu, C. Y.

    2016-08-01

    In this study, light emitting diode (LED) chips were die-bonded on a Ag/Cu substrate by a Sn-BixZn-Sn bonding system. A high die-bonding strength is successfully achieved by using a Sn-BixZn-Sn ternary system. At the bonding interface, there is observed a Bi-segregation phenomenon. This Bi-segregation phenomenon solves the problems of the brittle layer-type Bi at the joint interface. Our shear test results show that the bonding interface with Bi-segregation enhances the shear strength of the LED die-bonding joints. The Bi-0.3Zn and Bi-0.5Zn die-bonding cases have the best shear strength among all die-bonding systems. In addition, we investigate the atomic depth profile of the deposited Bi-xZn layer by evaporating Bi-xZn E-gun alloy sources. The initial Zn content of the deposited Bi-Zn alloy layers are much higher than the average Zn content in the deposited Bi-Zn layers.

  10. Radio Observations of SN 2006fo

    NASA Astrophysics Data System (ADS)

    Soderberg, Alicia

    2006-09-01

    "I observed the Type Ibc SN 2006fo (IAUC 8750, CBET 643) with the Very Large Array on Sep 26.2 UT as part of an ongoing program to study the radio properties of SNe Ibc discovered through the SDSS SN survey. SN 2006fo is not detected at 8.5 or 22.5 GHz. At a distance of 88 Mpc, the radio luminosity of SN 2006fo is at least a factor of 100 lower than that of SN 1998bw at a similar epoch (Kulkarni et al., 1998, Nature, 395, 663).

  11. The influence of hydrogen contamination on the structural stability of CoSn under compression.

    PubMed

    Mikhaylushkin, A S

    2010-11-01

    The binary CoSn compound has a unique ground state large-void crystal structure, whose stability under pressure has recently been examined. Whereas theoretical results predicted a series of phase transformations, the room temperature experiments did not observe any structural change. We suggest that the large void of a CoSn-type structure could contain natural impurities such as hydrogen, which can influence the thermodynamic stability of a CoSn system and explain the unusual disagreement between the theoretical and experimental results. Based on first-principles calculations we reveal that the contamination of CoSn by hydrogen only results in a subtle change of structural parameters and the equation of state of CoSn, but drastically increases the stability of the CoSn-type phase in comparison with the high-pressure phases predicted earlier. We argue that the hardly detectable natural impurities of light elements in porous compounds like CoSn are able to change the phase equilibria. PMID:21403329

  12. Neutron emission following muon capture in Ce-142, Ce-140, Ba-138, and Sn-120.

    NASA Technical Reports Server (NTRS)

    Lucas, G. R., Jr.; Martin, P.; Welsh, R. E.; Jenkins, D. A.; Powers, R. J.; Kunselman, A. R.; Miller, G. H.

    1973-01-01

    Branching ratios to excited nuclear states formed after muon capture have been measured with Ge(Li) detectors. The delayed gamma rays were observed in studies of muonic Ce-142, Ce-140, Ba-138, and Sn-120, using separated isotopes. The resulting isotopes formed indicate at least a 60% probability of neutron emission upon muon capture, with the most likely product resulting from single-neutron emission. No evidence for delayed proton emission with a probability higher than 2% was found. Using our more precise energies for the observed nuclear transitions, we present revised energy levels schemes for La-141, La-139, Cs-137, and In-119.

  13. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1977-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, in the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  14. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C.P.; Rockwood, S.D.; Jensen, R.J.; Lyman, J.L.; Aldridge, J.P. III.

    1987-04-07

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO[sub 2] laser light may be used to highly enrich [sup 34]S in natural SF[sub 6] and [sup 11]B in natural BCl[sub 3]. 8 figs.

  15. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1987-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  16. Preparation and photocatalytic properties of AgI–SnO{sub 2} nano-composites

    SciTech Connect

    Wen, Biao; Wang, Xiao-Hui; Lu, Juan; Cao, Jia-Lei; Wang, Zuo-Shan

    2013-05-15

    Highlights: ► AgI–SnO{sub 2} nano-composites have been successfully synthesized. ► As-prepared AgI–SnO{sub 2} nano-composites own the excellent visible light photocatalytic activity. ► As-prepared AgI–SnO{sub 2} nano-composites own the excellent stability. - Abstract: AgI doped SnO{sub 2} nano-composites were prepared by the chemical coprecipitation method and were characterized by the X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Results showed that main of the I{sup −} ions remained in the AgI lattice which is highly dispersed in the system. The photo-catalytic experiments performed under visible light irradiation using methylene blue as the pollutant revealed that not only the photo-catalytic activity but also the stability of SnO{sub 2} based photocatalyst could be improved by introduction of an appropriate amount of AgI, and the result was further supported by the UV–Vis diffuse reflection spectra and the electron spin-resonance spectra. Among all of the samples, AgI–SnO{sub 2} nano-composite with 2At% AgI exhibited the best catalytic efficiency and stability.

  17. SN 1961V: From Alpha to Omega?

    NASA Astrophysics Data System (ADS)

    Van Dyk, Schuyler D.; Filippenko, Alexei V.; Cenko, Bradley S.; Shields, Joseph C.

    2013-06-01

    The extraordinary object SN 1961V in NGC 1058 remains controversial to this day. It has long been considered the prototypical "supernova impostor," i.e., the giant eruption of a highly massive star with energetics that rival true supernovae. However, a number of arguments have been put forward that SN 1961V actually was a true SN, and that the explosion followed a sustained powerful outburst from its precursor star, much like the amazing SN 2009ip and other recent events. We will briefly discuss the debate that has roiled over SN 1961V, and we will also present evidence, including from new observations, which may indicate that the precursor has survived. Determining the true nature of SN 1961V will inform our understanding of the late stages of pre-SN evolution for the most massive stars.

  18. Atomic line emission analyzer for hydrogen isotopes

    DOEpatents

    Kronberg, J.W.

    1993-03-30

    Apparatus for isotopic analysis of hydrogen comprises a low pressure chamber into which a sample of hydrogen is introduced and then exposed to an electrical discharge to excite the electrons of the hydrogen atoms to higher energy states and thereby cause the emission of light on the return to lower energy states, a Fresnel prism made at least in part of a material anomalously dispersive to the wavelengths of interest for dispersing the emitted light, and a photodiode array for receiving the dispersed light. The light emitted by the sample is filtered to pass only the desired wavelengths, such as one of the lines of the Balmer series for hydrogen, the wavelengths of which differ slightly from one isotope to another. The output of the photodiode array is processed to determine the relative amounts of each isotope present in the sample. Additionally, the sample itself may be recovered using a metal hydride.

  19. Atomic line emission analyzer for hydrogen isotopes

    DOEpatents

    Kronberg, James W.

    1993-01-01

    Apparatus for isotopic analysis of hydrogen comprises a low pressure chamber into which a sample of hydrogen is introduced and then exposed to an electrical discharge to excite the electrons of the hydrogen atoms to higher energy states and thereby cause the emission of light on the return to lower energy states, a Fresnel prism made at least in part of a material anomalously dispersive to the wavelengths of interest for dispersing the emitted light, and a photodiode array for receiving the dispersed light. The light emitted by the sample is filtered to pass only the desired wavelengths, such as one of the lines of the Balmer series for hydrogen, the wavelengths of which differ slightly from one isotope to another. The output of the photodiode array is processed to determine the relative amounts of each isotope present in the sample. Additionally, the sample itself may be recovered using a metal hydride.

  20. Atomic line emission analyzer for hydrogen isotopes

    DOEpatents

    Kronberg, J.W.

    1991-05-08

    Apparatus for isotopic analysis of hydrogen comprises a low pressure chamber into which a sample of hydrogen is introduced and then exposed to an electrical discharge to excite the electrons of the hydrogen atoms to higher energy states and thereby cause the emission of light on the return to lower energy states, a Fresnel prism made at least in part of a material anomalously dispersive to the wavelengths of interest for dispersing the emitted light, and a photodiode array for receiving the dispersed light. The light emitted by the sample is filtered to pass only the desired wavelengths, such as one of the lines of the Balmer series for hydrogen, the wavelengths of which differ slightly from one isotope to another. The output of the photodiode array is processed to determine the relative amounts of each isotope present in the sample. Additionally, the sample itself may be recovered using, a metal hydride.

  1. Compound-Specific Carbon, Nitrogen, and Hydrogen Isotopic Ratios for Amino Acids in CM and CR Chondrites and their use in Evaluating Potential Formation Pathways

    NASA Technical Reports Server (NTRS)

    Elsila, Jamie E.; Charnley, Steven B.; Burton, Aaron S.; Glavin, Daniel P.; Dworkin, Jason P.

    2012-01-01

    Stable hydrogen, carbon, and nitrogen isotopic ratios (oD, 013C, and olSN) of organic compounds can revcal information about their origin and formation pathways. Several formation mechanisms and environments have been postulated for the amino acids detected in carbonaceous chondrites. As each proposed mechanism utilizes different precursor molecules, the isotopic signatures of the resulting amino acids may indicate the most likely of these pathways. We have applied gas chromatography with mass spectrometry and combustion isotope ratio mass spectrometry to measure the compound-specific C, N, and H stable isotopic ratios of amino acids from seven CM and CR carbonaceous chondrites: CM1I2 Allan Hills (ALH) 83100, CM2 Murchison, CM2 Lewis Cliff (LEW) 90500, CM2 Lonewolf Nunataks (LON) 94101, CRZ Graves Nunataks (GRA) 95229, CRZ Elephant Moraine (EET) 92042, and CR3 Queen Alexandra Range (QUE) 99177. We compare the isotopic compositions of amino acids in these meteorites with predictions of expected isotopic enrichments from potential formation pathways. We observe trends of decreasing ODC and increasing oD with increasing carbon number in the aH, (l-NH2 amino acids that correspond to predictions made for formation via Streckercyanohydrin synthesis. We also observe light ODC signatures for -alanine, which may indicate either formation via Michael addition or via a pathway that forms primarily small, straight-chain, amine-terminal amino acids (n-ro-amino acids). Higher deuterium enrichments are observed in amethyl amino acids, indicating formation of these amino acids or their precursors in cold interstellar or nebular environments. Finally, individual amino acids are more enriched in deuterium in CR chondrites than CM chondrites, reflecting different parent-body chemistry.

  2. Is There Evidence for a Hubble Bubble? The Nature of SN Ia Colors And Dust in External Galaxies

    SciTech Connect

    Conley, A.; Carlberg, R.G.; Guy, J.; Howell, D.A.; Jha, S.; Riess, A.G.; Sullivan, M.; /Toronto U., Astron. Dept.

    2007-06-06

    We examine recent evidence from the luminosity-redshift relation of Type Ia Supernovae for the {approx} 3 {sigma} detection of a ''Hubble bubble'' -- a departure of the local value of the Hubble constant from its globally averaged value. By comparing the MLCS2k2 fits used in that study to the results from other light-curve fitters applied to the same data, we demonstrate that this is related to the interpretation of SN color excesses (after correction for a light-curve shape-color relation) and the presence of a color gradient across the local sample. If the slope of the linear relation ({beta}) between SN color excess and luminosity is fit empirically, then the bubble disappears. If, on the other hand, the color excess arises purely from Milky-Way like dust, then SN data clearly favors a Hubble bubble. We demonstrate that SN data give {beta} {approx} 2, instead of the {beta} {approx} 4 one would expect from purely Milky-Way-like dust. This suggests that either SN intrinsic colors are more complicated than can be described with a single light-curve shape parameter, or that dust around SN is unusual. Disentangling these possibilities is both a challenge and an opportunity for large-survey SN Ia cosmology.

  3. Orbital Dependent Nucleonic Pairing in the Lightest Known Isotopes of Tin

    SciTech Connect

    Darby, Iain; Grzywacz, R.; Batchelder, J. C.; Bingham, C. R.; Cartegni, L.; Gross, Carl J; Liddick, Sean; Nazarewicz, Witold; Padgett, Stephen; Papenbrock, T.; Rajabali, M. M.; Rotureau, J.; Rykaczewski, Krzysztof Piotr

    2010-01-01

    By studying the {sup 109}Xe {yields} {sup 105}Te {yields} {sup 101}Sn superallowed {alpha}-decay chain, we observe low-lying states in {sup 101}Sn, the one-neutron system outside doubly magic {sup 100}Sn. We find that the spins of the ground state (J=7/2) and first excited state (J=5/2) in {sup 101}Sn are reversed with respect to the traditional level ordering postulated for {sup 103}Sn and the heavier tin isotopes. Through simple arguments and state-of-the-art shell-model calculations we explain this unexpected switch in terms of a transition from the single-particle regime to the collective mode in which orbital-dependent pairing correlations dominate.

  4. Electrical and optical properties of SnS2/WSe2 van der Waals Heterojunction FETs

    NASA Astrophysics Data System (ADS)

    Zubair, Ahmad; Nourbakhsh, Amirhasan; Dresselhaus, Mildred; Palacios, Tomas

    Two dimensional crystals based on atomically thin films of transition metal dichalcogenides offer an exciting platform for various optoelectronic applications. Their unique crystal properties make them particularly attractive for van der Waals heterostructures which open up an additional degree of freedom to tailor the material properties into new physics and device applications. In this work, we explore, for the first time, the optoelectronic properties of van der Waals SnS2/WSe2 heterojunction. WSe2 is an ambipolar semiconductor while SnS2 is an n-type wide bandgap semiconductor. We use the pickup and dry transfer methods to fabricate SnS2/WSe2 heterojunction transistors (hetero-FETs). We observe negative differential transconductance in the SnS2/WSe2 hetero-FET. Also, the heterostructure couples strongly to incident light and shows high photovoltaic responsivity which can find applications in nano-devices such as photo-detectors and solar cells.

  5. Development of Nb{sub 3}Sn Cavity Vapor Diffusion Deposition System

    SciTech Connect

    Eremeev, Grigory V.; Macha, Kurt M.; Clemens, William A.; Park, HyeKyoung; Williams, R. Scott

    2014-02-01

    Nb{sub 3}Sn is a BCS superconductors with the superconducting critical temperature higher than that of niobium, so theoretically it surpasses the limitations of niobium in RF fields. The feasibility of technology has been demonstrated at 1.5 GHz with Nb{sub 3}Sn vapor deposition technique at Wuppertal University. The benefit at these frequencies is more pronounced at 4.2 K, where Nb{sub 3}Sn coated cavities show RF resistances an order of magnitude lower than that of niobium. At Jefferson Lab we started the development of Nb{sub 3}Sn vapor diffusion deposition system within an R\\&D development program towards compact light sources. Here we present the current progress of the system development.

  6. Multifunctional Sn- and Fe-Codoped In2O3 Colloidal Nanocrystals: Plasmonics and Magnetism.

    PubMed

    Tandon, Bharat; Shanker, G Shiva; Nag, Angshuman

    2014-07-01

    We prepared Fe- and Sn-codoped colloidal In2O3 nanocrystals (∼6 nm). Sn doping provides free electrons in the conduction band, originating localized surface plasmon resonance (LSPR) and electrical conductivity. The LSPR band can be tuned between 2000 and >3000 nm, depending on the extent and kind of dopant ions. Fe doping, on the other hand, provides unpaired electrons, resulting in weak ferromagnetism at room temperature. Fe doping shifts the LSPR band of 10% Sn-doped In2O3 nanocrystals to a longer wavelength along with a reduction in intensity, suggesting trapping of charge carriers around the dopant centers, whereas Sn doping increases the magnetization of 10% Fe-doped In2O3 nanocrystals, probably because of the free electron mediated interactions between distant magnetic ions. The combination of plasmonics and magnetism, in addition to electronic conductivity and visible-light transparency, is a unique feature of our colloidal codoped nanocrystals.

  7. On the RMgSn rare earth compounds

    SciTech Connect

    Manfrinetti, P.; Provino, A.; Gschneidner, K. A.

    2009-04-07

    A new family of ternary rare earth compounds, RMgSn, has been synthesized and their crystal structures, formation thermodynamics and melting behavior have been studied. All of the rare earth elements (including Y) form the 1:1:1 equiatomic phase with Mg and Sn. These compounds crystallize with two different structure types: the RMgSn phases with the light R (R = La, Ce and Pr) adopt the orthorhombic TiNiSi structure type (an ordered derivative of the Co{sub 2}Si-type structure, oP12, space group Pnma), while the ones formed by the heavier R (R = Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm and Lu, plus Y) have the tetragonal CeScSi-type structure (an ordered derivative of the La{sub 2}Sb-type structure, t/12, space group/4/mmm). The observed unit cell volume V{sub obs} and the mean atomic volume V{sub obs}/n (where n is the number of atoms in a unit cell) both decrease as expected due to the lanthanide contraction, but following different trends. The volume of formation ({Delta}V%) becomes more negative on going from La to Lu along the series. All phases have been found to form congruently (including YMgSn and probably LuMgSn). Their melting temperatures decrease from La to Lu, but with different slopes for the two different structure types. Relationships, between the volume of formation and also the melting points with the lanthanide contraction have been examined. The relationship between the former is anomalous compared to that observed for other R{sub x}M{sub y} series of compounds, while the latter relationship is consistent with previously published results.

  8. Carbon dots decorated vertical SnS2 nanosheets for efficient photocatalytic oxygen evolution

    NASA Astrophysics Data System (ADS)

    Cheng, Zhongzhou; Wang, Fengmei; Shifa, Tofik Ahmed; Liu, Kaili; Huang, Yun; Liu, Quanlin; Jiang, Chao; He, Jun

    2016-08-01

    Metal sulfides are highly desirable materials for photocatalytic water splitting because of their appropriate energy bands. However, the poor stability under light illumination in water hinders their wide applications. Here, two-dimensional SnS2 nanosheets, along with carbon dots of the size around 10 nm, are uniformly grown on fluorine doped tin oxide glasses with a layer of nickel nanoparticles. Significantly, strong light absorption and enhanced photocurrent density are achieved after integration of SnS2 nanosheets with carbon dots. Notably, the rate of oxygen evolution reached up to 1.1 mmol g-1 h-1 under simulated sunlight irradiation featuring a good stability.

  9. Isotopic evidence of unaccounted for Fe and Cu erythropoietic pathways.

    PubMed

    Albarède, Francis; Telouk, Philippe; Lamboux, Aline; Jaouen, Klervia; Balter, Vincent

    2011-09-01

    Despite its potential importance for understanding perturbations in the Fe-Cu homeostatic pathways, the natural isotopic variability of these metals in the human body remains unexplored. We measured the Fe, Cu, and Zn isotope compositions of total blood, serum, and red blood cells of ~50 young blood donors by multiple-collector ICP-MS after separation and purification by anion exchange chromatography. Zinc shows much less overall isotopic variability than Fe and Cu, which indicates that isotope fractionation depends more on redox conditions than on ligand coordination. On average, Fe in erythrocytes is isotopically light with respect to serum, whereas Cu is heavy. Iron and Cu isotope compositions clearly separate erythrocytes of men and women. Fe and Cu from B-type men erythrocytes are visibly more fractionated than all the other blood types. Isotope compositions provide an original method for evaluating metal mass balance and homeostasis. Natural isotope variability shows that the current models of Fe and Cu erythropoiesis violate mass balance requirements. It unveils unsuspected major pathways for Fe, with erythropoietic production of isotopically heavy ferritin and hemosiderin, and for Cu, with isotopically light Cu being largely channeled into blood and lymphatic circulation rather than into superoxide dismutase-laden erythrocytes. Iron isotopes provide an intrinsic measuring rod of the erythropoietic yield, while Cu isotopes seem to gauge the relative activity of erythropoiesis and lymphatics.

  10. Constraining the progenitor of the Type Ia Supernova SN 2012cg

    NASA Astrophysics Data System (ADS)

    Liu, Zheng-Wei; Stancliffe, Richard J.

    2016-06-01

    The nature of the progenitors of Type Ia supernovae (SNe Ia) is not yet fully understood. In the single-degenerate (SD) scenario, the collision of the SN ejecta with its companion star is expected to produce detectable ultraviolet emission in the first few days after the SN explosion within certain viewing angles. It was recently found that the B - V colour of the nearby SN Ia SN 2012cg at about 16 d before the maximum B-band brightness was about 0.2 mag bluer than those of other normal SNe Ia, which was reported as the first evidence for excess blue light from the interaction of normal SN Ia ejecta with its companion star. In this work, we compare current observations for SN 2012cg from its pre-explosion phase to the late-time nebular phase with theoretical predictions from binary evolution and population synthesis calculations for a variety of popular progenitor scenarios. We find that a main-sequence donor or a carbon-oxygen white dwarf donor binary system is more likely to be the progenitor of SN 2012cg. However, both scenarios also predict properties which are in contradiction to the observed features of this system. Taking both theoretical and observational uncertainties into account, we suggest that it might be too early to conclude that SN 2012cg was produced from an explosion of a Chandrasekhar-mass white dwarf in the SD scenario. Future observations and improved detailed theoretical modelling are still required to place a more stringent constraint on the progenitor of SN 2012cg.

  11. SN 2012au: A GOLDEN LINK BETWEEN SUPERLUMINOUS SUPERNOVAE AND THEIR LOWER-LUMINOSITY COUNTERPARTS

    SciTech Connect

    Milisavljevic, Dan; Soderberg, Alicia M.; Margutti, Raffaella; Drout, Maria R.; Marion, G. Howie; Sanders, Nathan E.; Lunnan, Ragnhild; Chornock, Ryan; Berger, Edo; Foley, Ryan J.; Challis, Pete; Kirshner, Robert P.; Dittmann, Jason; Bieryla, Allyson; Kamble, Atish; Chakraborti, Sayan; Hsiao, Eric Y.; Fesen, Robert A.; Parrent, Jerod T.; Levesque, Emily M.; and others

    2013-06-20

    We present optical and near-infrared observations of SN 2012au, a slow-evolving supernova (SN) with properties that suggest a link between subsets of energetic and H-poor SNe and superluminous SNe. SN 2012au exhibited conspicuous Type-Ib-like He I lines and other absorption features at velocities reaching Almost-Equal-To 2 Multiplication-Sign 10{sup 4} km s{sup -1} in its early spectra, and a broad light curve that peaked at M{sub B} = -18.1 mag. Models of these data indicate a large explosion kinetic energy of {approx}10{sup 52} erg and {sup 56}Ni mass ejection of M{sub Ni} Almost-Equal-To 0.3 M{sub Sun} on par with SN 1998bw. SN 2012au's spectra almost one year after explosion show a blend of persistent Fe II P-Cyg absorptions and nebular emissions originating from two distinct velocity regions. These late-time emissions include strong [Fe II], [Ca II], [O I], Mg I], and Na I lines at velocities {approx}> 4500 km s{sup -1}, as well as O I and Mg I lines at noticeably smaller velocities {approx}< 2000 km s{sup -1}. Many of the late-time properties of SN 2012au are similar to the slow-evolving hypernovae SN 1997dq and SN 1997ef, and the superluminous SN 2007bi. Our observations suggest that a single explosion mechanism may unify all of these events that span -21 {approx}< M{sub B} {approx}< -17 mag. The aspherical and possibly jetted explosion was most likely initiated by the core collapse of a massive progenitor star and created substantial high-density, low-velocity Ni-rich material.

  12. THE 2012 RISE OF THE REMARKABLE TYPE IIn SN 2009ip

    SciTech Connect

    Prieto, Jose L.; Brimacombe, J.; Drake, A. J.; Howerton, S.

    2013-02-01

    Recent observations by Mauerhan et al. have shown the unprecedented transition of the previously identified luminous blue variable (LBV) and supernova (SN) impostor SN 2009ip to a real Type IIn SN explosion. We present {approx}100 optical R- and I-band photometric measurements of SN 2009ip obtained between UT 2012 September 23.6 and October 9.6, using 0.3-0.4 m aperture telescopes from the Coral Towers Observatory in Cairns, Australia. The light curves show well-defined phases, including very rapid brightening early on (0.5 mag in 6 hr observed during the night of September 24), a transition to a much slower rise between September 25 and September 28, and a plateau/peak around October 7. These changes are coincident with the reported spectroscopic changes that most likely mark the start of a strong interaction between the fast SN ejecta and a dense circumstellar medium formed during the LBV eruptions observed in recent years. In the 16-day observing period, SN 2009ip brightened by 3.7 mag from I = 17.4 mag on September 23.6 (M{sub I} {approx_equal} -14.2) to I = 13.7 mag (M{sub I} {approx_equal} -17.9) on October 9.6, radiating {approx}3 Multiplication-Sign 10{sup 49} erg in the optical wavelength range. As of 2012 October 9.6, SN 2009ip is more luminous than most Type IIP SN and comparable to other Type IIn SN.

  13. A novel methodology to investigate isotopic biosignatures

    NASA Astrophysics Data System (ADS)

    Horner, T. J.; Lee, R. B. Y.; Henderson, G. M.; Rickaby, R. E. M.

    2012-04-01

    An enduring goal of trace metal isotopic studies of Earth History is to find isotopic 'fingerprints' of life or of life's individual physiochemical processes. Generally, such signatures are sought by relating an isotopic effect observed in controlled laboratory conditions or a well-characterized environment to a more complex system or the geological record. However, such an approach is ultimately limited because life exerts numerous isotopic fractionations on any one element so it is hard to dissect the resultant net fractionation into its individual components. Further, different organisms, often with the same apparent cellular function, can express different isotopic fractionation factors. We have used a novel method to investigate the isotopic fractionation associated with a single physiological process-enzyme specific isotopic fractionation. We selected Cd isotopes since only one biological use of Cd is known, CdCA (a Cd/Zn carbonic anhydrase from the coastal diatom T. Weissflogii). Thus, our investigation can also inform the long standing mystery as to why this generally toxic element appears to have a nutrient-like dissolved isotopic and concentration profile in the oceans. We used the pET-15b plasmid to insert the CdCA gene into the E. coli genome. There is no known biochemical function for Cd in E. coli, making it an ideal vector for studying distinct physiological processes within a single organism. The uptake of Cd and associated isotopic fractionation was determined for both normal cells and those expressing CdCA. It was found that whole cells always exhibited a preference for the light isotopes of Cd, regardless of the expression of CdCA; adsorption of Cd to cell surfaces was not seen to cause isotopic fractionation. However, the cleaning procedure employed exerted a strong control on the observed isotopic composition of cells. Using existing protein purification techniques, we measured the Cd isotopic composition of different subcellular fractions of E

  14. SN 2011hw: helium-rich circumstellar gas and the luminous blue variable to Wolf-Rayet transition in supernova progenitors

    NASA Astrophysics Data System (ADS)

    Smith, Nathan; Mauerhan, Jon C.; Silverman, Jeffrey M.; Ganeshalingam, Mohan; Filippenko, Alexei V.; Cenko, S. Bradley; Clubb, Kelsey I.; Kandrashoff, Michael T.

    2012-11-01

    We present optical photometry and spectroscopy of the peculiar Type IIn/Ibn supernova (SN) 2011hw. Its optical light curve exhibits a slower decline rate than that of normal SNe Ibc, with a peak absolute magnitude of -19.5 (unfiltered) and a secondary rise 20-30 d later of -18.3 mag (R). Spectra of SN 2011hw are highly unusual compared to those of normal SN types, most closely resembling the spectra of SNe Ibn. We centre our analysis on comparing SN 2011hw to the well-studied Type Ibn SN 2006jc. While the two SNe have many important similarities, the differences are quite telling: compared to SN 2006jc, SN 2011hw has weaker He I and Ca II lines and relatively stronger H lines, its light curve exhibits a higher visual-wavelength luminosity and slower decline rate, and emission lines associated with the progenitor's circumstellar material (CSM) are narrower. One can reproduce the unusual continuum shape of SN 2011hw with roughly equal contributions from a 6000-K blackbody and a spectrum of SN 2006jc. We attribute this blackbody-like emission component and many other differences between the two SNe to a small amount of additional H in SN 2011hw, analogous to the small H mass that makes SNe IIb differ from SNe Ib. Slower speeds in the CSM and somewhat elevated H content suggest a connection between SN 2011hw's progenitor and Ofpe/WN9 stars, which have been associated with luminous blue variables (LBVs) in their hot quiescent phases, and are H poor - but not H free like classical Wolf-Rayet (WR) stars. Comparisons between SN 2011hw and SN 2006jc can be largely understood if their progenitors exploded at different points in the transitional evolution from an LBV to a WR star.

  15. Nitrogen isotope anomalies in primitive ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Sugiura, Naoji; Hashizume, Ko

    1992-07-01

    Large anomalies in nitrogen isotopic composition were found in two type-L3 ordinary chondrites. One of them is isotopically heavy, and the other is isotopically light. The carriers of anomalous nitrogen are partly soluble in HCl. Thus, the anomalies are probably due to new types of presolar grains, although they have not been identified yet. Trapped Ar-36 in these chondrites seems to be associated with this anomalous nitrogen, and may be presolar in origin. The presence of two different nitrogen isotopic anomalies suggests that the parent body of L chondrites, and also the primitive solar nebula, were not homogeneous. Nitrogen isotope anomalies seem to be useful in detecting subdivisions of chemical groups of chondrites.

  16. Efficient photocatalytic degradation of phenol in aqueous solution by SnO2:Sb nanoparticles

    NASA Astrophysics Data System (ADS)

    Al-Hamdi, Abdullah M.; Sillanpää, Mika; Bora, Tanujjal; Dutta, Joydeep

    2016-05-01

    Photodegradation of phenol in the presence of tin dioxide (SnO2) nanoparticles under UV light irradiation is known to be an effective photocatalytic process. However, phenol degradation under solar light is less effective due to the large band gap of SnO2. In this study antimony (Sb) doped tin dioxide (SnO2) nanoparticles were prepared at a low temperature (80 °C) by a sol-gel method and studied for its photocatalytic activity with phenol as a test contaminant. The catalytic degradation of phenol in aqueous media was studied using high performance liquid chromatography and total organic carbon measurements. The change in the concentration of phenol affects the pH of the solution due to the by-products formed during the photo-oxidation of phenol. The photoactivity of SnO2:Sb was found to be a maximum for 0.6 wt.% Sb doped SnO2 nanoparticles with 10 mg L-1 phenol in water. Within 2 h of photodegradation, more than 95% of phenol could be removed under solar light irradiation.

  17. SN X-ray Progenitor?

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Identifying stars that explode, right before they explode, is a tricky proposition since the end of starlife comes swiftly: in thermonuclear deflagrations, in nuclear exhaustion, or maybe in a rapid swirling merger of two dead stellar cores. On the right in the image above is an image of the galaxy NGC 1404 taken by the UV/optical Telescope (UVOT) on the Swift observatory. The circle surrounds SN 2007on, a supernova of Type Ia produced by the explosion of a white dwarf star in a binary system. These types of supernovae are important since they are believed to be 'standard candles', events which have the same intrinsic brightness which can serve as an important yardstick to measure cosmic distances. On the left is an image of the same galaxy taken by the Chandra X-ray observatory four years before the supernova. Conspicuous in the SN source circle is a bright source in the Chandra image, believed to be emission from a compact object+normal star companion: a similar system to the supposed precursor of SN 2007on. If true this would be the first time a Type Ia supernova precursor has ever been seen. But astronomers are still debating whether the Chandra source really is the precursor or not; it seems there's a slight but significant difference in the location of the Chandra source and the supernova. Stay tuned for more developments.

  18. Isotopic Variations of Mercury Emitted by Coal Fired Power Plant Gases

    NASA Astrophysics Data System (ADS)

    Khawaja, S. N.; Odom, L.; Landing, W.

    2010-12-01

    Emission of mercury from the burning of coal is considered one of the important anthropogenic sources of atmospheric mercury. Along with current measurements of the isotopic composition of atmospheric mercury being conducted in our laboratory, we have analyzed mercury emitted from a coal fired power plant. Previously Biswas and others (2008) had reported variations in the isotopic composition of mercury in a number of samples of coal deposits. Since the combustion of coal is expected to release virtually all of its mercury, we anticipated comparable isotopc patterns in coal and total emmited mercury. The emitted mercury exists in various physical and chemical forms, each possessing distinct properties that affect atmospheric transport, and sampling methods. Flue gas has been sampled in the stack of a coal fired electric power plant. The Ontario Hydro method was used to trap mercury in flue gases. The method uses oxidant solutions (KCl, H2O2-HNO3 and KMnO4-H2SO4) in its sampling train. This method is the modification of EPA method 29 with the use of KCl in the sampling train. Hg (II) is captured in the KCl impingers, while Hg (0) is captured in H2O2-HNO3 and KMnO4-H2SO4 impingers that oxidize elemental to Hg (ll) (EPA Draft, 1999). In addition gaseous reactive mercury was sampled downwind in large volume rain samples. Mercury (Hg+2) in sample solutions was reduced with SnCl2, and the generated Hg(0) vapor carried by Ar gas into the source of a NEPTUNE ICPMS-MC. Isotope ratios were measured by standard-sample bracketing and reported as permil deviations from the SRM NIST-3133 values. The measurement shows a small range of values of odd isotopes for mass independent fractionation which is negligible, However it displays the wide range of mass dependent fractionation (δ198 Hg -1.239 to 2.294). We found that samples in KCl impingers are light isotope enriched and depleted in heavy isotopes, while in KMnO4 impingers these are reverse.

  19. The expanding photosphere method applied to SN 1992am AT cz = 14 600 km/s

    NASA Technical Reports Server (NTRS)

    Schmidt, Brian P.; Kirshner, Robert P.; Eastman, Ronald G.; Hamuy, Mario; Phillips, Mark M.; Suntzeff, Nicholas B.; Maza, Jose; Filippenko, Alexei V.; Ho, Luis C.; Matheson, Thomas

    1994-01-01

    We present photometry and spectroscopy of Supernova (SN) 1992am for five months following its discovery by the Calan Cerro-Tololo Inter-American Observatory (CTIO) SN search. These data show SN 1992am to be type II-P, displaying hydrogen in its spectrum and the typical shoulder in its light curve. The photometric data and the distance from our own analysis are used to construct the supernova's bolometric light curve. Using the bolometric light curve, we estimate SN 1992am ejected approximately 0.30 solar mass of Ni-56, an amount four times larger than that of other well studied SNe II. SN 1992am's; host galaxy lies at a redshift of cz = 14 600 km s(exp -1), making it one of the most distant SNe II discovered, and an important application of the Expanding Photsphere Method. Since z = 0.05 is large enough for redshift-dependent effects to matter, we develop the technique to derive luminosity distances with the Expanding Photosphere Method at any redshift, and apply this method to SN 1992am. The derived distance, D = 180(sub -25) (sup +30) Mpc, is independent of all other rungs in the extragalactic distance ladder. The redshift of SN 1992am's host galaxy is sufficiently large that uncertainties due to perturbations in the smooth Hubble flow should be smaller than 10%. The Hubble ratio derived from the distance and redshift of this single object is H(sub 0) = 81(sub -15) (sup +17) km s(exp -1) Mpc(exp -1). In the future, with more of these distant objects, we hope to establish an independent and statistically robust estimate of H(sub 0) based solely on type II supernovae.

  20. Performing a stellar autopsy using the radio-bright remnant of SN 1996cr

    NASA Astrophysics Data System (ADS)

    Meunier, C.; Bauer, F. E.; Dwarkadas, V. V.; Koribalski, B.; Emonts, B.; Hunstead, R. W.; Campbell-Wilson, D.; Stockdale, C.; Tingay, S. J.

    2013-05-01

    We present newly reduced archival radio observations of SN 1996cr in the Circinus Galaxy from the Australia Telescope Compact Array and the Molonglo Observatory Synthesis Telescope, and attempt to model its radio light curves using recent hydrodynamical simulations of the interaction between the supernova (SN) ejecta and the circumstellar material (CSM) at X-ray wavelengths. The radio data within the first 1000 d show clear signs of free-free absorption (FFA), which decreases gradually and is minimal above 1.4 GHz after day ˜3000. Constraints on the FFA optical depth provide estimates of the CSM free electron density, which allows insight into the ionization of SN 1996cr's CSM and offers a test on the density distribution adopted by the hydrodynamical simulation. The intrinsic spectral index of the radiation shows evidence for spectral flattening, which is characterized by α = 0.852 ± 0.002 at day 3000 and a decay rate of Δα = -0.014 ± 0.001 yr-1. The striking similarity in the spectral flattening of SN 1987A, SN 1993J and SN 1996cr suggests this may be a relatively common feature of SNe/CSM shocks. We adopt this spectral index variation to model the synchrotron radio emission of the shock, and consider several scalings that relate the parameters of the hydrodynamical simulation to the magnetic field and electron distribution. The simulated light curves match the large-scale features of the observed light curves, but fail to match certain tightly constraining sections. This suggests that simple energy density scalings may not be able to account for the complexities of the true physical processes at work, or alternatively, that the parameters of the simulation require modification in order to accurately represent the surroundings of SN 1996cr.

  1. Modeling nuclear volume isotope effects in crystals.

    PubMed

    Schauble, Edwin A

    2013-10-29

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac-Hartree-Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor-crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from (119)Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium.

  2. Modeling nuclear volume isotope effects in crystals

    PubMed Central

    Schauble, Edwin A.

    2013-01-01

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac–Hartree–Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor–crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from 119Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium

  3. Modeling nuclear volume isotope effects in crystals

    NASA Astrophysics Data System (ADS)

    Schauble, Edwin A.

    2013-10-01

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac-Hartree-Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor-crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from 119Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium.

  4. Research into the microstructure and mechanical behavior of eutectic Bi-Sn and In-Sn

    SciTech Connect

    Goldstein, J.L.F.; Mei, Z.; Morris, J.W. Jr. |

    1993-08-01

    This manuscript reports on research into two low-melting, lead-free solder alloys, eutectic Bi-Sn and eutectic In-Sn. The microstructures were found to depend on both cooling rate and substrate, with the greatest variability in the In-Sn alloy. The nature of the intermetallic layer formed at the solder-substrate interface depends on both the solder and the substrate (Cu versus Ni). Also, the microstructure of the Bi-Sn can recrystallize during deformation, which is not the case with In-Sn. Data from creep and constant strain rate tests are given for slowly cooled samples. The creep behavior of In-Sn is constant with temperature, but the creep seems to be controlled by the In-rich phase in In-Sn on Cu and by the Sn-rich phase in In-Sn on Ni. Bi-Sn exhibits different creep behavior at temperatures above 40 {degrees}C than at 20 {degrees}C or lower. Stress-strain curves of Bi-Sn on Cu and In-Sn on Cu are similar, while In-Sn on Ni behaves differently. This is explained in terms of the deformation patterns in the alloys.

  5. Investigation of the Phase Equilibria of Sn-Cu-Au Ternary and Ag-Sn-Cu-Au Quaternary Systems and Interfacial Reactions in Sn-Cu/Au Couples

    NASA Astrophysics Data System (ADS)

    Yen, Yee-Wen; Jao, Chien-Chung; Hsiao, Hsien-Ming; Lin, Chung-Yung; Lee, Chiapyng

    2007-02-01

    The phase equilibria of the Sn-Cu-Au ternary, Ag-Sn-Cu-Au quaternary systems and interfacial reactions between Sn-Cu alloys and Au were experimentally investigated at specific temperatures in this study. The experimental results indicated that there existed three ternary intermetallic compounds (IMCs) and a complete solid solubility between AuSn and Cu6Sn5 phases in the Sn-Cu-Au ternary system at 200°C. No quaternary IMC was found in the isoplethal section of the Ag-Sn-Cu-Au quaternary system. Three IMCs, AuSn, AuSn2, and AuSn4, were found in all couples. The same three IMCs and (Au,Cu)Sn/(Cu,Au)6Sn5 phases were found in all Sn-Cu/Au couples. The thickness of these reaction layers increased with increasing temperature and time. The mechanism of IMC growth can be described by using the parabolic law. In addition, when the reaction time was extended and the Cu content of the alloy was increased, the AuSn4 phase disappeared gradually. The (Au, Cu)Sn and (Cu,Au)6Sn5 layers played roles as diffusion barriers against Sn in Sn-Cu/Au reaction couple systems.

  6. THE FIRST MAXIMUM-LIGHT ULTRAVIOLET THROUGH NEAR-INFRARED SPECTRUM OF A TYPE Ia SUPERNOVA

    SciTech Connect

    Foley, Ryan J.; Marion, G. Howie; Challis, Peter; Kirshner, Robert P.; Berta, Zachory K.; Kromer, Markus; Taubenberger, Stefan; Hillebrandt, Wolfgang; Roepke, Friedrich K.; Ciaraldi-Schoolmann, Franco; Seitenzahl, Ivo R.; Pignata, Giuliano; Stritzinger, Maximilian D.; Filippenko, Alexei V.; Li Weidong; Silverman, Jeffrey M.; Folatelli, Gaston; Hsiao, Eric Y.; Morrell, Nidia I.; Simcoe, Robert A.; and others

    2012-07-01

    We present the first maximum-light ultraviolet (UV) through near-infrared (NIR) Type Ia supernova (SN Ia) spectrum. This spectrum of SN 2011iv was obtained nearly simultaneously by the Hubble Space Telescope at UV/optical wavelengths and the Magellan Baade telescope at NIR wavelengths. These data provide the opportunity to examine the entire maximum-light SN Ia spectral energy distribution. Since the UV region of an SN Ia spectrum is extremely sensitive to the composition of the outer layers of the explosion, which are transparent at longer wavelengths, this unprecedented spectrum can provide strong constraints on the composition of the SN ejecta, and similarly the SN explosion and progenitor system. SN 2011iv is spectroscopically normal, but has a relatively fast decline ({Delta}m{sub 15}(B) = 1.69 {+-} 0.05 mag). We compare SN 2011iv to other SNe Ia with UV spectra near maximum light and examine trends between UV spectral properties, light-curve shape, and ejecta velocity. We tentatively find that SNe with similar light-curve shapes but different ejecta velocities have similar UV spectra, while those with similar ejecta velocities but different light-curve shapes have very different UV spectra. Through a comparison with explosion models, we find that both a solar-metallicity W7 and a zero-metallicity delayed-detonation model provide a reasonable fit to the spectrum of SN 2011iv from the UV to the NIR.

  7. Theory of the Helium Isotope Shift

    SciTech Connect

    Pachucki, Krzysztof; Yerokhin, V. A.

    2015-09-15

    Theory of the isotope shift of the centroid energies of light few-electron atoms is reviewed. Numerical results are presented for the isotope shift of the 2{sup 3}P-2{sup 3}S and 2{sup 1}S-2{sup 3}S transition energies of {sup 3}He and {sup 4}He. By comparing theoretical predictions for the isotope shift with the experimental results, the difference of the squares of the nuclear charge radii of {sup 3}He and {sup 4}He, δR{sup 2}, is determined with high accuracy.

  8. Updated Physical Parameters of SN 2012cg

    NASA Astrophysics Data System (ADS)

    Marion, G. H.; Challis, P.; Hicken, M.; Mandel, K.; Meyer, S.; Kirshner, R. P.; Foley, R. J.; Friedman, A.; Irwin, J.; Wood-Vasey, W. M.; Wheeler, J. C.; Vinko, J.; Rines, K.; Wilhelmy, S.; Macri, L.

    2012-06-01

    The Harvard-Smithsonian Center for Astrophysics Supernova Group reports photometric and spectroscopic observations of SN 2012cg (ATEL #4115, #4159). We find that SN 2012cg has a slow decline rate and low expansion velocities. BayeSN fits to the data show that SN 2012cg has significant dust extinction (A_v ~ 0.67 mag). We find R_v = 2.7 +/- 0.5, which is consistent with the Milky Way value of 3.1 and mildly inconsistent with the extremely low values reported for some highly reddened SN (e.g., R_v = 1.59 +/- 0.07 for SN 2002cv; Elias-Rosa et al.

  9. THE SUPERNOVA IMPOSTOR IMPOSTOR SN 1961V: SPITZER SHOWS THAT ZWICKY WAS RIGHT (AGAIN)

    SciTech Connect

    Kochanek, C. S.; Szczygiel, D. M.; Stanek, K. Z.

    2011-08-20

    SN 1961V, one of Zwicky's defining Type V supernovae (SNe), was a peculiar transient in NGC 1058 that has variously been categorized as either a true core-collapse SN leaving a black hole (BH) or neutron star (NS) remnant, or an eruption of a luminous blue variable star. The former case is suggested by its possible association with a decaying non-thermal radio source, while the latter is suggested by its peculiar transient light curve and its low initial expansion velocities. The crucial difference is that the star survives a transient eruption but not an SN. All stars identified as possible survivors are significantly fainter, L{sub opt} {approx} 10{sup 5} L{sub sun}, than the L{sub opt} {approx_equal} 3 x 10{sup 6} L{sub sun} progenitor star at optical wavelengths. While this can be explained by dust absorption in a shell of material ejected during the transient, the survivor must then be present as an L{sub IR} {approx_equal} 3 x 10{sup 6} L{sub sun} mid-infrared source. Using archival Spitzer observations of the region, we show that such a luminous mid-IR source is not present. The brightest source of dust emission is only L{sub IR} {approx_equal} 10{sup 5} L{sub sun} and does not correspond to the previously identified candidates for the surviving star. The dust cannot be made sufficiently distant and cold to avoid detection unless the ejection energy, mass, and velocity scales are those of an SN or greater. We conclude that SN 1961V was a peculiar, but real, SN. Its peculiarities are probably due to enhanced mass loss just prior to the SN, followed by the interactions of the SN blast wave with this ejecta. This adds to the evidence that there is a population of SN progenitors that have major mass-loss episodes shortly before core collapse. The progenitor is a low metallicity, {approx}1/3 solar, high-mass, M{sub ZAMS} {approx}> 80 M{sub sun}, star, which means either that BH formation can be accompanied by an SN or that surprisingly high-mass stars can form an

  10. Hydrogen sensing under ambient conditions using SnO₂ nanowires: synergetic effect of Pd/Sn codeposition.

    PubMed

    Jeong, Seung Ho; Kim, Sol; Cha, Junho; Son, Min Soo; Park, Sang Han; Kim, Ha-Yeong; Cho, Man Ho; Whangbo, Myung-Hwan; Yoo, Kyung-Hwa; Kim, Sung-Jin

    2013-01-01

    Semiconducting SnO2 nanowires deposited with Pd and Sn nanoparticles on their surface are shown to be a highly sensitive hydrogen sensor with fast response time at room temperature. Compared with the SnO2 nanowire deposited with Pd or Sn nanoparticles alone, the Pd/Sn-deposited SnO2 nanowire exhibits a significant improvement in the sensitivity and reversibility of sensing hydrogen gas in the air at room temperature. Our investigation indicates that two factors are responsible for the synergistic effect of Pd/Sn codeposition on SnO2 nanowires. One is that in the presence of Pd the oxidation of Sn nanoparticles on the surface of the SnO2 nanowire is incomplete leading only to suboxides SnOx (1 ≤ x < 2), and the other is that the surface of the Pd/Sn-deposited SnO2 nanowire is almost perfectly hydrophobic. PMID:24224874

  11. Lifetime measurements in light barium isotopes

    SciTech Connect

    Michelagnoli, C.; Angelis, G. de; Napoli, D. R.; Ur, C. A.; Brandolini, F.; Bazzacco, D.; Farnea, E.; Lenzi, S.; Lunardi, S.; Menegazzo, R.; Mengoni, D.; Pavan, P.; Rossi Alvarez, C.; Bizzeti, P. G.; Bizzeti-Sona, A. M.; Giannatiempo, A.; Nannini, A.; Sona, P.; Perego, A.; Tonev, D.

    2010-04-26

    The transition strengths for the low--lying levels of {sup 122,124}Ba have been determined analysing the Recoil Distance Doppler Shift data by the Differential Decay Curve Method. The trend of normalised B(E2) reveals a drop in correspondence of the 8{sub 1}{sup +} state. This feature is also present in {sup 122}Ba: entering the backbending region the interplay between collective and quasiparticle degrees of freedom have to be carefully taken into account.

  12. Asiago spectroscopic classification of SN 2016eob

    NASA Astrophysics Data System (ADS)

    Ochner, P.; Tomasella, G. Terreran L.; Pastorello, A.; Benetti, S.; Cappellaro, E.; Elias-Rosa, N.; Turatto, M.; Yang, S.

    2016-08-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classification of SN 2016eob. The transient was discovered by Leonini et al. 2016, TNS Astronomical Transient Report No. 3994, Italian Supernovae Search Project (ISSP), on UT 2016-08-03.11 in the galaxy UGC00005 (2 other supernovae exploded in this host: SN 2000da, SN 2003lq).

  13. Method for separating isotopes

    DOEpatents

    Jepson, B.E.

    1975-10-21

    Isotopes are separated by contacting a feed solution containing the isotopes with a cyclic polyether wherein a complex of one isotope is formed with the cyclic polyether, the cyclic polyether complex is extracted from the feed solution, and the isotope is thereafter separated from the cyclic polyether.

  14. Stable isotope studies

    SciTech Connect

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

  15. Direct preparation of Cu2ZnSnSe4 films by microwave irradiation and its dependence on the Sn/(Sn + Zn) ratio

    NASA Astrophysics Data System (ADS)

    Kaigawa, Ryuji; Hashimoto, Shintaro; Irago, Tomoki; Klenk, Reiner

    2015-08-01

    Cu2ZnSnSe4 (CZTSe) films with various Sn/(Sn + Zn) ratios were directly prepared on metallic Ti foils by microwave irradiation and their properties were investigated. The Sn/(Sn + Zn) ratio and Cu/(Sn + Zn) ratio of the precursor could be preserved by using a sealed container filled with 0.15 atm of Ar. Single-phase CZTSe crystals with a kesterite (stannite) structure and without by-products were observed with Sn/(Sn + Zn) ratios between 0.4 and 0.6. The hole densities of the Cu-Zn-Sn-Se films are minimal (<1017/cm3) with Sn/(Sn + Zn) ratios ranging from 0.5 to 0.6.

  16. The Curious Case of SN 2011dn: Was It A Peculiar Type Ia Supernova?

    NASA Astrophysics Data System (ADS)

    Rachubo, Alisa; Salvo, Chris; Leonard, Douglas C.; Duong, Nhieu; Horst, Chuck; Khandrika, Harish G.; Sumandal, Julienne; Moustakas, John

    2014-06-01

    Type Ia supernovae (SNe Ia) are excellent cosmological distance indicators due to the uniformity in their light curves. This led to the major discovery of the accelerated expansion of the universe (Riess et al. 1998, Perlmutter et al. 1999). However, SNe Ia are not so uniform as one may expect, as there are many ‘peculiar’ SNe Ia that exhibit differences in photometry and spectroscopy from normal SNe Ia. One of the goals of supernova cosmology today is to produce a cleaner sample of SNe Ia by removing the peculiar SNe Ia from the sample. A useful parameter for identifying peculiar SNe Ia based on photometry is Δm15(B), which measures the decrease in B-band magnitude 15 days after the peak of the light curve (Phillips et al. 1993). For typical SNe Ia the standard value is Δm15(B) = 1.1. Peculiar SNe Ia of the overluminous type show a slower decline, with its prototypical member SN 1991T having Δm15(B) = 0.80 (Hicken et al. 2009), while peculiar SNe Ia of the subluminous type show a faster decline, with its prototypical member SN 1991bg having Δm15(B) = 1.87 (Hicken et al. 2009). Here we present optical photometry and spectroscopy of SN 2011dn, which were obtained as part of the MOunt LAguna SUpernova Survey (MOLASUS). Based on its pre-maximum spectrum, which showed strong absorption lines of Fe III λ4404 and Fe III λ5129, along with a weak Si II λ6355 absorption line, SN 2011dn was classified as a SN 1991T-like event (Koff et al. 2011). However, in an earlier preliminary analysis of the light curves - based on point-spread-function photometry - we proposed that SN 2011dn might have had a higher than expected Δm15(B) value of 1.08 (Salvo et al. 2012). Since SN 2011dn is embedded in its host galaxy UGC 11501, it is possible that some of the light from the host galaxy was measured, which may have influenced the measured Δm15(B) value. Here, we employ galaxy-subtraction techniques to isolate the supernova light from its host galaxy, and generate more

  17. SN 1987A Transforms into SN Remnant 1987A

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin; Heathcote, Stephen; Lawrence, Stephen

    2014-08-01

    The ejecta and circumstellar ring of SN 1987A are colliding violently. Over several years, we have seen radical changes in the circumstellar nebula as it is overrun by high-speed ejecta, giving birth to a supernova remnant (SNR). We have already discovered (and published), via this observational program, new interactions between ejecta and nebula, as several hot spots appearing every year, and see now the whole innermost nebula interacting. This means that observations, especially spectroscopy, of SNR 1987A have entered a new phase in which ground-based observations can reveal the collective behavior of the SNR, especially when combined with HST data. The collision is predicted (and observed) to produce intense IR/optical emission, in new and previously-observed lines. Depending on whether these arise in the ejecta or nebula, and whether shock or EUV-excited, they have linewidths ~10 to 15,000 km/s; frequent moderate- dispersion spectra are required. With the interaction region now enveloping the inner ring, ionizing radiation has started flooding the entire structure. SOAR/Goodman is ideal for this, covering velocity scales, wavelengths and time intervals unavailable to HST, allowing the first ever study of the creation of a nearby SNR. In particular we need timely, good-seeing Goodman spectra of the reverse shock of SN 1987A's circumstellar/ejecta interaction this semester to combine with our scheduled HST/STIS spectra and WFC3 images (in August 2014) and thereby measure of the compositon of deep layers in the SN progenitor star by studying ionic species measurements not seen by HST data alone.

  18. Radio Observations of SN 2006jc

    NASA Astrophysics Data System (ADS)

    Soderberg, Alicia

    2006-10-01

    "I observed the Type Ib SN 2006jc (CBET 666) with the Very Large Array on Oct 14.7 and Oct 15.7 UT as part of an ongoing program to study the radio properties of Type Ibc supernovae. SN 2006jc is not detected at 4.9, 8.5 or 22.5 GHz. At a distance of 24 Mpc, the radio luminosity of SN 2006jc is at least a factor of 100 lower than that of SN 1998bw at a similar epoch (Kulkarni et al., 1998, Nature, 395, 663).

  19. Pseudomorphic GeSn/Ge (001) heterostructures

    SciTech Connect

    Tonkikh, A. A.; Talalaev, V. G.; Werner, P.

    2013-11-15

    The synthesis of pseudomorphic GeSn heterostructures on a Ge (001) substrate by molecular-beam epitaxy is described. Investigations by transmission electron microscopy show that the GeSn layers are defect free and possess cubic diamondlike structure. Photoluminescence spectroscopy reveals interband radiative recombination in the GeSn quantum wells, which is identified as indirect transitions between the subbands of heavy electrons and heavy holes. On the basis of experimental data and modeling of the band structure of pseudomorphic GeSn compounds, the lower boundary of the bowing parameter for the indirect band gap is estimated as b{sub L} {>=} 1.47 eV.

  20. Comparative analysis of cross sections of residual nuclei on separated tin isotopes at a beam energy of protons and deuterons 3.65 GeV/nucleon

    SciTech Connect

    Balabekyan, A. R.; Demekhina, N. A.; Simonyan, A. E.

    2013-03-15

    The cross sections of residual nuclei in the separated tin isotopes ({sup 112}Sn, {sup 118}Sn, {sup 120}Sn, and {sup 124}Sn), irradiated with proton and deuteron beams with energy 3.65 GeV/nucleon, are investigated. Parametrization by ten parametric semi-empirical formula was conducted with the aim of determining the total cross sections and analyzing the measurement results. The dependence of total inelastic cross sections on the mass number of the target and the structure of the incoming particle was investigated via the comparison of the obtained data.

  1. Generalized seniority and E 2 transitions in the tin isotopes

    NASA Astrophysics Data System (ADS)

    Morales, Irving O.; Van Isacker, P.; Talmi, I.

    2011-09-01

    Recently, a shallow minimum was discovered in B(E2) values in even Sn isotopes around the middle of the neutron major shell. A peak in that region was expected according to calculations using generalized seniority. In a model calculation we show that the observed shape is consistent with generalized seniority. It seems to be due to the order of filling of j-orbits.

  2. Isotope separation by photochromatography

    DOEpatents

    Suslick, K.S.

    1975-10-03

    A photochromatographic method for isotope separation is described. An isotopically mixed molecular species is adsorbed on an adsorptive surface, and the adsorbed molecules are irradiated with radiation of a predetermined wavelength which will selectively excite desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thus separate them from the undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes. (BLM)

  3. Isotope separation by photochromatography

    DOEpatents

    Suslick, Kenneth S.

    1977-01-01

    An isotope separation method which comprises physically adsorbing an isotopically mixed molecular species on an adsorptive surface and irradiating the adsorbed molecules with radiation of a predetermined wavelength which will selectively excite a desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thereby separate them from the unexcited undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes.

  4. Quark nova imprint in the extreme supernova explosion SN 2006gy

    NASA Astrophysics Data System (ADS)

    Ouyed, R.; Kostka, M.; Koning, N.; Leahy, D. A.; Steffen, W.

    2012-06-01

    The extremely luminous supernova 2006gy (SN 2006gy) is among the most energetic ever observed. The peak brightness was 100 times that of a typical supernova and it spent an unheard of 250 d at magnitude -19 or brighter. Efforts to describe SN 2006gy have pushed the boundaries of current supernova theory. In this work we aspire to simultaneously reproduce the photometric and spectroscopic observations of SN 2006gy using a quark nova (QN) model. This analysis considers the supernova explosion of a massive star followed days later by the QN detonation of a neutron star. We lay out a detailed model of the interaction between the supernova envelope and the QN ejecta paying special attention to a mixing region which forms at the inner edge of the supernova envelope. This model is then fitted to photometric and spectroscopic observations of SN 2006gy. This QN model naturally describes several features of SN 2006gy including the late-stage light-curve plateau, the broad Hα line and the peculiar blue Hα absorption. We find that a progenitor mass between 20 and 40 M⊙ provides ample energy to power SN 2006gy in the context of a QN.

  5. Preparation of C60 Nanowhiskers-SnO2 Nanocomposites and Photocatalytic Degradation of Organic Dyes.

    PubMed

    Park, Hae Soo; Ko, Weon Bae

    2015-10-01

    C60 nanowhiskers were prepared using a liquid-liquid interfacial precipitation (LLIP) method. Tin oxide (SnO2) nanoparticles were synthesized by a reaction of tin (IV) chloride pentahydrate with ammonium nitrate in an electric furnace. The C60 nanowhiskers-SnO2 nanocomposites were calcined in an electric furnace at 700 °C under an inert argon gas atmosphere for 2 h. The crystallinity, morphology and optical properties of the samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and UV-vis spectrophotometry. The photocatalytic activity of the C60 nanowhiskers-SnO2 nanocomposites in the degradation of the organic dyes, such as methylene blue, methyl orange, rhodamine B, and brilliant green, under ultraviolet light at 254 nm by UV-vis spectrophotometry was evaluated and compared with that of C60 nanowhiskers and SnO2 nanoparticles. The experimental results showed that C60 nanowhiskers-SnO2 nanocomposites exhibited remarkably higher photocatalytic degradation of organic dyes compared to C60 nanowhiskers and SnO2 nanoparticles.

  6. Preparation of C60 Nanowhiskers-SnO2 Nanocomposites and Photocatalytic Degradation of Organic Dyes.

    PubMed

    Park, Hae Soo; Ko, Weon Bae

    2015-10-01

    C60 nanowhiskers were prepared using a liquid-liquid interfacial precipitation (LLIP) method. Tin oxide (SnO2) nanoparticles were synthesized by a reaction of tin (IV) chloride pentahydrate with ammonium nitrate in an electric furnace. The C60 nanowhiskers-SnO2 nanocomposites were calcined in an electric furnace at 700 °C under an inert argon gas atmosphere for 2 h. The crystallinity, morphology and optical properties of the samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and UV-vis spectrophotometry. The photocatalytic activity of the C60 nanowhiskers-SnO2 nanocomposites in the degradation of the organic dyes, such as methylene blue, methyl orange, rhodamine B, and brilliant green, under ultraviolet light at 254 nm by UV-vis spectrophotometry was evaluated and compared with that of C60 nanowhiskers and SnO2 nanoparticles. The experimental results showed that C60 nanowhiskers-SnO2 nanocomposites exhibited remarkably higher photocatalytic degradation of organic dyes compared to C60 nanowhiskers and SnO2 nanoparticles. PMID:26726474

  7. Sn2SiS4, synthesis, structure, optical and electronic properties

    NASA Astrophysics Data System (ADS)

    Li, Chao; Lin, Zuohong; Kang, Lei; Lin, Zheshuai; Huang, Hongwei; Yao, Jiyong; Wu, Yicheng

    2015-09-01

    The new ternary sulfide Sn2SiS4 has been synthesized via high-temperature solid state reaction. It crystallizes in the centrosymmetric space group P21/c of the monoclinic system. In the structure, the Sn2+ cations are coordinated to a heavily-distorted octahedron of six S atoms or a pentagonal pyramid of six S atoms, both geometries clearly demonstrating the effect of the stereo-chemically active electron lone pair on the Sn coordination environment. These SnS6 polyhedra and the SiS4 tetrahedra are connected to each other via corner and edge-sharing to generate a three-dimensional framework. Based on the diffuse reflectance measurement and the electronic structure calculation, Sn2SiS4 has an indirect band gap of 2.00 eV. Interestingly, Sn2SiS4 exhibits an efficient visible-light-driven photocatalytic activity pertaining to Rhodamine B (RhB) degradation, which is superior to the important photocatalyst C3N4. Moreover, the photocatalytic mechanism was also elucidated based on the active species trapping experiments.

  8. SNLS: Constraints on SN Ia progenitors from host galaxies

    NASA Astrophysics Data System (ADS)

    Howell, D. A.; Sullivan, M.; Le Borgne, D.; Hodsman, A.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Conley, A.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I. M.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Baumont, S.; Bronder, T. J.; Filliol, M.; Perlmutter, S.; Tao, C.; SNLS Collaboration

    2005-12-01

    We investigate the single degenerate and double degenerate progenitor scenarios for SNe Ia using Pegase galaxy population synthesis models fit to the SN Ia host galaxy ugriz data from the SNLS. For the single degenerate scenario, we present the results of a Monte Carlo sumulation combining limits on the star formation history of the model hosts and analytic contraints on the allowable primary and secondary mass distributions. Under the assuption that all SNe are from the single degenerate channel, we find that SNe in star forming galaxies have a wide range of secondary masses, with a median of about 5 solar masses. Supernovae from the older galaxy population must come from a narrower distribution of secondary masses, with a median less than two solar masses. When combined with the differing stretch distributions for the two populations, this argues that there is a light curve shape-secondary mass correlation if the single degenerate model is the only route to an SN Ia. However, the single degenerate scenario has difficulty producing the observed SN Ia rate in old populations so the double degenerate scenario may be preferred.

  9. Radio evolution of supernova SN 2008iz in M 82

    NASA Astrophysics Data System (ADS)

    Kimani, N.; Sendlinger, K.; Brunthaler, A.; Menten, K. M.; Martí-Vidal, I.; Henkel, C.; Falcke, H.; Muxlow, T. W. B.; Beswick, R. J.; Bower, G. C.

    2016-08-01

    We report on multi-frequency Very Large Array (VLA) and Very Long Baseline Interferometry (VLBI) radio observations for a monitoring campaign of supernova SN 2008iz in the nearby irregular galaxy M 82. We fit two models to the data, a simple time power-law, S ∝ tβ, and a simplified Weiler model, yielding decline indices of β = -1.22 ± 0.07 (days 100-1500) and -1.41 ± 0.02 (days 76-2167), respectively. The late-time radio light-curve evolution shows flux-density flares at ~970 and ~1400 days that are a factor of ~2 and ~4 higher than the expected flux, respectively. The later flare, except for being brighter, does not show signs of decline at least from results examined so far (2014 January 23; day 2167). We derive the spectral index, α, S ∝ να for frequencies 1.4 to 43 GHz for SN 2008iz during the period from ~430 to 2167 days after the supernova explosion. The value of α shows no signs of evolution and remains steep ≈-1 throughout the period, unlike that of SN 1993J, which started flattening at ~day 970. From the 4.8 and 8.4 GHz VLBI images, the supernova expansion is seen to start with a shell-like structure that becomes increasingly more asymmetric, then breaks up in the later epochs, with bright structures dominating the southern part of the ring. This structural evolution differs significantly from SN 1993J, which remains circularly symmetric over 4000 days after the explosion. The VLBI 4.8 and 8.4 GHz images are used to derive a deceleration index, m, for SN 2008iz, of 0.86 ± 0.02, and the average expansion velocity between days 73 and 1400 as (12.1 ± 0.2) × 103 km s-1. From the energy equipartition between magnetic field and particles, we estimate the minimum total energy in relativistic particles and the magnetic fields during the supernova expansion and also find the magnetic field amplification factor for SN 2008iz to be in the range of 55-400. The VLBI images (FITS files) are only available at the CDS via anonymous ftp to http

  10. Stable Isotope Evidence for Planetary Differentiation

    NASA Astrophysics Data System (ADS)

    Shahar, A.; Mao, W. L.; Schauble, E. A.; Caracas, R.; Reagan, M. M.; Gleason, A. E.

    2015-12-01

    Planetary differentiation occurred at high temperature and varying oxygen fugacity, on bodies with varying compositions and internal pressures. The specific conditions at which bodies differentiated and the chemical fingerprints left by differentiation can be investigated by measuring stable isotope ratios in natural samples. Much can be learned by combining those data with experiments that systematically investigate the chemical and physical conditions within differentiating bodies. In this talk we focus on one variable in particular that has not been well defined with respect to stable isotope fractionation: pressure. We will present new iron isotope data on how pressure affects isotope fractionation factors for a number of iron compounds relative to silicate. The processes governing iron isotope fractionation in igneous rocks have been debated extensively over the past decade. Analyses of natural samples show that iron isotopes are fractionated at both the whole rock and mineral scales. This fractionation has been interpreted to be a result of several processes including a possible signature of high pressure core formation. We have collected new high pressure synchrotron nuclear resonant inelastic x-ray scattering data from Sector 16-ID-D at the Advanced Photon Source on 57Fe enriched Fe, FeO, FeHx and Fe3C. Our data show clear trends with pressure implying that not only does pressure have an effect on the iron isotope beta factors but also a fractionation amongst the alloys. This suggests that depending on the light element in the core, there will be a different resulting signature in the iron isotope record. We will discuss the likelihood of different light elements in the core based on these results, as well as the theoretical predictions for the same phases. Finally, we will present the fractionation expected between metal and silicate at high pressure and high temperature in order to determine if core formation would indeed leave an isotopic signature in

  11. In2O3/Bi2Sn2O7 heterostructured nanoparticles with enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Xing, Yonglei; Que, Wenxiu; Yin, Xingtian; He, Zuoli; Liu, Xiaobin; Yang, Yawei; Shao, Jinyou; Kong, Ling Bing

    2016-11-01

    In2O3/Bi2Sn2O7 composite photocatalysts with various contents of cubic In2O3 nanoparticles were fabricated by using impregnation method. A thriving modification of Bi2Sn2O7 by an introduction of In2O3 was confirmed by using X-ray diffraction, UV-vis diffuse reflectance spectrometry, transmission electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The samples composed of hybrids of In2O3 and Bi2Sn2O7 exhibited a much higher photocatalytic activity for the degradation of Rhodamine B under visible light, as compared with pure In2O3 and Bi2Sn2O7 nanoparticles. Optimized composition of the composite photocatalysts was 0.1In2O3/Bi2Sn2O7, which shows a rate constant higher than those of pure In2O3 and Bi2Sn2O7 by 4.06 and 3.21 times, respectively. Based on Mott-Schottky analysis and active species detection, the photoexcited electrons in the conduction band of In2O3 and the holes in the valence band of Bi2Sn2O7 participated in reduction and oxidation reactions, respectively. Hence, rad OH, rad O2- and h+ were the main active species involved in the photocatalytic reaction of the In2O3/Bi2Sn2O7 composite photocatalysts. The effective separation process of the photogenerated electron-hole pairs was testified by photocurrent test.

  12. Clues to the nature of SN 2009ip from photometric and spectroscopic evolution to late times

    SciTech Connect

    Graham, M. L.; Sand, D. J.; Valenti, S.; Howell, D. A.; Parrent, J.; Halford, M.; Zaritsky, D.; Bianco, F.; Rest, A.; Dilday, B.

    2014-06-01

    We present time series photometric and spectroscopic data for the transient SN 2009ip from the start of its outburst in 2012 September until 2013 November. These data were collected primarily with the new robotic capabilities of the Las Cumbres Observatory Global Telescope Network, a specialized facility for time domain astrophysics, and includes supporting high-resolution spectroscopy from the Southern Astrophysical Research Telescope, Kitt Peak National Observatory, and Gemini Observatory. Based on our nightly photometric monitoring, we interpret the strength and timing of fluctuations in the light curve as interactions between fast-moving ejecta and an inhomogeneous circumstellar material (CSM) produced by past eruptions of this massive luminous blue variable (LBV) star. Our time series of spectroscopy in 2012 reveals that, as the continuum and narrow Hα flux from CSM interactions declines, the broad component of Hα persists with supernova (SN)-like velocities that are not typically seen in LBVs or SN impostor events. At late times, we find that SN 2009ip continues to decline slowly, at ≲ 0.01 mag day{sup –1}, with small fluctuations in slope similar to Type IIn supernovae (SNe IIn) or SN impostors but no further LBV-like activity. The late-time spectrum features broad calcium lines similar to both late-time SNe and SN impostors. In general, we find that the photometric and spectroscopic evolution of SN 2009ip is more similar to SNe IIn than either continued eruptions of an LBV star or SN impostors but we cannot rule out a nonterminal explosion. In this context, we discuss the implications for episodic mass loss during the late stages of massive star evolution.

  13. Structural optical correlated properties of SnO2/Al2O3 core@ shell heterostructure

    NASA Astrophysics Data System (ADS)

    Heiba, Zein K.; Imam, N. G.; Bakr Mohamed, Mohamed

    2016-07-01

    Nano size polycrystalline samples of the core@shell heterostructure of SnO2 @ xAl2O3 (x = 0, 25, 50, 75 wt.%) were synthesized by sol-gel technique. The resulting samples were characterized with fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and X-ray powder diffraction (XRD). The XRD patterns manifest diffraction peaks of SnO2 as main phase with weak peaks corresponding to Al2O3 phase. The formation of core@ shell structure is confirmed by TEM images and Rietveld quantitative phase analysis which revealed that small part of Al2O3 is incorporated into the SnO2 lattice while the main part (shell) remains as a separate phase segregated on the grain boundary surface of SnO2 (core). It is found that the grain size of the mixed oxides SnO2 @ xAl2O3 is below 10 nm while for pure SnO2 it is over 41 nm, indicating that alumina can effectively prevent SnO2 from further growing up in the process of calcination. This is confirmed by the large increase in the specific surface area for mixed oxide samples. The PL emission showed great dependence on the structure properties analyzed by XRD and FTIR. The PL results recommend Al2O3@SnO2 core@shell heterostructure to be a promising short-wavelength luminescent optoelectronic devices for blue, UV, and laser light-emitting diodes.

  14. Calcium isotopes in wine

    NASA Astrophysics Data System (ADS)

    Holmden, C. E.

    2011-12-01

    Merlot grapes was -1.94%, which is lower than any of the bottled wines measured, thus far, whether white or red. The wine made from this juice yielded -1.16%, which points to fermentation being the principal source of isotopic variability found in bottled wine. The working hypothesis is that light isotopes of Ca are preferentially stripped from the juice during maceration, fermentation, and lees contact, by ion exchange sites on solid organic-matter comprising the skins and yeast and/or by Ca-tartrate precipitation. High quality wines (especially reds) tend to involve longer contact times between juice and skins in order to increase the extraction of color and phenolic compounds (tannins) from the grape skins, a practice that might also result in greater losses of light isotopes of Ca from the juice, thus explaining the isotopic pattern in bottled wine.

  15. Pristine extraterrestrial material with unprecedented nitrogen isotopic variation

    PubMed Central

    Briani, Giacomo; Gounelle, Matthieu; Marrocchi, Yves; Mostefaoui, Smail; Leroux, Hugues; Quirico, Eric; Meibom, Anders

    2009-01-01

    Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, highly pristine mineralogy has similarity with interplanetary dust particles (IDPs), but the volume of the xenolith is more than 30,000 times that of a typical IDP. Furthermore, an extreme continuum of N isotopic variation is present in this xenolith: from very light N isotopic composition (δ15NAIR = −310 ± 20‰), similar to that inferred for the solar nebula, to the heaviest ratios measured in any solar system material (δ15NAIR = 4,900 ± 300‰). At the same time, its hydrogen and carbon isotopic compositions exhibit very little variation. This object poses serious challenges for existing models for the origin of light element isotopic anomalies. PMID:19528640

  16. Pristine extraterrestrial material with unprecedented nitrogen isotopic variation.

    PubMed

    Briani, Giacomo; Gounelle, Matthieu; Marrocchi, Yves; Mostefaoui, Smail; Leroux, Hugues; Quirico, Eric; Meibom, Anders

    2009-06-30

    Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, highly pristine mineralogy has similarity with interplanetary dust particles (IDPs), but the volume of the xenolith is more than 30,000 times that of a typical IDP. Furthermore, an extreme continuum of N isotopic variation is present in this xenolith: from very light N isotopic composition (delta(15)N(AIR) = -310 +/- 20 per thousand), similar to that inferred for the solar nebula, to the heaviest ratios measured in any solar system material (delta(15)N(AIR) = 4,900 +/- 300 per thousand). At the same time, its hydrogen and carbon isotopic compositions exhibit very little variation. This object poses serious challenges for existing models for the origin of light element isotopic anomalies. PMID:19528640

  17. THE RISE OF SN 2014J IN THE NEARBY GALAXY M82

    SciTech Connect

    Goobar, A.; Johansson, J.; Amanullah, R.; Ferretti, R.; Cao, Y.; Perley, D. A.; Tendulkar, S. P.; Kasliwal, M. M.; Nugent, P. E.; Harris, C.; Gal-Yam, A.; Ofek, E. O.; Dennefeld, M.; Valenti, S.; Arcavi, I.; Banerjee, D. P. K.; Venkataraman, V.; Joshi, V.; Ashok, N. M.; Cenko, S. B.; and others

    2014-03-20

    We report on the discovery of SN 2014J in the nearby galaxy M82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova (SN) over a wide range of the electromagnetic spectrum. Optical, near-IR, and mid-IR observations on the rising light curve, orchestrated by the intermediate Palomar Transient Factory, show that SN 2014J is a spectroscopically normal Type Ia supernova (SN Ia), albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the light curve rise. Similar to other highly reddened SNe Ia, a low value of total-to-selective extinction, R{sub V} ≲ 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from Hubble Space Telescope with special emphasis on the sources nearest to the SN location.

  18. EARLY- AND LATE-TIME OBSERVATIONS OF SN 2008ha: ADDITIONAL CONSTRAINTS FOR THE PROGENITOR AND EXPLOSION

    SciTech Connect

    Foley, Ryan J.; Challis, Peter J.; Kirshner, Robert P.; Brown, Peter J.; Rest, Armin; Wood-Vasey, W. Michael

    2010-01-01

    We present a new maximum-light optical spectrum of the extremely low luminosity and exceptionally low-energy Type Ia supernova (SN Ia) 2008ha, obtained one week before the earliest published spectrum. Previous observations of SN 2008ha were unable to distinguish between a massive star and white dwarf (WD) origin for the SN. The new maximum-light spectrum, obtained one week before the earliest previously published spectrum, unambiguously shows features corresponding to intermediate mass elements, including silicon, sulfur, and carbon. Although strong silicon features are seen in some core-collapse SNe, sulfur features, which are a signature of carbon/oxygen burning, have always been observed to be weak in such events. It is therefore likely that SN 2008ha was the result of a thermonuclear explosion of a carbon-oxygen WD. Carbon features at maximum light show that unburned material is present to significant depths in the SN ejecta, strengthening the case that SN 2008ha was a failed deflagration. We also present late-time imaging and spectroscopy that are consistent with this scenario.

  19. Isotopically Modified Molybdenum: Production for Application in Nuclear Energy

    NASA Astrophysics Data System (ADS)

    Smirnov, A. Yu.; Bonarev, A. K.; Sulaberidze, G. A.; Borisevich, V. D.; Kulikov, G. G.; Shmelev, A. N.

    The possibility to use the isotopically modified molybdenum as a constructive material for the fuel rods of light water and fast reactors is discussed. The calculations demonstrate that the isotopically modified molybdenum with an average neutron absorption cross-section comparable to that of zirconium can be obtained with the reasonable for practice cost by a cascade of gas centrifuges, specially designed for separation of non-uranium isotopes.

  20. LSND, SN1987A, and CPT violation

    SciTech Connect

    Murayama, Hitoshi; Yanagida, T.

    2000-10-17

    We point out that neutrino events observed at Kamiokande andIMB from SN1987A disfavor the neutrino oscillation parameters preferredby the LSND experiment. For Delta m2>0 (the light side), theelectron neutrinos from the neutronization burst would be lost, while thefirst event at Kamiokande is quite likely to be due to an electronneutrino. For Delta m2<0 (the dark side), the average energy of thedominantly bar nu e events is already lower than the theoreticalexpectations, which would get aggravated by a complete conversion frombar nu mu to bar nu e. If taken seriously, the LSND data are disfavoredindependent of the existence of a sterile neutrino. A possible remedy isCPT violation, which allows different mass spectra for neutrinos andanti-neutrinos and hence can accommodate atmospheric, solar and LSND datawithout a sterile neutrino. If this is the case, Mini-BooNE must run inbar nu rather than the planned nu mode to test the LSND signal. Wespeculate on a possible origin of CPT violation.

  1. Two-solvent method synthesis of SnO{sub 2} nanoparticles embedded in SBA-15: Gas-sensing and photocatalytic properties study

    SciTech Connect

    Dai, Peng; Zhang, Lili; Li, Guang; Sun, Zhaoqi; Liu, Xiansong; Wu, Mingzai

    2014-02-01

    Graphical abstract: Different loadings of SnO{sub 2} nanoparticles embedded in mesoporous silica (sample S1, S2 and S3) show higher response to H{sub 2} at lower operating temperature than pure SnO{sub 2} nanoparticles. - Highlights: • Two-solvent method is firstly used to synthesize SnO{sub 2} nanoparticles embedded in mesoporous silica (SBA-15). • The SnO{sub 2}/SBA-15 nanocomposites show higher response to H{sub 2} at lower operating temperature than pure SnO{sub 2} nanoparticles. • The SnO{sub 2}/SBA-15 nanocomposites have higher photodegradation ability toward methylene blue than pure SnO{sub 2} nanoparticles. - Abstract: Different loadings of SnO{sub 2} nanoparticles embedded in mesoporous silica (SBA-15) were prepared via a two-solvent method with the ordered hexagonal mesoporous structure of SBA-15 kept. X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy and N{sub 2} adsorption porosimetry were employed to characterize the nanocomposites. Compared with pure SnO{sub 2} nanoparticles, the SnO{sub 2}/SBA-15 nanocomposites show higher response to H{sub 2} at lower operating temperature. The photocatalytic activity of as-prepared SnO{sub 2}/SBA-15 for degradation of methylene blue was investigated under UV light irradiation and the results show that the SnO{sub 2}/SBA-15 nanocomposites have higher photodegradation ability toward methylene blue than pure SnO{sub 2} nanoparticles.

  2. Calorimetric studies of Cu-Li, Li-Sn, and Cu-Li-Sn.

    PubMed

    Fürtauer, S; Tserenjav, E; Yakymovych, A; Flandorfer, H

    2013-06-01

    Integral molar enthalpies of mixing were determined by drop calorimetry for Cu-Li-Sn at 1073 K along five sections xCu/xSn ≈ 1:1, xCu/xSn ≈ 2:3, xCu/xSn ≈ 1:4, xLi/xSn ≈ 1:1, and xLi/xSn ≈ 1:4. The integral and partial molar mixing enthalpies of Cu-Li and Li-Sn were measured at the same temperature, for Li-Sn in addition at 773 K. All binary data could be described by Redlich-Kister-polynomials. Cu-Li shows an endothermic mixing effect with a maximum in the integral molar mixing enthalpy of ∼5300 J · mol(-1) at xCu = 0.5, Li-Sn an exothermic minimum of ∼ -37,000 J · mol(-1) at xSn ∼ 0.2. For Li-Sn no significant temperature dependence between 773 K and 1073 K could be deduced. Our measured ternary data were fitted on the basis of an extended Redlich-Kister-Muggianu model for substitutional solutions. Additionally, a comparison of these results to the extrapolation model of Chou is given.

  3. Calorimetric studies of Cu–Li, Li–Sn, and Cu–Li–Sn

    PubMed Central

    Fürtauer, S.; Tserenjav, E.; Yakymovych, A.; Flandorfer, H.

    2013-01-01

    Integral molar enthalpies of mixing were determined by drop calorimetry for Cu–Li–Sn at 1073 K along five sections xCu/xSn ≈ 1:1, xCu/xSn ≈ 2:3, xCu/xSn ≈ 1:4, xLi/xSn ≈ 1:1, and xLi/xSn ≈ 1:4. The integral and partial molar mixing enthalpies of Cu–Li and Li–Sn were measured at the same temperature, for Li–Sn in addition at 773 K. All binary data could be described by Redlich–Kister-polynomials. Cu–Li shows an endothermic mixing effect with a maximum in the integral molar mixing enthalpy of ∼5300 J · mol−1 at xCu = 0.5, Li–Sn an exothermic minimum of ∼ −37,000 J · mol−1 at xSn ∼ 0.2. For Li–Sn no significant temperature dependence between 773 K and 1073 K could be deduced. Our measured ternary data were fitted on the basis of an extended Redlich–Kister–Muggianu model for substitutional solutions. Additionally, a comparison of these results to the extrapolation model of Chou is given. PMID:23814314

  4. Structural and electronic properties of Sn overlayers and {Pd}/{Sn} surface alloys on Pd(111)

    NASA Astrophysics Data System (ADS)

    Lee, Adam F.; Baddeley, Christopher J.; Tikhov, Mintcho S.; Lambert, Richard M.

    1997-03-01

    The first two layers of Sn deposited on Pd(111) at 300 K grow in layer-by-layer fashion after which crystallite formation commences. The electronic properties of these overlayers are dependent on the size of the 3D Sn islands. The occurrence of Sn→Pd valence charge-transfer is inferred, due allowance being made for initial and final state effects in the photoemission data. Evidence is presented for a significant Pd surface core-level shift enhancement by Sn of ≈0.7 eV. Depending on the initial Sn loading, heating generates stable monolayer (Pd 2Sn) or multilayer (Pd 3Sn) surface alloys exhibiting √3 and (2 × 2) periodicities, respectively. The very different CO adsorption capacity of these two phases indicates that on {Pd}/{Sn} alloy surfaces, only pure Pd threefold hollow-sites are capable of strongly chemisorbing CO.

  5. Diversity of gamma-ray burst energetics vs. supernova homogeneity: SN 2013cq associated with GRB 130427A

    NASA Astrophysics Data System (ADS)

    Melandri, A.; Pian, E.; D'Elia, V.; D'Avanzo, P.; Della Valle, M.; Mazzali, P. A.; Tagliaferri, G.; Cano, Z.; Levan, A. J.; Møoller, P.; Amati, L.; Bernardini, M. G.; Bersier, D.; Bufano, F.; Campana, S.; Castro-Tirado, A. J.; Covino, S.; Ghirlanda, G.; Hurley, K.; Malesani, D.; Masetti, N.; Palazzi, E.; Piranomonte, S.; Rossi, A.; Salvaterra, R.; Starling, R. L. C.; Tanaka, M.; Tanvir, N. R.; Vergani, S. D.

    2014-07-01

    Aims: Long-duration gamma-ray bursts (GRBs) have been found to be associated with broad-lined type-Ic supernovae (SNe), but only a handful of cases have been studied in detail. Prompted by the discovery of the exceptionally bright, nearby GRB 130427A (redshift z = 0.3399), we aim at characterising the properties of its associated SN 2013cq. This is the first opportunity to test the progenitors of high-luminosity GRBs directly. Methods: We monitored the field of the Swift long-duration GRB 130427A using the 3.6 m TNG and the 8.2 m VLT during the time interval between 3.6 and 51.6 days after the burst. Photometric and spectroscopic observations revealed the presence of the type Ic SN 2013cq. Results: Spectroscopic analysis suggests that SN 2013cq resembles two previous GRB-SNe, SN 1998bw and SN 2010bh, associated with GRB 980425 and X-ray flash (XRF) 100316D, respectively. The bolometric light curve of SN 2013cq, which is significantly affected by the host galaxy contribution, is systematically more luminous than that of SN 2010bh (~2 mag at peak), but is consistent with SN 1998bw. The comparison with the light curve model of another GRB-connected SN 2003dh indicates that SN 2013cq is consistent with the model when brightened by 20%. This suggests a synthesised radioactive 56Ni mass of ~0.4M⊙. GRB 130427A/SN 2013cq is the first case of low-z GRB-SN connection where the GRB energetics are extreme (Eγ,iso ~ 1054 erg). We show that the maximum luminosities attained by SNe associated with GRBs span a very narrow range, but those associated with XRFs are significantly less luminous. On the other hand the isotropic energies of the accompanying GRBs span 6 orders of magnitude (1048 erg SN energy budget. Based on observations made with the VLT, operated on the mountain of Cerro Paranal in Chile under programme 091.D-0291

  6. Metal stable isotope signatures as tracers in environmental geochemistry.

    PubMed

    Wiederhold, Jan G

    2015-03-01

    The biogeochemical cycling of metals in natural systems is often accompanied by stable isotope fractionation which can now be measured due to recent analytical advances. In consequence, a new research field has emerged over the last two decades, complementing the traditional stable isotope systems (H, C, O, N, S) with many more elements across the periodic table (Li, B, Mg, Si, Cl, Ca, Ti, V, Cr, Fe, Ni, Cu, Zn, Ge, Se, Br, Sr, Mo, Ag, Cd, Sn, Sb, Te, Ba, W, Pt, Hg, Tl, U) which are being explored and potentially applicable as novel geochemical tracers. This review presents the application of metal stable isotopes as source and process tracers in environmental studies, in particular by using mixing and Rayleigh model approaches. The most important concepts of mass-dependent and mass-independent metal stable isotope fractionation are introduced, and the extent of natural isotopic variations for different elements is compared. A particular focus lies on a discussion of processes (redox transformations, complexation, sorption, precipitation, dissolution, evaporation, diffusion, biological cycling) which are able to induce metal stable isotope fractionation in environmental systems. Additionally, the usefulness and limitations of metal stable isotope signatures as tracers in environmental geochemistry are discussed and future perspectives presented.

  7. Metal stable isotope signatures as tracers in environmental geochemistry.

    PubMed

    Wiederhold, Jan G

    2015-03-01

    The biogeochemical cycling of metals in natural systems is often accompanied by stable isotope fractionation which can now be measured due to recent analytical advances. In consequence, a new research field has emerged over the last two decades, complementing the traditional stable isotope systems (H, C, O, N, S) with many more elements across the periodic table (Li, B, Mg, Si, Cl, Ca, Ti, V, Cr, Fe, Ni, Cu, Zn, Ge, Se, Br, Sr, Mo, Ag, Cd, Sn, Sb, Te, Ba, W, Pt, Hg, Tl, U) which are being explored and potentially applicable as novel geochemical tracers. This review presents the application of metal stable isotopes as source and process tracers in environmental studies, in particular by using mixing and Rayleigh model approaches. The most important concepts of mass-dependent and mass-independent metal stable isotope fractionation are introduced, and the extent of natural isotopic variations for different elements is compared. A particular focus lies on a discussion of processes (redox transformations, complexation, sorption, precipitation, dissolution, evaporation, diffusion, biological cycling) which are able to induce metal stable isotope fractionation in environmental systems. Additionally, the usefulness and limitations of metal stable isotope signatures as tracers in environmental geochemistry are discussed and future perspectives presented. PMID:25640608

  8. Electrodeposition of nanostructured Sn-Zn coatings

    NASA Astrophysics Data System (ADS)

    Salhi, Y.; Cherrouf, S.; Cherkaoui, M.; Abdelouahdi, K.

    2016-03-01

    The electrodeposition of Sn-Zn coating at ambient temperature was investigated. The bath consists of metal salts SnCl2·2H2O and ZnSO4·7H2O and sodium citrate (NaC6H5Na3O7·2H2O) as complexing agent. To prevent precipitation, the pH is fixed at 5. Reducing tin and zinc through Sncit2- and ZnHcit- complex respectively is confirmed by the presence of two cathodic peaks on the voltammogram. The kinetic of tin (II) reduction process is limited by the SnCit2- dissociation. The SEM and TEM observations have showed that the coating consists of a uniform Sn-Zn layer composed of fine grains on which tin aggregates grow up. XRD revealed peaks corresponding to the hexagonal Zn phase and the tetragonal β-Sn phase.

  9. SN Refsdal: Photometry and Time Delay Measurements of the First Einstein Cross Supernova

    NASA Astrophysics Data System (ADS)

    Rodney, S. A.; Strolger, L.-G.; Kelly, P. L.; Bradač, M.; Brammer, G.; Filippenko, A. V.; Foley, R. J.; Graur, O.; Hjorth, J.; Jha, S. W.; McCully, C.; Molino, A.; Riess, A. G.; Schmidt, K. B.; Selsing, J.; Sharon, K.; Treu, T.; Weiner, B. J.; Zitrin, A.

    2016-03-01

    We present the first year of Hubble Space Telescope imaging of the unique supernova (SN) “Refsdal,” a gravitationally lensed SN at z = 1.488 ± 0.001 with multiple images behind the galaxy cluster MACS J1149.6+2223. The first four observed images of SN Refsdal (images S1-S4) exhibited a slow rise (over ˜150 days) to reach a broad peak brightness around 2015 April 20. Using a set of light curve templates constructed from SN 1987A-like peculiar Type II SNe, we measure time delays for the four images relative to S1 of 4 ± 4 (for S2), 2 ± 5 (S3), and 24 ± 7 days (S4). The measured magnification ratios relative to S1 are 1.15 ± 0.05 (S2), 1.01 ± 0.04 (S3), and 0.34 ± 0.02 (S4). None of the template light curves fully captures the photometric behavior of SN Refsdal, so we also derive complementary measurements for these parameters using polynomials to represent the intrinsic light curve shape. These more flexible fits deliver fully consistent time delays of 7 ± 2 (S2), 0.6 ± 3 (S3), and 27 ± 8 days (S4). The lensing magnification ratios are similarly consistent, measured as 1.17 ± 0.02 (S2), 1.00 ± 0.01 (S3), and 0.38 ± 0.02 (S4). We compare these measurements against published predictions from lens models, and find that the majority of model predictions are in very good agreement with our measurements. Finally, we discuss avenues for future improvement of time delay measurements—both for SN Refsdal and for other strongly lensed SNe yet to come.

  10. NEUTRON-POOR NICKEL ISOTOPE ANOMALIES IN METEORITES

    SciTech Connect

    Steele, Robert C. J.; Coath, Christopher D.; Regelous, Marcel; Elliott, Tim; Russell, Sara

    2012-10-10

    transition elements which invoked variable contributions of a neutron-rich component. We have examined different nucleosynthetic environments to determine the possible source of the anomalous material responsible for the isotopic variations observed in Ni and other transition elements within bulk samples. We find that the Ni isotopic variability of the solar system cannot be explained by mixing with a component of bulk stellar ejecta from either SN II, Wolf-Rayet or, an asymptotic giant branch source and is unlikely to result from bulk mixing of material from an SN Ia. However, variable admixture of material from the Si/S zone of an SN II can create all the characteristics of Ni isotope variations in solar system materials. Moreover, these characteristics can also be provided by an SN II with a range of masses from 15 to 40 M{sub Sun }, showing that input from SN II is a robust source for Ni isotope variations in the solar system. Correlations of Ni isotope anomalies with O, Cr, and Ti isotope ratios and Pb/Yb in bulk meteorites suggest that the heterogeneous distribution of isotopic anomalies in the early solar system likely resulted from nebular sorting of chemically or physically different materials bearing different amounts of isotopes synthesized proximally to the collapse of the protosolar nebula.

  11. Interfacial stability of SnO2/n-Si and In2O3:Sn/n-Si heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Maruska, H. P.; Ghosh, A. K.; Eustace, D. J.; Feng, T.

    1983-05-01

    High-efficiency SnO2/n-Si and In2O3:Sn/n-Si solar cells are fabricated which, when encapsulated in ethylene vinyl acetate (EVA) copolymers and kept at temperatures below 200 C, exhibit long-term stability. In the absence of proper encapsulation or at high temperatures, however, the properties of heterojunctions SnO2/n-Si and In2O3:Sn/n-Si solar cells can suffer degradation through two distinct mechanisms, one optical and the other thermal. In either case, losses in the open-circuit voltage can be correlated with changes in the dark current-voltage characteristics; light stress increases the dark saturation current, whereas heat stress lowers the diode quality fraction n. Both degradiation mechanisms are linked to changes in the stored charges in the SiOx interphase region between the conducting oxide and the silicon. The thermal process comes into play only for temperatures above 300 C, and the optical process arises only when ultraviolet light is incident on the cell.

  12. EARLY-PHASE PHOTOMETRY AND SPECTROSCOPY OF TRANSITIONAL TYPE Ia SN 2012ht: DIRECT CONSTRAINT ON THE RISE TIME

    SciTech Connect

    Yamanaka, Masayuki; Nogami, Daisaku; Maeda, Keiichi; Kawabata, Miho; Masumoto, Kazunari; Matsumoto, Katsura; Tanaka, Masaomi; Takaki, Katsutoshi; Ueno, Issei; Itoh, Ryosuke; Kawabata, Koji S.; Moritani, Yuki; Akitaya, Hiroshi; Yoshida, Michitoshi; Arai, Akira; Honda, Satoshi; Nishiyama, Koichi; Kabashima, Fujio

    2014-02-20

    We report photometric and spectroscopic observations of the nearby Type Ia Supernova (SN Ia) 2012ht from –15.8 days to +49.1 days after B-band maximum. The decline rate of the light curve is Δm {sub 15}(B) = 1.39 ± 0.05 mag, which is intermediate between normal and subluminous SNe Ia, and similar to that of the ''transitional'' Type Ia SN 2004eo. The spectral line profiles also closely resemble those of SN 2004eo. We were able to observe SN 2012ht at a very early phase, when it was still rising and was about three magnitudes fainter than at the peak. The rise time to the B-band maximum is estimated to be 17.6 ± 0.5 days and the time of the explosion is MJD 56277.98 ± 0.13. SN 2012ht is the first transitional SN Ia whose rise time is directly measured without using light curve templates, and the fifth SN Ia overall. This rise time is consistent with those of the other four SNe within the measurement error, even including the extremely early detection of SN 2013dy. The rising part of the light curve can be fitted by a quadratic function, and shows no sign of a shock-heating component due to the interaction of the ejecta with a companion star. The rise time is significantly longer than that inferred for subluminous SNe such as SN 1991bg, which suggests that a progenitor and/or explosion mechanism of transitional SNe Ia are more similar to normal SNe Ia rather than to subluminous SNe Ia.

  13. Optical and infrared observations of the TypeIIP SN2002hh from days 3 to 397

    NASA Astrophysics Data System (ADS)

    Pozzo, M.; Meikle, W. P. S.; Rayner, J. T.; Joseph, R. D.; Filippenko, A. V.; Foley, R. J.; Li, W.; Mattila, S.; Sollerman, J.

    2006-05-01

    We present optical and infrared (IR) observations of the TypeII SN2002hh from 3 to 397d after explosion. The optical spectroscopic (4-397d) and photometric (3-278d) data are complemented by spectroscopic (137-381d) and photometric (137-314d) data acquired at IR wavelengths. This is the first time L-band spectra have ever been successfully obtained for a supernova (SN) at a distance beyond the Local Group. The VRI light curves in the first 40d reveal SN2002hh to be an SNIIP (plateau) - the most common of all core-collapse SNe. SN2002hh is one of the most highly extinguished SNe ever investigated. To provide a match between its early-time spectrum and a coeval spectrum of the TypeIIP SN1999em, as well as maintaining consistency with KI interstellar absorption, we invoke a two-component extinction model. One component is due to the combined effect of the interstellar medium (ISM) of our Milky Way Galaxy and the SN host galaxy, while the other component is due to a `dust pocket' where the grains have a mean size smaller than in the ISM. The early-time optical light curves of SNe1999em and 2002hh are generally well matched, as are the radioactive tails of these two SNe and SN1987A. The late-time similarity of the SN2002hh optical light curves to those of SN1987A, together with measurements of the optical/IR luminosity and [FeII]1.257μm emission indicate that 0.07 +/- 0.02Msolar of 56Ni was ejected by SN2002hh. However, during the nebular phase the HKL' luminosities of SN2002hh exhibit a growing excess with respect to those of SN1987A. We attribute much of this excess to an IR-echo from a pre-existing, dusty circumstellar medium. Based on an IR-echo interpretation of the near-IR (NIR) excess, we deduce that the progenitor of SN2002hh underwent recent mass-loss of ~0.3Msolar. A detailed comparison of the late-time optical and NIR spectra of SNe1987A and 2002hh is presented. While the overall impression is one of similarity between the spectra of the two events, there are

  14. Photovoltaic performance of hybrid ITO/PEDOT:PSS/n-SnS/Al solar cell structure

    NASA Astrophysics Data System (ADS)

    Jain, Priyal; Arun, P.

    2016-07-01

    The present paper discusses the performance of ITO/PEDOT:PSS/n-SnS/Al structured solar cells fabricated by thermal evaporation. The performance characterizing parameters such as the open circuit voltage, short circuit current density, series resistance, parallel resistance, ideality factor and the overall efficiency were found to be dependent on the SnS grain size in the nano-meter regime and incident light intensity. The experimental work directly reconfirms the theoretical results and ideas raised in the literature by early researchers.

  15. Seawater sulfur isotope fluctuations in the Cretaceous.

    PubMed

    Paytan, Adina; Kastner, Miriam; Campbell, Douglas; Thiemens, Mark H

    2004-06-11

    The exogenic sulfur cycle is tightly coupled with the carbon and oxygen cycles, and therefore a central component of Earth's biogeochemistry. Here we present a high-resolution record of the sulfur isotopic composition of seawater sulfate for the Cretaceous. The general enrichment of isotopically light sulfur that prevailed during the Cretaceous may have been due to increased volcanic and hydrothermal activity. Two excursions toward isotopically lighter sulfur represent periods of lower rates of pyrite burial, implying a shift in the location of organic carbon burial to terrestrial or open-ocean settings. The concurrent changes in seawater sulfur and inorganic carbon isotopic compositions imply short-term variability in atmospheric oxygen partial pressure.

  16. Direct observation of Sn crystal growth during the lithiation and delithiation processes of SnO(2) nanowires.

    PubMed

    Zhang, Li Qiang; Liu, Xiao Hua; Perng, Ya-Chuan; Cho, Jea; Chang, Jane P; Mao, Scott X; Ye, Zhi Zhen; Huang, Jian Yu

    2012-11-01

    Tin (Sn) crystal growth on Sn-based anodes in lithium ion batteries is hazardous for reasons such as possible short-circuit failure by Sn whiskers and Sn-catalyzed electrolyte decomposition, but the growth mechanism of Sn crystals during battery cycling is not clear. Here we report different growth mechanisms of Sn crystal during the lithiation and delithiation processes of SnO(2) nanowires revealed by in situ transmission electron microscopy (TEM). Large spherical Sn nanoparticles with sizes of 20-200nm grew instantaneously upon lithiation of a single-crystalline SnO(2) nanowire at large current density (j>20A/cm(2)), which suppressed formation of the Li(x)Sn alloy but promoted agglomeration of Sn atoms. Control experiments of Joule-heating (j≈2400A/cm(2)) the pristine SnO(2) nanowires resulted in melting of the SnO(2) nanowires but not Sn particle growth, indicating that the abnormal Sn particle growth was induced by both chemical reduction (i.e., breaking the SnO(2) lattice to produce Sn atoms) and agglomeration of the Sn atoms assisted by Joule heating. Intriguingly, Sn crystals grew out of the nanowire surface via a different "squeeze-out" mechanism during delithiation of the lithiated SnO(2) nanowires coated with an ultra-thin solid electrolyte LiAlSiO(x) layer. It is attributed to the negative stress gradient generated by the fast Li extraction in the surface region through the Li(+)-conducting LiAlSiO(x) layer. Our previous studies showed that Sn precipitation does not occur in the carbon-coated SnO(2) nanowires, highlighting the effect of nanoengineering on tailoring the electrochemical reaction kinetics to suppress the hazardous Sn whiskers or nanoparticles formation in a lithium ion battery. PMID:22770619

  17. Bili lights

    MedlinePlus

    Phototherapy for jaundice; Bilirubin - bili lights; Neonatal care - bili lights; Newborn care - bili lights ... Phototherapy involves shining fluorescent light from the bili lights on bare skin. A specific wavelength of light can break down bilirubin into a form that ...

  18. Iron isotope composition of some Archean and Proterozoic iron formations

    NASA Astrophysics Data System (ADS)

    Planavsky, Noah; Rouxel, Olivier J.; Bekker, Andrey; Hofmann, Axel; Little, Crispin T. S.; Lyons, Timothy W.

    2012-03-01

    Fe isotopes can provide new insight into redox-dependent biogeochemical processes. Precambrian iron formations (IF) are deserving targets for Fe isotope studies because they are composed predominantly of authigenic Fe phases and record a period of unprecedented iron deposition in Earth's history. We present Fe isotope data for bulk samples from 24 Archean and Proterozoic IF and eight Phanerozoic Fe oxide-rich deposits. These data reveal that many Archean and early Paleoproterozoic iron formations were a sink for isotopically heavy Fe, in contrast to later Proterozoic and Phanerozoic Fe oxide-rich rocks. The positive δ56Fe values in IF are best explained by delivery of particulate ferric oxides formed in the water column to the sediment-water interface. Because IF are a net sink for isotopically heavy Fe, there must be a corresponding pool of isotopically light Fe in the sedimentary record. Earlier work suggested that Archean pyritic black shales were an important part of this light sink before 2.35 billion years ago (Ga). It is therefore likely that the persistently and anomalously low δ56Fe values in shales are linked with the deposition of isotopically heavy Fe in IF in the deeper parts of basins. IF deposition produced a residual isotopically light dissolved Fe pool that was captured by pyritic Fe in shales. Local dissimilatory Fe reduction in porewater and associated diagenetic reactions resulting in pyrite and carbonate precipitation may have further enhanced Fe isotope heterogeneity in marine sediments, and an 'iron shuttle' may have transported isotopically light Fe from shelf sediments to the basin. Nevertheless, water-column processing of hydrothermally delivered Fe likely had the strongest influence on the bulk iron isotope composition of Archean and Paleoproterozoic iron formations and other marine sediments.

  19. The earliest Lunar Magma Ocean differentiation recorded in Fe isotopes

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Jacobsen, Stein B.; Sedaghatpour, Fatemeh; Chen, Heng; Korotev, Randy L.

    2015-11-01

    Recent high-precision isotopic measurements show that the isotopic similarity of Earth and Moon is unique among all known planetary bodies in our Solar System. These observations provide fundamental constraints on the origin of Earth-Moon system, likely a catastrophic Giant Impact event. However, in contrast to the isotopic composition of many elements (e.g., O, Mg, Si, K, Ti, Cr, and W), the Fe isotopic compositions of all lunar samples are significantly different from those of the bulk silicate Earth. Such a global Fe isotopic difference between the Moon and Earth provides an important constraint on the lunar formation - such as the amount of Fe evaporation as a result of a Giant Impact origin of the Moon. Here, we show through high-precision Fe isotopic measurements of one of the oldest lunar rocks (4.51 ± 0.10 Gyr dunite 72 415), compared with Fe isotope results of other lunar samples from the Apollo program, and lunar meteorites, that the lunar dunite is enriched in light Fe isotopes, complementing the heavy Fe isotope enrichment in other lunar samples. Thus, the earliest olivine accumulation in the Lunar Magma Ocean may have been enriched in light Fe isotopes. This new observation allows the Fe isotopic composition of the bulk silicate Moon to be identical to that of the bulk silicate Earth, by balancing light Fe in the deep Moon with heavy Fe in the shallow Moon rather than the Moon having a heavier Fe isotope composition than Earth as a result of Giant Impact vaporization.

  20. Recalibrating the Sunspot Number (SN): The 3rd and 4th SN Workshops

    NASA Astrophysics Data System (ADS)

    Cliver, E. W.; Clette, F.; Svalgaard, L.; Vaquero, J. M.

    At the XIIth Hvar Astrophysical Colloquium in 2012, we reviewed the progress of an effort begun in 2011 to recalibrate the sunspot number (SN). That work is now nearing completion and we review the motivation, approach, and results of this process which was conducted via a series of four international workshops. Previously we discussed the principal results of workshops at Sunspot in 2011 and Brussels in 2012. These involved the identification of discontinuities circa 1885 in the Hoyt and Schatten Group SN and 1945 in the International SN. Subsequently, workshops were held in Tucson (2013) and Locarno (2014). Key results during the time of these two workshops included: (1) development of an independent ''backbone'' method for determining the Group sunspot number; (2) identification of post-1970 inhomogeneities in the Group SN and the International SN; (3) construction of preliminary revisions of the Group SN from 1610-present and the International SN from 1700--present; (4) reassessment (ongoing) of the Hoyt and Schatten Group SN data base from 1610-present; and (5) establishment of a SN archive at the University of Extremadura. The release of the new International and Group SN series is anticipated during the second half of 2015 and procedures are being put in place both to maintain the calibration of these two series and to produce subsequent revisions should more historical data be unearthed or new inhomogeneities in the series be uncovered or arise.

  1. Iron Isotopic Fractionation in Early Planetary Crusts

    NASA Astrophysics Data System (ADS)

    Wang, K.; Moynier, F.; Dauphas, N.; Barrat, J.; Day, J. M.; Sio, C.; Korotev, R. L.; Zeigler, R. A.

    2012-12-01

    Differentiated meteorites (achondrites) derive from planetary bodies that experienced variable degrees of melting and silicate-metal segregation. The oldest achondrites, such as eucrites, angrites, brachinites and the oligoclase-rich meteorites Graves Nunataks 06128/06129 (GRA 06128/9), were formed ~2-5 Ma after the first Solar System solids. They represent the oldest differentiated silicate samples known in the Solar System and the study of these samples provides insight on the origins and conditions of formation of the first planetary crusts. Here, we present new high-precision data for the Fe isotopic compositions of eucrites, angrites, brachinites and GRA 06128/9 and interpret these results in terms of magmatism during formation of these samples. We find that most eucrites and brachinites are not fractionated compared to undifferentiated chondritic meteorites (δ56Fe = 0.00±0.01, 2se), while the rare Stannern-trend eucrites are slightly enriched in the heavier isotopes of Fe. Angrites are also enriched in the heavier isotopes (δ56Fe = 0.12±0.01, 2se), similar to what is observed for terrestrial basalts, reflecting the relatively high oxidation states of the angrite parent body(ies). Contrastingly to the 'basaltic' achondrites, GRA 06128/9 are enriched in light isotopes of Fe (δ56Fe = -0.08±0.02, 2se). Evidence for light Fe isotope enrichments may be the consequence of the segregation of magma rich in sulphide (usually enriched in light isotopes of Fe compared to silicate and metal in undifferentiated meteorites). If correct, this result not only confirms that GRA 06128/9 represent products from <30% partial melting of an asteroidal body, prior to core formation, but also indicates complementary Fe isotope systematics between GRA 06128/9 and brachinites.

  2. High-resolution photoluminescence spectroscopy of Sn-doped ZnO single crystals

    SciTech Connect

    Kumar, E. Senthil; Mohammadbeigi, F.; Boatner, Lynn A.; Watkins, S. P.

    2016-01-01

    Here, Group IV donors in ZnO are poorly understood, despite evidence that they are effective n-dopants. We present high-resolution photoluminescence spectroscopy studies of unintentionally doped and Sn doped ZnO single crystals grown by the chemical vapor transport method. Doped samples showed greatly increased emission from the I10 bound exciton transition which was recently proven to be related to the incorporation of Sn impurities based on radio-isotope studies. PL linewidths are exceptionally sharp for these samples, enabling clear identification of several donor species. Temperature dependent PL measurements of the I10 line emission energy and intensity dependence reveal a behavior similar to other shallow donors in ZnO. Ionized donor bound exciton and two electron satellite transitions of the I10 transition are unambiguously identified and yield a donor binding energy of 71 meV. In contrast to recent reports of Ge-related donors in ZnO, the spectroscopic binding energy for the Sn-related donor bound exciton follows a linear relationship with donor binding energy (Haynes rule), confirming the shallow nature of this defect center, which we attribute to a SnZn double donor compensated by an unknown single acceptor.

  3. High-resolution photoluminescence spectroscopy of Sn-doped ZnO single crystals

    DOE PAGES

    Kumar, E. Senthil; Mohammadbeigi, F.; Boatner, Lynn A.; Watkins, S. P.

    2016-01-01

    Here, Group IV donors in ZnO are poorly understood, despite evidence that they are effective n-dopants. We present high-resolution photoluminescence spectroscopy studies of unintentionally doped and Sn doped ZnO single crystals grown by the chemical vapor transport method. Doped samples showed greatly increased emission from the I10 bound exciton transition which was recently proven to be related to the incorporation of Sn impurities based on radio-isotope studies. PL linewidths are exceptionally sharp for these samples, enabling clear identification of several donor species. Temperature dependent PL measurements of the I10 line emission energy and intensity dependence reveal a behavior similar tomore » other shallow donors in ZnO. Ionized donor bound exciton and two electron satellite transitions of the I10 transition are unambiguously identified and yield a donor binding energy of 71 meV. In contrast to recent reports of Ge-related donors in ZnO, the spectroscopic binding energy for the Sn-related donor bound exciton follows a linear relationship with donor binding energy (Haynes rule), confirming the shallow nature of this defect center, which we attribute to a SnZn double donor compensated by an unknown single acceptor.« less

  4. METHOD OF ISOTOPE CONCENTRATION

    DOEpatents

    Spevack, J.S.

    1957-04-01

    An isotope concentration process is described which consists of exchanging, at two or more different temperature stages, two isotopes of an element between substances that are physically separate from each other and each of which is capable of containing either of the isotopes, and withdrawing from a point between at least two of the temperatare stages one of the substances containing an increased concentration of the desired isotope.

  5. Axions and SN1987A

    NASA Technical Reports Server (NTRS)

    Burrows, Adam; Turner, Michael S.; Brinkmann, R. P.

    1988-01-01

    The effect of free-streaming axion emission on numerical models for the cooling of the newly born neutron star associated with SN1987A is considered. It is found that for an axion mass of greater than approximately 10 to the -3 eV, axion emission shortens the duration of the expected neutrino burst so significantly that it would be inconsistent with the neutrino observations made by the Kamiokande II and Irvine-Michigan-Brookhaven detectors. However, the possibility has not been investigated that axion trapping (which should occur for masses greater than or equal to 0.02 eV) sufficiently reduces axion emission so that axion masses greater than approximately 2 eV would be consistent with the neutrino observations.

  6. Preparation and characterization of Ni-doped ZnO-SnO2 nanocomposites: Application in photocatalysis

    NASA Astrophysics Data System (ADS)

    Ben Ali, Monaam; Barka-Bouaifel, Fatiha; Sieber, Brigitte; Elhouichet, Habib; Addad, Ahmed; Boussekey, Luc; Férid, Mokhtar; Boukherroub, Rabah

    2016-03-01

    The paper reports on the synthesis of nickel-doped ZnO-SnO2 nanocomposites with a molar ratio Zn:Sn of 2:1 using the hydrothermal method followed by calcination at 700 °C. The resulting nanocomposites were characterized using X-ray diffraction (XRD) patterns, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and Energy-dispersive X-ray spectroscopy (EDX). The results revealed that the Ni/ZnO-SnO2 material consists of aggregated cassiterite SnO2 and wurtzite ZnO nanoparticles (NPs) with a size ranging from 14 to 40 nm. Furthermore, they show that Ni adding induces a dominant effect on the optical, structural and morphological properties of ZnO-SnO2 NPs. The photocatalytic behavior of the synthesized nanocomposites is investigated using rhodamine B (RhB) as model organic pollutant. A maximum degradation efficiency of 96% is achieved under visible light irradiation. While nickel doping did not enhance the photocatalytic activity of ZnO-SnO2 NPs, the photocatalytic performance of Ni/ZnO-SnO2 NPs is much higher than that of Ni-doped ZnO NPs. The photodegradation mechanism is believed to occur through photosensitization.

  7. SN 1987A: Chandra Witnesses the End of an Era

    NASA Astrophysics Data System (ADS)

    Frank, Kari A.; Burrows, David N.

    2016-04-01

    Due to its age and close proximity, the remnant of SN 1987A is the only supernova remnant in which we can study the early developmental stages in detail, providing insight into stellar evolution, the mechanisms of the supernova explosion, and the transition from supernova to supernova remnant as the debris begins to interact with the surrounding circumstellar medium (CSM). We present the latest results from 16 years of Chandra ACIS observations of SN 1987A, now covering 4600 - 10500 days after the supernova. At approximately day 7500, the east-west asymmetry of the ring began to reverse, while the spectra and soft X-ray light curve revealed that the increase in soft X-ray emission slowed dramatically. This suggests the average CSM density encountered by the blast wave decreased at this time, likely due to lack of new emission from the densest clumps in the equatorial ring. Since day 9700 the soft X-ray light curve has flattened and remained approximately constant, evidence that the blast wave has now left the dense material of the known equatorial ring and is beginning to probe the unknown territory beyond.

  8. Nanocrystalline sol-gel TiO{sub 2}-SnO{sub 2} coatings: Preparation, characterization and photo-catalytic performance

    SciTech Connect

    Kaleji, Behzad Koozegar; Sarraf-Mamoory, Rasoul

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer SnO{sub 2} additive enhanced significantly photo-catalytic properties of TiO{sub 2} based thin film for remove of organic compounds. Black-Right-Pointing-Pointer Structural and optical properties are dependent on dopant concentration. Black-Right-Pointing-Pointer TiO{sub 2}-SnO{sub 2} nanocrystalline thin film is promising for photocatalytic properties in visible light. -- Abstract: In this study, preparation of SnO{sub 2} (0-30 mol% SnO{sub 2})-TiO{sub 2} dip-coated thin films on glazed porcelain substrates via sol-gel process has been investigated. The effects of SnO{sub 2} on the structural, optical, and photo-catalytic properties of applied thin films have been studied by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Surface topography and surface chemical state of thin films were examined by atomic force microscopy and X-ray photoelectron spectroscopy. XRD patterns showed an increase in peak intensities of the rutile crystalline phase by increasing the SnO{sub 2} content. The prepared Sn doped TiO{sub 2} photo-catalyst films showed optical absorption in the visible light area exhibited excellent photo-catalytic ability for the degradation of methylene blue under visible light irradiation. Best photo-catalytic activity of Sn doped TiO{sub 2} thin films was measured in the TiO{sub 2}-15 mol% SnO{sub 2} sample by the Sn{sup 4+} dopants presented substitution Ti{sup 4+} into the lattice of TiO{sub 2} increasing the surface oxygen vacancies and the surface hydroxyl groups.

  9. Statistical clumped isotope signatures.

    PubMed

    Röckmann, T; Popa, M E; Krol, M C; Hofmann, M E G

    2016-08-18

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules.

  10. Statistical clumped isotope signatures

    PubMed Central

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  11. Statistical clumped isotope signatures

    NASA Astrophysics Data System (ADS)

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-08-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules.

  12. Statistical clumped isotope signatures.

    PubMed

    Röckmann, T; Popa, M E; Krol, M C; Hofmann, M E G

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  13. Cosmic ray isotopes

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1973-01-01

    The isotopic composition of cosmic rays is studied in order to develop the relationship between cosmic rays and stellar processes. Cross section and model calculations are reported on isotopes of H, He, Be, Al and Fe. Satellite instrument measuring techniques separate only the isotopes of the lighter elements.

  14. SN 2013ej IN M74: A LUMINOUS AND FAST-DECLINING TYPE II-P SUPERNOVA

    SciTech Connect

    Huang, Fang; Wang, Xiaofeng; Chen, Juncheng; Mo, Jun; Zhao, Xulin; Zhang, Jujia; Brown, Peter J.; Zampieri, Luca; Pumo, Maria Letizia; Zhang, Tianmeng E-mail: wang_xf@mail.tsinghua.edu.cn

    2015-07-01

    We present extensive ultraviolet, optical, and near-infrared observations of the Type IIP supernova (SN IIP) 2013ej in the nearby spiral galaxy M74. The multicolor light curves, spanning from ∼8–185 days after explosion, show that it has a higher peak luminosity (i.e., M{sub V} ∼ −17.83 mag at maximum light), a faster post-peak decline, and a shorter plateau phase (i.e., ∼50 days) compared to the normal Type IIP SN 1999em. The mass of {sup 56}Ni is estimated as 0.02 ± 0.01 M{sub ⊙} from the radioactive tail of the bolometric light curve. The spectral evolution of SN 2013ej is similar to that of SN 2004et and SN 2007od, but shows a larger expansion velocity (i.e., v{sub Fe} {sub ii} ∼ 4600 km s{sup −1} at t ∼ 50 days) and broader line profiles. In the nebular phase, the emission of the Hα line displays a double-peak structure, perhaps due to the asymmetric distribution of {sup 56}Ni produced in the explosion. With the constraints from the main observables such as bolometric light curve, expansion velocity, and photospheric temperature of SN 2013ej, we performed hydrodynamical simulations of the explosion parameters, yielding the total explosion energy as ∼0.7× 10{sup 51} erg, the radius of the progenitor as ∼600 R{sub ⊙}, and the ejected mass as ∼10.6 M{sub ⊙}. These results suggest that SN 2013ej likely arose from a red supergiant with a mass of 12–13 M{sub ⊙} immediately before the explosion.

  15. Delayed neutrons in fission of polonium isotopes

    SciTech Connect

    Ramazanov, R.; Urikbaev, Z.S.; Maksyutenko, B.P.; Ignat'ev, S.V.

    1988-06-01

    A strong difference is found in the relative yields of delayed neutrons in the production of compound nuclei of polonium isotopes in reactions in which bismuth and lead are bombarded by various charged particles. The effect can be partially explained by the different lengths of the ..beta..-decay chains of the light and heavy fission products.

  16. Light echoes - Type II supernovae

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.

    1987-01-01

    Type II supernovae (SNs) light curves show a remarkable range of shapes. Data have been collected for the 12 Type II SNs that have light curve information for more than four months past maximum. Contrary to previous reports, it is found that (1) the decay rate after 100 days past maximum varies by almost an order of magnitude and (2) the light curve shapes are not bimodally distributed, but actually form a continuum. In addition, it is found that the extinctions to the SNs are related to the light curve shapes. This implies that the absorbing dust is local to the SNs. The dust is likely to be part of a circumstellar shell emitted by the SN progenitor that Dwek (1983) has used to explain infrared echoes. The optical depth of the shell can get quite large. In such cases, it is found that the photons scattered and delayed by reflection off dust grains will dominate the light curve several months after peak brightness. This 'light echo' offers a straightforward explanation of the diversity of Type II SN light curves.

  17. Magnetic properties of the intermetallic compounds PrNiSn and NdNiSn

    NASA Astrophysics Data System (ADS)

    Beirne, Eamonn Daniel

    Inelastic neutron scattering has been used to determine the crystalline electric field (CEF) excitations in the intermetallic compound PrNiSn. Polycrystalline samples of PiNiSn are found to have 7 excitations up to 30 meV, with strong low-lying modes at 2.0, 3.5, and 5.1 meV. The site symmetry of Pr3+ in this system is such that the degeneracy of the 9 levels in the J = 4 ground state multiplet is removed completely by the crystal field. From fitting this data, it is clear that the ground state is a singlet that couples to each of the other 8 excited states. The wavefunctions of the levels are determined and a level scheme proposed for this material. Inelastic scattering results are also presented for a single crystal of PrNiSn. The dispersion of the low-lying E = 3.5 meV CEF excitation is documented, showing 4 distinct modes corresponding to the 4 Pr ions in the unit cell. Susceptibility and magnetisation results for PrNiSn and NdNiSn are presented. From these measurements it is clear that the PrNiSn does not order magnetically down to 2K, whereas NdNiSn has an antifenomagnetic transition at TN = 3.1K. Resistivity measurements on PrNiSn also show no evidence of a magnetic transition, but there are gradient changes at around 4.5K and 12K. This corresponds to a local maximum at 12K and local minimum at 4.5K along the b-axis in this compound. Measurements on single crystals of these compounds show strong anisotropy in both cases, attributed to CEF effects. From the proposed CEF level scheme, the bulk properties such as the susceptibility can be modelled. Neutron powder diffraction measurements on both PrNiSn and NdNiSn confirm that there is no magnetic transition down to 1.6K in PrNiSn, and TN is confirmed for NdNiSn. Structural Rietveld fitting confirms the room temperature orthorhombic structure in both systems down to low temperature, but the magnetic structure of NdNiSn can not be determined. This is due to the magnetic peaks below TN doubling up, indicating a

  18. Radio Observations of SN 1979C: Evidence for Rapid Presupernova Evolution

    NASA Astrophysics Data System (ADS)

    Montes, Marcos J.; Weiler, Kurt W.; Van Dyk, Schuyler D.; Panagia, Nino; Lacey, Christina K.; Sramek, Richard A.; Park, Richard

    2000-04-01

    We present new radio observations of the supernova SN 1979C made with the Very Large Array (VLA) at 20, 6, 3.6, and 2 cm from 1991 July to 1998 October, which extend our previously published observations (Weiler et al.), which began 8 days after optical maximum in 1979 April and continued through 1990 December. We find that the radio emission from SN 1979C has stopped declining in flux density in the manner described by Weiler et al. and has apparently entered a new stage of evolution. The observed ``flattening,'' or possible brightening, of the radio light curves for SN 1979C is interpreted as due to the supernova shock wave entering a denser region of material near the progenitor star and may be indicative of complex structure in the circumstellar medium established by the stellar wind from the red supergiant (RSG) progenitor.

  19. Efficient thermolysis route to monodisperse Cu₂ZnSnS₄ nanocrystals with controlled shape and structure.

    PubMed

    Zhang, Xiaoyan; Guo, Guobiao; Ji, Cheng; Huang, Kai; Zha, Chenyang; Wang, Yifeng; Shen, Liming; Gupta, Arunava; Bao, Ningzhong

    2014-01-01

    Monodisperse Cu2ZnSnS4 (CZTS) nanocrystals with tunable shape, crystalline phase, and composition are synthesized by efficient thermolysis of a single source precursor of mixed metal-oleate complexes in hot organic solvents with dissolved sulfur sources. Suitable tuning of the synthetic conditions and the Cu/(Zn + Sn) ratio of the precursor has enabled precise control of the crystalline phase in the form of kesterite, or a newly observed wurtzite structure. Nanocrystals with morphology in the form of spherical, rice-like, or rod-like shapes are obtained over a wide range of compositions (0.5 ≤ Cu/(Zn + Sn) ≤ 1.2). Both the final products and intermediates for each shape exhibit consistent composition and structure, indicating homogenous nucleation and growth of single-phase nanocrystals. Thin films prepared from colloidal nanocrystal suspensions display interesting shape-dependent photoresponse behavior under white light illumination from a solar simulator. PMID:24866987

  20. Sn Attenuation in the Middle-East

    NASA Astrophysics Data System (ADS)

    Ku, W.; Kaviani, A.; Bao, X.; Sandvol, E. A.

    2015-12-01

    The Turkish-Iranian Plateau and Zagros Mountains, a dominant tectonic feature in the Middle-East, were formed as a result of the continental collision (between Arabian plate and Eurasia plates). In order to better understand the nature of the lithosphere mantle and origin of the measure seismic velocity anomalies we have made detailed measurements of the uppermost mantle attenuation using the high frequency regional phase Sn. In order to measure Sn attenuation. We have collected a large data set consisting of 18 years (1995-2012) of waveforms recorded by 305 permanent and temporary stations. We used a bandpass filter (0.1-0.5Hz) to identify efficient longer period Sn phases. In order to determine Sn Q we applied a Two Station Method (TSM) and Reverse Two Station Method (RTM) to eliminate the source effects. We have used the LSQR algorithm to tomographically map Sn attenuation tomography across the Middle-East. We also determined the Sn propagation efficiencies visually and tomographically map qualitatively assigned Sn propagation efficiencies across the Middle-East. The Sn Attenuation Tomography show moderately low Q values beneath the Turkish-Iranian Plateau (~250) and high Q values beneath the south Caspian sea (~400) and Arabian shield (~400). We also observe high Q values beneath the Zagros mountains (~450) that is consistent with the Arabian plate underthrusting beneath the Eurasia plate. The Sn Efficiency Tomography shows high attenuation within the Turkish-Iranian Plateau and low attenuation in the Arabian Plate and across the Caspian Sea. This is consistent with prior studies that suggest a hot and thin lithosphere beneath the Turkish-Iranian Plateau and it also suggests that intrinsic attenuation is the dominant component in Sn Q across the Turkish-Iranian Plateau. Due to the signal-to-noise criterion to select amplitudes and the efficiency criterion to select two-station and reverse-two-station paths for the inversion, the data are left-censored and the

  1. JVLA observations of SN2013bv

    NASA Astrophysics Data System (ADS)

    Kamble, Atish; Soderberg, Alicia

    2013-05-01

    We report radio observations with the Jansky Very Large Array of the Type Ic supernova SN2013bv discovered by Zhang et al.(CBET #3499) on April 9.51 UT and spectroscopically classified as broad-lined supernova similar to SN1998bw by Silverman et al. (CBET #3499). On 2013 April 27.0 UT, we triggered VLA observations at the position of SN2013bv at 4.8 & 7.1 GHz. No radio emission is detected in either of the frequency bands at the position of the supernova down to 3-sigma RMS level of 7 microJy.

  2. SN IA in the IR: RAISIN A progress report

    NASA Astrophysics Data System (ADS)

    Kirshner, Robert P.; The RAISIN TEAM

    2014-01-01

    SN Ia have proven to be a powerful tool for cosmology. Near-IR observations of SN Ia promise even better results because the supernovae are more nearly standard candles at those wavelengths and absorption by dust is diminished by a factor of 4 compared to rest-frame B-band observations. Near IR observations of cosmologically-distant SN Ia discovered with PanSTARRS are underway using the infrared camera on the Hubble Space Telescope (GO-13046). These targets are discovered in the difference images created in the CfA/JHU pipeline, confirmed spectroscopically at the MMT, Magellan, Gemini, or Keck, and inserted in a non-disruptive way into the HST observing schedule for WFC3-IR. We have observed over 20 SN Ia in the range 0.2 < z < 0.5 during Cycle 21 and this is a progress report on the analysis. The final results require a repeat observation after the supernova has faded. Those will be completed in 2014, but we have a sufficient sample of objects for which the supernova is well separated from the host galaxy to illustrate the power of this technique. Preliminary analysis shows HST data can reduce the uncertainty in the distance to each supernova by a factor or 2. Sufficiently large supernova samples have been gathered at all redshifts so that statistical errors in interesting parameters (like the dark energy equation-of-state index (1 +w)), have been driven down to the same level as the systematic errors (about 7%). Further progress is limited by our ability to master the systematic errors. These include the correction for luminosity based on the light curve shape and the correction based on intrinsic color and reddening by dust. Since SN IA behave better in the IR in both these ways, there is reason to expect that this approach will be effective in driving down the systematic errors over time. If we are diligent in building up the size of the sample that is observed in the rest-frame infrared, we can expect more certain knowledge of the properties of dark energy

  3. The peculiar case of the “double-humped" super-luminous supernova SN 2006oz

    NASA Astrophysics Data System (ADS)

    Ouyed, Rachid; Leahy, Denis

    2013-10-01

    SN 2006oz is a super-luminous supernova with a mysterious bright precursor that has resisted explanation in standard models. However, such a precursor has been predicted in the dual-shock quark nova model of super-luminous supernovae — the precursor is the supernova event while the main light curve of the super-luminous supernova is powered by the Quark-Nova (explosive transition of the neutron star to a quark star). As the supernova is fading, the Quark-Nova re-energizes the supernova ejecta, producing a “double-humped" light curve. We show that the quark nova model successfully reproduces the observed light curve of SN 2006oz.

  4. Nano-needle structured, ambipolar high electrical conductivity SnOx (x ≤ 1) thin films for infrared optoelectronics

    NASA Astrophysics Data System (ADS)

    Wong, Andrew; Wang, Xiaoxin; Liu, Jifeng

    2015-03-01

    SnO has become an important earth-abundant transparent conductive oxide (TCO) with applications not only in photovoltaics but also in electrodes for energy storage. For optoelectronic applications, low fabrication temperature, high electrical conductivity, and low optical losses are highly desirable. This study presents self-assembled, ambipolar (i.e., n and p-type) nano-needle structured SnOx (x ≤ 1) thin films with high electrical conductivity, low infrared (IR) optical losses, and potentials for effective light trapping. These nano-needle structured SnOx films are fabricated through non-reactive co-sputtering of Sn and SnO2 followed by crystallization annealing at low temperatures <250 °C. The crystallization of SnOx thin films occurred rapidly above 210 °C, resulting in SnO nano-needles with average dimensions of 1 μm long, 0.1 μm wide, and 0.15 μm thick that are interspersed with Sn nanocrystals. The optical scattering from these nanostructures can be utilized for light trapping in thin film absorbers. We also found that laser pre-patterning enabled control over nano-needle crystal size and growth directions. The electrical conductivity of 1500-2000 S/cm is comparable to state-of-the-art SnO2:F TCOs while the fabrication temperature is reduced by ˜200 °C, enabling a broader range of applications, such as optoelectronics on flexible substrates. Hall effect measurements show an intriguing ambipolar behavior depending on the annealing ambient. Especially, a strong p-type conductivity with a hole concentration of p ˜ 5 × 1021 cm-3 and mobility μp ˜ 2 cm2 V-1 s-1 is obtained in a weak oxidizing ambient. Such a high p-type conductivity is particularly rare in TCOs, and it offers potential applications in bipolar oxide semiconductor devices. Optical measurements showed a low absorption loss of <3% in a broad IR wavelength regime of λ = 1100-2500 nm for p-type SnOx, suggesting that these nano-needle structured SnOx TCOs can be engineered to enhance low

  5. AgI alloying in SnTe boosts the thermoelectric performance via simultaneous valence band convergence and carrier concentration optimization

    NASA Astrophysics Data System (ADS)

    Banik, Ananya; Biswas, Kanishka

    2016-10-01

    SnTe, a Pb-free analogue of PbTe, was earlier assumed to be a poor thermoelectric material due to excess p-type carrier concentration and large energy separation between light and heavy hole valence bands. Here, we report the enhancement of the thermoelectric performance of p-type SnTe by Ag and I co-doping. AgI (1-6 mol%) alloying in SnTe modulates its electronic structure by increasing the band gap of SnTe, which results in decrease in the energy separation between its light and heavy hole valence bands, thereby giving rise to valence band convergence. Additionally, iodine doping in the Te sublattice of SnTe decreases the excess p-type carrier concentration. Due to significant decrease in hole concentration and reduction of the energy separation between light and heavy hole valence bands, significant enhancement in Seebeck coefficient was achieved at the temperature range of 600-900 K for Sn1-xAgxTe1-xIx samples. A maximum thermoelectric figure of merit, zT, of ~1.05 was achieved at 860 K in high quality crystalline ingot of p-type Sn0.95Ag0.05Te0.95I0.05.

  6. H2O/D2O exchange in the presence of CO over SnO2 nanomaterials: operando DRIFTS and resistance study for gas sensor applications

    NASA Astrophysics Data System (ADS)

    Pavelko, R. G.; Choi, J.-K.; Urakawa, A.; Yuasa, M.; Kida, T.; Shimanoe, K.; Yamazoe, N.

    2013-09-01

    Modulation excitation diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) together with resistance measurements has been carried out to study water isotopic exchange on undoped SnO2 materials as a function of CO concentration. We compare two materials synthesized via hydrothermal treatment and different only in their precursors: SnO2 Ac synthesized from tin(IV) hydroxide acetate and SnO2 Cl from tin(IV) chloride pentahydrate. DRIFTS and resistance measurements were performed simultaneously in an environmental chamber at 300 oC and in a flow of humid air. The annealed materials were found to have similar particle sizes (16+/-7 nm), crystallite sizes (12+/-2 nm) and pore size distribution (9+/-1 nm). However, sensor tests showed notably higher responses to CO in the presence of water vapor for SnO2 Ac. Electronic effect of CO chemisorption quantitatively correlates with consumption of bridging hydroxyls on the latter surface upon increasing concentration of CO from 0 to 500 ppm in humid air. No such correlation was found for SnO2 Cl. Water desorption kinetics was found to be slower for the latter by ca. 30 % with respect to SnO2 Ac. Low activity of surface OH groups and consequently low sensor signals of SnO2 Cl were proposed to originate from traces of Cl ions found in the material after the synthesis despite negative Cl test before the hydrothermal treatment.

  7. ISOTOPE CONVERSION DEVICE

    DOEpatents

    Wigner, E.P.; Young, G.J.; Ohlinger, L.A.

    1957-12-01

    This patent relates to nuclear reactors of tbe type utilizing a liquid fuel and designed to convert a non-thermally fissionable isotope to a thermally fissionable isotope by neutron absorption. A tank containing a reactive composition of a thermally fissionable isotope dispersed in a liquid moderator is disposed within an outer tank containing a slurry of a non-thermally fissionable isotope convertible to a thermally fissionable isotope by neutron absorption. A control rod is used to control the chain reaction in the reactive composition and means are provided for circulating and cooling the reactive composition and slurry in separate circuits.

  8. Isotopically controlled semiconductors

    SciTech Connect

    Haller, Eugene E.

    2001-12-21

    Semiconductor bulk crystals and multilayer structures with controlled isotopic composition have attracted much scientific and technical interest in the past few years. Isotopic composition affects a large number of physical properties, including phonon energies and lifetimes, bandgaps, the thermal conductivity and expansion coefficient and spin-related effects. Isotope superlattices are ideal media for self-diffusion studies. In combination with neutron transmutation doping, isotope control offers a novel approach to metal-insulator transition studies. Spintronics, quantum computing and nanoparticle science are emerging fields using isotope control.

  9. Spectrophotometric time series of SN 2011fe from the Nearby Supernova Factory

    NASA Astrophysics Data System (ADS)

    Pereira, R.; Thomas, R. C.; Aldering, G.; Antilogus, P.; Baltay, C.; Benitez-Herrera, S.; Bongard, S.; Buton, C.; Canto, A.; Cellier-Holzem, F.; Chen, J.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Fink, M.; Fouchez, D.; Gangler, E.; Guy, J.; Hillebrandt, W.; Hsiao, E. Y.; Kerschhaggl, M.; Kowalski, M.; Kromer, M.; Nordin, J.; Nugent, P.; Paech, K.; Pain, R.; Pécontal, E.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Saunders, C.; Smadja, G.; Tao, C.; Taubenberger, S.; Tilquin, A.; Wu, C.

    2013-06-01

    We present 32 epochs of optical (3300-9700 Å) spectrophotometric observations of the nearby quintessential "normal" type Ia supernova (SN Ia) SN 2011fe in the galaxy M101, extending from -15 to +97 d with respect to B-band maximum, obtained by the Nearby Supernova Factory collaboration. SN 2011fe is the closest (μ = 29.04) and brightest (Bmax = 9.94 mag) SN Ia observed since the advent of modern large scale programs for the intensive periodic followup of supernovae. Both synthetic light curve measurements and spectral feature analysis attest to the normality of SN 2011fe. There is very little evidence for reddening in its host galaxy. The homogeneous calibration, intensive time sampling, and high signal-to-noise ratio of the data set make it unique. Thus it is ideal for studying the physics of SN Ia explosions in detail, and for furthering the use of SNe Ia as standardizable candles for cosmology. Several such applications are shown, from the creation of a bolometric light curve and measurement of the 56Ni mass, to the simulation ofdetection thresholds for unburned carbon, direct comparisons with other SNe Ia, and existing spectral templates. A movie is available in electronic form at http://www.aanda.orgAll the reduced spectra are available as FITS files in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5">130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/554/A27

  10. Bursting SN 1996cr's bubble: hydrodynamic and X-ray modelling of its circumstellar medium

    NASA Astrophysics Data System (ADS)

    Dwarkadas, V. V.; Dewey, D.; Bauer, F.

    2010-09-01

    SN1996cr is one of the five closest supernovae (SNe) to explode in the past 30 yr. Due to its fortuitous location in the Circinus galaxy at ~3.7 Mpc, there is a wealth of recently acquired and serendipitous archival data available to piece together its evolution over the past decade, including a recent 485-ks Chandra high-energy transmission grating spectrum. In order to interpret these data, we have explored hydrodynamic simulations, followed by computations of simulated spectra and light curves under non-equilibrium ionization conditions, and directly compared them to the observations. Our simulated spectra manage to fit both the X-ray continuum and lines at four epochs satisfactorily, while our computed light curves are in good agreement with additional flux-monitoring data sets. These calculations allow us to infer the nature and structure of the circumstellar medium (CSM), the evolution of the SN shock wave, and the abundances of the ejecta and surrounding medium. The data imply that SN 1996cr exploded in a low-density medium before interacting with a dense shell of material about 0.03 pc away from the progenitor star. We speculate that the shell could be due to the interaction of a blue supergiant or Wolf-Rayet wind with a previously existing red supergiant (RSG) wind. The shock wave has now exited the shell and is expanding in the medium exterior to it, possibly the undisturbed continuation of the dense RSG wind. The narrow lines that earned SN 1996cr its IIn designation possibly arise from dense, shocked clumps in the CSM. Although the possibility for a luminous blue variable progenitor for this Type IIn SN cannot be completely excluded, it is inconsistent with much of the data. These calculations allow us to probe the stellar mass-loss in the very last phases (<104 yr) of a massive star's life (>106 yr), and provide another means to deducing the progenitor of the SN.

  11. Dissolution and Interfacial Reactions of (Cu,Ni)6Sn5 Intermetallic Compound in Molten Sn-Cu-Ni Solders

    NASA Astrophysics Data System (ADS)

    Wang, Chao-hong; Lai, Wei-han; Chen, Sinn-wen

    2014-01-01

    (Cu,Ni)6Sn5 is an important intermetallic compound (IMC) in lead-free Sn-Ag-Cu solder joints on Ni substrate. The formation, growth, and microstructural evolution of (Cu,Ni)6Sn5 are closely correlated with the concentrations of Cu and Ni in the solder. This study reports the interfacial behaviors of (Cu,Ni)6Sn5 IMC (Sn-31 at.%Cu-24 at.%Ni) with various Sn-Cu, Sn-Ni, and Sn-Cu-Ni solders at 250°C. The (Cu,Ni)6Sn5 substrate remained intact for Sn-0.7 wt.%Cu solder. When the Cu concentration was decreased to 0.3 wt.%, (Cu,Ni)6Sn5 significantly dissolved into the molten solder. Moreover, (Cu,Ni)6Sn5 dissolution and (Ni,Cu)3Sn4 formation occurred simultaneously for the Sn-0.1 wt.%Ni solder. In Sn-0.5 wt.%Cu-0.2 wt.%Ni solder, many tiny (Cu,Ni)6Sn5 particulates were formed and dispersed in the solder matrix, while in Sn-0.3 wt.%Cu-0.2 wt.%Ni a lot of (Ni,Cu)3Sn4 grains were produced. Based on the local equilibrium hypothesis, these results are further discussed based on the liquid-(Cu, Ni)6Sn5-(Ni,Cu)3Sn4 tie-triangle, and the liquid apex is suggested to be very close to Sn-0.4 wt.%Cu-0.2 wt.%Ni.

  12. SN 2010jl: Optical to hard X-ray observations reveal an explosion embedded in a ten solar mass cocoon

    SciTech Connect

    Ofek, Eran O.; Gal-Yam, Avishay; Arcavi, Iair; Zoglauer, Andreas; Boggs, Steven E.; Barriére, Nicolas M.; Reynolds, Stephen P.; Fryer, Chris L.; Even, Wesley; Harrison, Fiona A.; Kulkarni, Shrinivas R.; Bellm, Eric; Grefenstette, Brian; Cenko, S. Bradley; Bloom, Joshua S.; Filippenko, Alexei V.; Christensen, Finn; Craig, William W.; Hailey, Charles J.; Laher, Russ; and others

    2014-01-20

    Some supernovae (SNe) may be powered by the interaction of the SN ejecta with a large amount of circumstellar matter (CSM). However, quantitative estimates of the CSM mass around such SNe are missing when the CSM material is optically thick. Specifically, current estimators are sensitive to uncertainties regarding the CSM density profile and the ejecta velocity. Here we outline a method to measure the mass of the optically thick CSM around such SNe. We present new visible-light and X-ray observations of SN 2010jl (PTF 10aaxf), including the first detection of an SN in the hard X-ray band using NuSTAR. The total radiated luminosity of SN 2010jl is extreme—at least 9 × 10{sup 50} erg. By modeling the visible-light data, we robustly show that the mass of the circumstellar material within ∼10{sup 16} cm of the progenitor of SN 2010jl was in excess of 10 M {sub ☉}. This mass was likely ejected tens of years prior to the SN explosion. Our modeling suggests that the shock velocity during shock breakout was ∼6000 km s{sup –1}, decelerating to ∼2600 km s{sup –1} about 2 yr after maximum light. Furthermore, our late-time NuSTAR and XMM spectra of the SN presumably provide the first direct measurement of SN shock velocity 2 yr after the SN maximum light—measured to be in the range of 2000-4500 km s{sup –1} if the ions and electrons are in equilibrium, and ≳ 2000 km s{sup –1} if they are not in equilibrium. This measurement is in agreement with the shock velocity predicted by our modeling of the visible-light data. Our observations also show that the average radial density distribution of the CSM roughly follows an r {sup –2} law. A possible explanation for the ≳ 10 M {sub ☉} of CSM and the wind-like profile is that they are the result of multiple pulsational pair instability events prior to the SN explosion, separated from each other by years.

  13. Bottom-up processing and low temperature transport properties of polycrystalline SnSe

    SciTech Connect

    Ge, Zhen-Hua; Wei, Kaya; Lewis, Hutton; Martin, Joshua; Nolas, George S.

    2015-05-15

    A hydrothermal approach was employed to efficiently synthesize SnSe nanorods. The nanorods were consolidated into polycrystalline SnSe by spark plasma sintering for low temperature electrical and thermal properties characterization. The low temperature transport properties indicate semiconducting behavior with a typical dielectric temperature dependence of the thermal conductivity. The transport properties are discussed in light of the recent interest in this material for thermoelectric applications. The nanorod growth mechanism is also discussed in detail. - Graphical abstract: SnSe nanorods were synthesized by a simple hydrothermal method through a bottom-up approach. Micron sized flower-like crystals changed to nanorods with increasing hydrothermal temperature. Low temperature transport properties of polycrystalline SnSe, after SPS densification, were reported for the first time. This bottom-up synthetic approach can be used to produce phase-pure dense polycrystalline materials for thermoelectrics applications. - Highlights: • SnSe nanorods were synthesized by a simple and efficient hydrothermal approach. • The role of temperature, time and NaOH content was investigated. • SPS densification allowed for low temperature transport properties measurements. • Transport measurements indicate semiconducting behavior.

  14. Evolving into a remnant: optical observations of SN 1978K at three decades

    NASA Astrophysics Data System (ADS)

    Kuncarayakti, H.; Maeda, K.; Anderson, J. P.; Hamuy, M.; Nomoto, K.; Galbany, L.; Doi, M.

    2016-05-01

    We present new optical observations of the supernova SN 1978K, obtained in 2007 and 2014 with the Very Large Telescope. We discover that the supernova has not faded significantly, even more than three decades after its explosion. The spectrum exhibits numerous narrow (FWHM ≲600 km s-1) emission lines, indicating that the supernova blastwave is persistently interacting with dense circumstellar material (CSM). Evolution of emission lines indicates that the supernova ejecta is slowly progressing through the reverse shock, and has not expanded past the outer edge of the circumstellar envelope. We demonstrate that the CSM is not likely to be spherically distributed, with mass of ≲1 M⊙. The progenitor mass loss rate is estimated as ≳0.01 M⊙ yr-1. The slowly fading late-time light curve and spectra show striking similarity with SN 1987A, indicating that a rate at which the CSM is being swept-up by the blastwave is gradually decaying and SN 1978K is undergoing similar evolution to become a remnant. Due to its proximity (4 Mpc), SN 1978K serves as the next best example of late-time supernova evolution after SN 1987A.

  15. Hydrothermal synthesis and characteristic photoluminescence of Er-doped SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Tuan, Pham Van; Hieu, Le Trung; Nga, La Quynh; Dung, Nguyen Duc; Ha, Ngo Ngoc; Khiem, Tran Ngoc

    2016-11-01

    We report the characteristic photoluminescence (PL) spectra of erbium ion (Er3+)-doped tin dioxide (SnO2)nanoparticles. The materials were prepared via hydrothermal method at 180 °C with in 20 h by using various Er3+ ion concentrations ranging from 0.0 to 1.0 at%. After the synthesis, the materials were characterized through X-ray diffraction and high-resolution transmission electron microscopy. Crystallite SnO2 and its average particle diameter of approximately 5 nm did not change with Er3+ ion dopant concentration. Photoluminescence spectra showed the characteristic light emission from the Er3+ ions. The PL excitation spectra referred to an efficient energy transfer to Er3+ ions in the presence of SnO2nanoparticles. The most intense Er-related emission of SnO2:Er3+ nanoparticles in near infrared region was found in samples containing an Er3+ ion concentration of 0.25 at%. Although the absorption bandgaps of the materials were identified at approximately 3.8 eV, we found that efficient excitation comes with low excitation energy band edge. Excitation is possibly involved in shallow defects in SnO2 nanoparticles.

  16. Optical band-edge absorption of oxide compound SnO 2

    NASA Astrophysics Data System (ADS)

    Roman, L. S.; Valaski, R.; Canestraro, C. D.; Magalhães, E. C. S.; Persson, C.; Ahuja, R.; da Silva, E. F.; Pepe, I.; da Silva, A. Ferreira

    2006-05-01

    Tin oxide (SnO 2) is an important oxide for efficient dielectrics, catalysis, sensor devices, electrodes and transparent conducting coating oxide technologies. SnO 2 thin film is widely used in glass applications due to its low infra-red heat emissivity. In this work, the SnO 2 electronic band-edge structure and optical properties are studied employing a first-principle and fully relativistic full-potential linearized augmented plane wave (FPLAPW) method within the local density approximation (LDA). The optical band-edge absorption α( ω) of intrinsic SnO 2 is investigated experimentally by transmission spectroscopy measurements and their roughness in the light of the atomic force microscopy (AFM) measurements. The sample films were prepared by spray pyrolysis deposition method onto glass substrate considering different thickness layers. We found for SnO 2 qualitatively good agreement of the calculated optical band-gap energy as well as the optical absorption with the experimental results.

  17. Synthesis and photocatalytic properties of different SnO2 microspheres on graphene oxide sheets

    NASA Astrophysics Data System (ADS)

    Wei, Jia; Xue, Shaolin; Xie, Pei; Zou, Rujia

    2016-07-01

    Different SnO2 microspheres like dandelions, silkworm cocoons and urchins have been synthesized on graphene oxide sheets (GOs) by hydrothermal method at 190 °C for 24 h. The morphologies, structures, chemical compositions and optical properties of the as-grown SnO2 microspheres on GOs (SMGs) were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), X-ray energy dispersive spectrometer (EDS), Raman spectra and UV-vis diffuse reflectance spectra (DRS) techniques. The results of XRD revealed that the as-grown SnO2 microspheres have tetragonal rutile structure. The results of Raman spectra, EDS, XRD, XPS and SEM showed that the SnO2 microspheres were grown on GOs and the average diameter of dandelion-like microsphere was about 1.5 μm. The formation mechanism of SnO2 microspheres grown on GOs was discussed. The photocatalytic activity of the SMGs composites was evaluated by photocatalytic degradation of Rhodamine B (Rh B) aqueous solution under visible light irradiation. The photocatalytic results showed that the dandelion-like SMGs exhibited a much better photocatalytic activity than those of smooth and rough SMGs.

  18. MG Isotopic Measurement of FIB-Isolated Presolar Silicate Grains

    NASA Technical Reports Server (NTRS)

    Messenger, Scott R.; Nguyen, A.; Ito, M.; Rahman, Z.

    2010-01-01

    The majority of presolar oxide and silicate grains are ascribed to origins in low-mass red giant and asymptotic giant branch (AGB) stars based on their O isotopic ratios. However, a minor population of these grains (< 10%) has O isotopic ratios incompatible with these sources. Two principle alternative sources are higher-than-solar metallicity (Z) stars or, more likely, supernovae (SN) [1-3]. These rare (Group 4) grains [3] are characterized by enrichments in O-18, and typically also enrichments in O-17. An even rarer subset of grains with extremely large enrichments in O-17 and smaller depletions in O-18 were suggested to come from binary star systems [2]. To establish the origins of these isotopically unusual grains, it is necessary to examine isotopic systems in addition to O. Presolar silicates offer several elements diagnostic of their stellar sources and nuclear processes, including O, Si, Mg, Fe and Ca. However, the database for minor element isotopic compositions in silicates is seriously lacking. To date only two silicate grains have been analyzed for Mg [4] or Fe [5]. One major complicating factor is their small size (average 230 nm), which greatly limits the number of measurements that can be performed on any one grain and makes it more difficult to obtain statistically relevant data. This problem is compounded because the grains are identified among isotopically solar silicates, which contribute a diluting signal in isotopic measurements [1]. Thus, relatively small isotopic anomalies are missed due to this dilution effect. By applying focused ion beam (FIB) milling, we obtain undiluted Mg isotopic ratios of isolated rare presolar silicate grains to investigate their sources.

  19. The aerosol assisted chemical vapour deposition of SnSe and Cu₂SnSe₃ thin films from molecular precursors.

    PubMed

    Kevin, Punarja; Malik, Sajid N; Malik, Mohammad A; O'Brien, Paul

    2014-11-28

    Tin selenide (SnSe) and copper tin selenide (Cu2SnSe3) thin films have been deposited onto glass substrates by AACVD using [Sn(Ph2PSe2)2] or a mixture of [Sn(Ph2PSe2)2] and [Cu(acac)2] respectively. PMID:25284472

  20. Transparent Conducting Properties of SrSnO3 and ZnSnO3

    DOE PAGES

    Ong, Khuong P.; Fan, Xiaofeng; Subedi, Alaska; Sullivan, Michael B.; Singh, David J.

    2015-04-29

    We report optical properties of doped n-type SrSnO3 and ZnSnO3 in relation to potential application as transparent conductors. We find that the orthorhombic distortion of the perovskite structure in SrSnO3 leads to absorption in the visible as the doping level is increased. This arises from interband transitions. We find that strain tuning could modify this absorption, but does not eliminate it. On the other hand, we find that ZnSnO3 although also having a non-cubic structure, can retain excellent transparency when doped, making it a good candidate transparent conductor.

  1. High-velocity emission in young supernova remnants: SN 1006 and SN 1572

    SciTech Connect

    Kirshner, R.; Winkler, P.F.; Chevalier, R.A.

    1987-04-01

    The paper reports the discovery of broad H-alpha emission from the SN 1006 remnant with a FWHM velocity of 2600 + or - 100 km/s. This emission is similar to that seen in the remnant of SN 1572 which has a FWHM for H-alpha of 1800 km/s. The nonradiative model was used to interpret the line widths and the derived shock velocity was compared with proper motion measurements to derive distances of 1.4-2.1 kpc to SN 1006 and 2.0-2.8 kpc to SN 1572. 24 references.

  2. Effect of Sn addition on the microstructure and superelasticity in Ti-Nb-Mo-Sn alloys.

    PubMed

    Zhang, D C; Yang, S; Wei, M; Mao, Y F; Tan, C G; Lin, J G

    2012-09-01

    Ti-7.5Nb-4Mo-xSn (x=0-4at%) alloys were developed as the biomedical materials. The effect of the Sn content on the microstructure and superelasticity of the alloys was investigated. It is found that Sn is a strong stabilizer of the β phase, which is effective in suppressing the formation of α″ and ω phases in the alloys. Moreover, the Sn addition has a significant impact on the mechanical properties of the alloys. With the increase of Sn addition, the yield stress of the alloys increase, but their elastic modulus, the fracture strength and the ductility decrease, and the deformation mode of the alloys changes from (322) twining to α″ transformation and then to slip. The Ti-7.5Nb-4Mo-1Sn and Ti-7.5Nb-4Mo-3Sn alloys exhibit a good superelasticity with a high σ(SIM) due to the relatively high athermal ω phases containing or the solution hardening at room temperature. Under the maximum strain of 5%, Ti-7.5Nb-4Mo-3Sn (at%) alloy exhibits higher super elastic stability than that of Ti-7.5Nb-4Mo-1Sn alloy.

  3. Stable Chlorine Isotope Study: Application to Early Solar System Materials

    NASA Technical Reports Server (NTRS)

    Mala,ira. M/; Nyquist, L. E.; Reese, Y.; Shih, C-Y; Fujitani, T.; Okano, O.

    2010-01-01

    A significantly large mass fractionation between two stable chlorine isotopes is expected during planetary processes In addition, in view of the isotopic heterogeneity of other light elements, the chlorine isotopes can potentially be used as a tracer for the origins and evolutionary processes of early solar system materials. Due to analytical difficulties, however, current chlorine isotope studies on planetary materials are quite controversial among IRMS (gas source mass spectrometry) and/or TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1-3]. Although a cross-calibration of IRMS and TIMS indicates that both techniques are sufficiently consistent with each other [4], some authors have claimed that the Cl-37/Cl-35 ratio of geological samples obtained by TIMS technique are, in general, misleadingly too high and variable compared to those of IRMS [3]. For example, almost no differences of Cl isotope composition were observed among mantle materials and carbonaceous meteorites by [3]. On the other hand, according to more recent IRMS work [2], significant Cl isotope variations are confirmed for mantle materials. Therefore, additional careful investigation of Cl isotope analyses are now required to confirm real chlorine isotope variations for planetary materials including carbonaceous chondrites [5]. A significantly large mass fractionation between two stable chlorine isotopes is expected during planetary processes In addition, in view of the isotopic heterogeneity of other light elements, the chlorine isotopes can potentially be used as a tracer for the origins and evolutionary processes of early solar system materials. Due to analytical difficulties, however, current chlorine isotope studies on planetary materials are quite controversial among IRMS (gas source mass spectrometry) and/or TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1-3]. Although a cross-calibration of IRMS and TIMS indicates that both techniques are sufficiently consistent with each

  4. Anomalous creep in Sn-rich solder joints

    SciTech Connect

    Song, Ho Geon; Morris Jr., John W.; Hua, Fay

    2002-03-15

    This paper discusses the creep behavior of example Sn-rich solders that have become candidates for use in Pb-free solder joints. The specific solders discussed are Sn-3.5Ag, Sn-3Ag-0.5Cu, Sn-0.7Cu and Sn-10In-3.1Ag, used in thin joints between Cu and Ni-Au metallized pads.

  5. Highly sensitive and fast phototransistor based on large size CVD-grown SnS2 nanosheets

    NASA Astrophysics Data System (ADS)

    Huang, Yun; Deng, Hui-Xiong; Xu, Kai; Wang, Zhen-Xing; Wang, Qi-Sheng; Wang, Feng-Mei; Wang, Feng; Zhan, Xue-Ying; Li, Shu-Shen; Luo, Jun-Wei; He, Jun

    2015-08-01

    A facile and fruitful CVD method is reported for the first time, to synthesize high-quality hexagonal SnS2 nanosheets on carbon cloth via in situ sulfurization of SnO2. Moreover, highly sensitive phototransistors based on SnS2 with an on/off ratio surpassing 106 under ambient conditions and a rising time as short as 22 ms under vacuum are fabricated, which are superior than most phototransistors based on LMDs. Electrical transport measurements at varied temperatures together with theoretical calculations verify that sulfur vacancies generated by the growth process would induce a defect level near the bottom of the conduction band, which significantly affects the performance of the SnS2 device. These findings may open up a new pathway for the synthesis of LMDs, shed light on the effects of defects on devices and expand the building blocks for high performance optoelectronic devices.A facile and fruitful CVD method is reported for the first time, to synthesize high-quality hexagonal SnS2 nanosheets on carbon cloth via in situ sulfurization of SnO2. Moreover, highly sensitive phototransistors based on SnS2 with an on/off ratio surpassing 106 under ambient conditions and a rising time as short as 22 ms under vacuum are fabricated, which are superior than most phototransistors based on LMDs. Electrical transport measurements at varied temperatures together with theoretical calculations verify that sulfur vacancies generated by the growth process would induce a defect level near the bottom of the conduction band, which significantly affects the performance of the SnS2 device. These findings may open up a new pathway for the synthesis of LMDs, shed light on the effects of defects on devices and expand the building blocks for high performance optoelectronic devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04174k

  6. The Three-dimensional Circumstellar Environment of SN 1987A

    NASA Astrophysics Data System (ADS)

    Sugerman, Ben E. K.; Crotts, Arlin P. S.; Kunkel, William E.; Heathcote, Stephen R.; Lawrence, Stephen S.

    2005-07-01

    Surrounding SN 1987A is a three-ring nebula attributed to interacting stellar winds, yet no model has successfully reproduced this system. Fortunately, the progenitor's mass-loss history can be reconstructed using light echoes, in which scattered light from the supernova traces the three-dimensional morphology of its circumstellar dust. In this paper, we construct and analyze the most complete map to date of the progenitor's circumstellar environment, using ground- and space-based imaging from the past 16 years. PSF-matched difference-imaging analyses of data from 1988 through 1997 reveal material between 1 and 28 lt-yr from the SN. Previously known structures, such as an inner hourglass, Napoleon's Hat, and a contact discontinuity, are probed in greater spatial detail than before. Previously unknown features are also discovered, such as a southern counterpart to Napoleon's Hat. Careful analyses of these echoes allows the reconstruction of the probable circumstellar environment, revealing a richly structured bipolar nebula. An outer, double-lobed ``Peanut,'' which is believed to be the contact discontinuity between red supergiant and main-sequence winds, is a prolate shell extending 28 lt-yr along the poles and 11 lt-yr near the equator. Napoleon's Hat, previously believed to be an independent structure, is the waist of this Peanut, which is pinched to a radius of 6 lt-yr. Interior to this is a cylindrical hourglass, 1 lt-yr in radius and 4 lt-yr long, which connects to the Peanut by a thick equatorial disk. The nebulae are inclined 41° south and 8° east of the line of sight, slightly elliptical in cross section, and marginally offset west of the SN. From the hourglass to the large, bipolar lobes, echo fluxes suggest that the gas density drops from 1-3 to >~0.03 cm-3, while the maximum dust-grain size increases from ~0.2 to 2 μm, and the silicate:carbonaceous dust ratio decreases. The nebulae have a total mass of ~1.7 Msolar. The geometry of the three rings is

  7. Nitrogen abundances and isotopic compositions in lunar samples

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Clayton, R. N.

    1975-01-01

    Isotopic analyses were carried out on soil separates as well as on bulk samples. Analyses of nitrogen fractions obtained by step-wise heating of the separates were also conducted. It was also attempted to obtain a value for the isotopic composition of indigenous lunar nitrogen from analyses of igneous rock samples. Several breccias were also analyzed for their nitrogen isotope ratios. The significance of the obtained results is discussed. Several lines of evidence point to the conclusion that the isotope ratio of the nitrogen being implanted into the lunar regolith has increased by some 15% over a period of at least 450 million years and possibly as long as 3,700 million years or more. This may be the result of changes in the nitrogen isotope ratio of the solar wind with time, or it may be due to outgassing and subsequent reimplantation of an isotopically light indigenous lunar nitrogen from the lunar interior in the early history of the moon.

  8. SN 1054: A pulsar-powered supernova?

    NASA Astrophysics Data System (ADS)

    Li, Shao-Ze; Yu, Yun-Wei; Huang, Yan

    2015-11-01

    The famous ancient supernova SN 1054 could have been too bright to be explained in the “standard” radioactive-powered supernova scenario. As an alternative attempt, we demonstrate that the spin-down of the newly born Crab pulsar could provide a sufficient energy supply to make SN 1054 visible at daytime for 23 days and at night for 653 days, where a one-zone semi-analytical model is employed. Our results indicate that SN 1054 could be a “normal” cousin of magnetar-powered superluminous supernovae. Therefore, SN 1054-like supernovae could be a probe to uncover the properties of newly born neutron stars, which provide initial conditions for studies on neutron star evolutions.

  9. Asiago spectroscopic classification of SN 2016gdt

    NASA Astrophysics Data System (ADS)

    Ochner, P.; Benetti, S.; Cappellaro, E.; Elias-Rosa, N.; Pastorello, A.; Tomasella, L.; Turatto, M.; Terreran, G.

    2016-09-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classification of SN2016gdt in IC1407. The target was supplied by the Italian Supernovae Search Project (ISSP).

  10. A nontoxic and low-cost hydrothermal route for synthesis of hierarchical Cu2ZnSnS4 particles

    PubMed Central

    2014-01-01

    We explore a facile and nontoxic hydrothermal route for synthesis of a Cu2ZnSnS4 nanocrystalline material by using l-cysteine as the sulfur source and ethylenediaminetetraacetic acid (EDTA) as the complexing agent. The effects of the amount of EDTA, the mole ratio of the three metal ions, and the hydrothermal temperature and time on the phase composition of the obtained product have been systematically investigated. The addition of EDTA and an excessive dose of ZnCl2 in the hydrothermal reaction system favor the generation of kesterite Cu2ZnSnS4. Pure kesterite Cu2ZnSnS4 has been synthesized at 180°C for 12 h from the reaction system containing 2 mmol of EDTA at 2:2:1 of Cu/Zn/Sn. It is confirmed by Raman spectroscopy that those binary and ternary phases are absent in the kesterite Cu2ZnSnS4 product. The kesterite Cu2ZnSnS4 material synthesized by the hydrothermal process consists of flower-like particles with 250 to 400 nm in size. It is revealed that the flower-like particles are assembled from single-crystal Cu2ZnSnS4 nanoflakes with ca. 20 nm in size. The band gap of the Cu2ZnSnS4 nanocrystalline material is estimated to be 1.55 eV. The films fabricated from the hierarchical Cu2ZnSnS4 particles exhibit fast photocurrent responses under intermittent visible-light irradiation, implying that they show potentials for use in solar cells and photocatalysis. PMID:24855463

  11. Molybdenum isotope systematics in subduction zones

    NASA Astrophysics Data System (ADS)

    König, Stephan; Wille, Martin; Voegelin, Andrea; Schoenberg, Ronny

    2016-08-01

    This study presents Mo isotope data for arc lavas from different subduction zones that range between δ 98 / 95 Mo = - 0.72 and + 0.07 ‰. Heaviest isotope values are observed for the most slab fluid dominated samples. Isotopically lighter signatures are related to increasing relevance of terrigenous sediment subduction and sediment melt components. Our observation complements previous conclusions that an isotopically heavy Mo fluid flux likely mirrors selective incorporation of isotopically light Mo in secondary minerals within the subducting slab. Analogue to this interpretation, low δ 98 / 95 Mo flux that coincides with terrigenous sediment subduction and sediment melting cannot be simply related to a recycled input signature. Instead, breakdown of the controlling secondary minerals during sediment melting may release the light component and lead to decreasing δ 98 / 95 Mo influx into subarc mantle sources. The natural range between slab dehydration and hydrous sediment melting may thus cause a large spread of δ 98 / 95 Mo in global subduction zone magmas.

  12. Particle-hole states in Sn 120

    NASA Technical Reports Server (NTRS)

    Leonard, R. F.

    1972-01-01

    The 45 MeV deuteron beam from the Berkeley 88-inch cyclotron was used to study the particle-hole states in Sn-120. The present work resolved a number of individual levels and compared their strength and excitation energy with that observed in the Sn-120(d, He-3) reaction, which was also remeasured. A schematic diagram of the scattering system is given along with a description.

  13. The Fast Evolution of SN 2010bh Associated with XRF 100316D

    NASA Technical Reports Server (NTRS)

    Olivares E., F.; Greiner, J.; Schady, P.; Rau, A.; Klose, S.; Kruhler, T.; Afonso, P. M. J.; Updike, A. C.; Nardini, M.; Filgas, R.; Nicuesa Guelbenzu, A.; Clemens, C.; Elliott, J.; Kann, D. A.; Rossi, A.; Sudilovsky, V.

    2012-01-01

    The first observational evidence of a connection between supernovae (SNe) and gamma-ray bursts (GRBs) was found about a decade ago. Since then, only half a dozen spectroscopically confirmed associations have been discovered and XRF 1003160 associated with the type-Ic SN 20lObh is among the latest. Aims. We constrain the progenitor radius, the host-galaxy extinction, and the physical parameters of the explosion of XRF l00316D/SN 20lObh at z 0.059. We study the SN brightness and colours in the context of GRB-SNe. Methods. We began observations with the Gamma-Ray burst Optical and Near-infrared Detector (GROND) 12 hours after the GRB trigger and continued until 80 days after the burst. GROND provided excellent photometric data in six filter bands covering a wavelength range from approximately 350 to 1800 nm, significantly expanding the pre-existing data set for this event. Combining GROND and Swift data, the early broad-band spectral energy distribution (SED) is modelled with a blackbody and afterglow component attenuated by dust and gas absorption. The temperature and radius evolution of the thermal component are analysed and combined with earlier measurements available from the literature. Templates of SN 1998bw are fitted to the SN itself to directly compare the lightcurve properties. Finally, a two-component parametrized model is fitted to the quasi-bolometric light curve. which delivers physical parameters of the explosion. Results. The best-fit models to the broad-band SEDs imply moderate reddening along the line of sight through the host galaxy (A(sub v.host = 1.2 +/- 0.1 mag). Furthermore, the parameters of the blackbody component reveal a cooling envelope at an apparent initial radius of 7 x 10(exp 11) cm, which is compatible with a dense wind surrounding a Wolf-Rayet star. A multicolor comparison shows that SN 2010bh is 60 - 70% as bright as SN 1998bw. Reaching maximum brightness at 8 - 9 days after the burst in the blue bands, SN 20lObh proves to be the

  14. Semiconducting ZnSn{sub x}Ge{sub 1−x}N{sub 2} alloys prepared by reactive radio-frequency sputtering

    SciTech Connect

    Shing, Amanda M.; Coronel, Naomi C.; Lewis, Nathan S.; Atwater, Harry A.

    2015-07-01

    We report on the fabrication and structural and optoelectronic characterization of II-IV-nitride ZnSn{sub x}Ge{sub 1−x}N{sub 2} thin-films. Three-target reactive radio-frequency sputtering was used to synthesize non-degenerately doped semiconducting alloys having <10% atomic composition (x = 0.025) of tin. These low-Sn alloys followed the structural and optoelectronic trends of the alloy series. Samples exhibited semiconducting properties, including optical band gaps and increasing in resistivities with temperature. Resistivity vs. temperature measurements indicated that low-Sn alloys were non-degenerately doped, whereas alloys with higher Sn content were degenerately doped. These films show potential for ZnSn{sub x}Ge{sub 1−x}N{sub 2} as tunable semiconductor absorbers for possible use in photovoltaics, light-emitting diodes, or optical sensors.

  15. Wet chemical synthesis and self-assembly of SnS2 nanoparticles on TiO2 for quantum dot-sensitized solar cells.

    PubMed

    Tsukigase, Hiroki; Suzuki, Yoshikazu; Berger, Marie-Hélène; Sagawa, Takashi; Yoshikawa, Susumu

    2011-04-01

    SnS2 nanoparticles were synthesized through a simple wet chemical process at room temperature. The SnS2 nanoparticles were approximately spherical in shape and had diameter about 3-4 nm. SnS2-sensitized TiO2 electrodes were fabricated by the immersion of chemically modified TiO2 to well-dispersed SnS2 solution for 72 h (i.e., self-assembly method.) SnS2-sensitized TiO2 electrodes were applied in quantum dot-sensitized solar cells (QDSSCs). Under AM1.5 irradiation with 100 mW/cm2 light intensity (at 1 sun), the short-circuit current density (J(sc)), the open-circuit voltage (V(oc)), the fill factor (FF), and the energy conversion efficiency (eta) were 0.47 mA/cm2, 0.29 V, 0.58 and 0.081%, respectively.

  16. High luminosity, slow ejecta and persistent carbon lines: SN 2009dc challenges thermonuclear explosion scenarios

    NASA Astrophysics Data System (ADS)

    Taubenberger, S.; Benetti, S.; Childress, M.; Pakmor, R.; Hachinger, S.; Mazzali, P. A.; Stanishev, V.; Elias-Rosa, N.; Agnoletto, I.; Bufano, F.; Ergon, M.; Harutyunyan, A.; Inserra, C.; Kankare, E.; Kromer, M.; Navasardyan, H.; Nicolas, J.; Pastorello, A.; Prosperi, E.; Salgado, F.; Sollerman, J.; Stritzinger, M.; Turatto, M.; Valenti, S.; Hillebrandt, W.

    2011-04-01

    Extended optical and near-IR observations reveal that SN 2009dc shares a number of similarities with normal Type Ia supernovae (SNe Ia), but is clearly overluminous, with a (pseudo-bolometric) peak luminosity of log (L) = 43.47 (erg s-1). Its light curves decline slowly over half a year after maximum light [Δm15(B)true= 0.71], and the early-time near-IR light curves show secondary maxima, although the minima between the first and the second peaks are not very pronounced. The bluer bands exhibit an enhanced fading after ˜200 d, which might be caused by dust formation or an unexpectedly early IR catastrophe. The spectra of SN 2009dc are dominated by intermediate-mass elements and unburned material at early times, and by iron-group elements at late phases. Strong C II lines are present until ˜2 weeks past maximum, which is unprecedented in thermonuclear SNe. The ejecta velocities are significantly lower than in normal and even subluminous SNe Ia. No signatures of interaction with a circumstellar medium (CSM) are found in the spectra. Assuming that the light curves are powered by radioactive decay, analytic modelling suggests that SN 2009dc produced ˜1.8 M⊙ of 56Ni assuming the smallest possible rise time of 22 d. Together with a derived total ejecta mass of ˜2.8 M⊙, this confirms that SN 2009dc is a member of the class of possible super-Chandrasekhar-mass SNe Ia similar to SNe 2003fg, 2006gz and 2007if. A study of the hosts of SN 2009dc and other superluminous SNe Ia reveals a tendency of these SNe to explode in low-mass galaxies. A low metallicity of the progenitor may therefore be an important prerequisite for producing superluminous SNe Ia. We discuss a number of possible explosion scenarios, ranging from super-Chandrasekhar-mass white-dwarf progenitors over dynamical white-dwarf mergers and Type I? SNe to a core-collapse origin of the explosion. None of the models seems capable of explaining all properties of SN 2009dc, so that the true nature of this SN

  17. Unveiling Type IIb Supernova Progenitors: SN 2011hs from a Supergiant Star

    NASA Astrophysics Data System (ADS)

    Bufano, F.

    2014-10-01

    Type IIb Supernovae are the final evolutionary stage of massive stars that were able to retain only a thin (lesssim 1 M_{odot}) H/He external envelope at the time of the explosion. The mechanism of mass-loss that made such final structure possible and the nature of such progenitor stars are still open issues. We present the results obtained from the study of a sample of Type IIb SNe, in particular, of SN 2011hs (Bufano et al., 2013, MNRAS submitted). SN 2011hs was a relatively faint (M_{B} = -15.6 mag) and red Type IIb SN, characterized by a narrow light curve shape. Its spectral evolution showed the metamorphosis typical of this class of SN, from spectra dominated by H I lines to spectra where He I features dominate, but with broad absorption line profiles indicating high expansion velocities. Modeling the light curve of SN 2011hs and its velocity evolution with hydrodynamical calculations, we estimated that the SN is consistent with the explosion of a 3-4 M_{odot} He-core star, from a main sequence mass of 12-15 M_{odot}, ejecting a ^{56}Ni mass equal to 0.04 M_{odot} and characterized by an explosion energy of E≍ 8.5× 10^{50} erg s^{-1}. Based on the light curve evolution, we assumed that the explosion occurred 6 days before the discovery (2,455,872 ± 4 JD), resulting in an adiabatic cooling phase lasting 8 days, similarly to SN 1993J. Since the duration and the decreasing rate of the cooling branch depends mainly on the progenitor size, we could infer from it a progenitor radius of ≍ 500-600 R_{odot}, like a supergiant star. Our modeling rules out models with He core mass >5 M_{odot}, i.e. main sequence masses above 20 M_{odot}. Such a lower limit for the progenitor mass could indicate the possibility of a binary origin, although the radio light curve does not show strong deviations, typically signature of the presence of a companion star.

  18. Isotopic Evidence of Unaccounted for Fe and Cu Erythropoietic Pathways

    NASA Astrophysics Data System (ADS)

    Albarede, F.; Telouk, P.; Lamboux, A.; Jaouen, K.; Balter, V.

    2011-12-01

    Despite its potential importance for understanding perturbations in the Fe-Cu homeostatic pathways, the natural isotopic variability of these metals in the human body remains unexplored. We measured the Fe, Cu, and Zn isotope compositions of total blood, serum, and red blood cells of ~50 young blood donors by multiple-collector ICP-MS after separation and purification by anion exchange chromatography. Zn is on average 0.2 permil heavier in erythrocytes (δ 66Zn=0.44±0.33 permil) with respect to serum but shows much less overall isotopic variability than Fe and Cu, which indicates that isotope fractionation depends more on redox conditions than on ligand coordination. On average, Fe in erythrocytes (δ 56Fe=-2.59±0.47 permil) is isotopically light by 1-2 permil with respect to serum, whereas Cu in erythrocytes (δ 65Cu=0.56±0.50 permil) is 0.8 percent heavier. Fe and Cu isotope compositions clearly separate erythrocytes of men and women. Fe and Cu from B-type men erythrocytes are visibly more fractionated than all the other blood types. Isotope compositions provide an original method for evaluating metal mass balance and homeostasis. Natural isotope variability shows that the current models of Fe and Cu erythropoiesis, which assume that erythropoiesis is restricted to bone marrow, violate mass balance requirements. It unveils unsuspected major pathways for Fe, with erythropoietic production of isotopically heavy ferritin and hemosiderin, and for Cu, with isotopically light Cu being largely channeled into blood and lymphatic circulation rather than into superoxide dismutase-laden erythrocytes. Iron isotopes provide an intrinsic measuring rod of the erythropoietic yield, while Cu isotopes seem to gauge the relative activity of erythropoiesis and lymphatics.

  19. Isotopic Fractionation of Selenium Oxyanions in Wetlands

    NASA Astrophysics Data System (ADS)

    Clark, S. K.; Johnson, T. M.

    2004-05-01

    species-specific information than those from previous studies, but they similarly suggest that Se(VI) uptake is dominated by plant or algae assimilation: a process that involves little or no isotopic fractionation. On the other hand, Se(IV) is likely reduced by microbes or abiotic reductants in the sediments. The slight shift toward isotopically lighter Se(VI) is enigmatic, but could be due to oxidation of isotopically light dimethylselenide to Se(VI) in the water column.

  20. Copper isotopic composition of the silicate Earth

    NASA Astrophysics Data System (ADS)

    Liu, Sheng-Ao; Huang, Jian; Liu, Jingao; Wörner, Gerhard; Yang, Wei; Tang, Yan-Jie; Chen, Yi; Tang, Limei; Zheng, Jianping; Li, Shuguang

    2015-10-01

    Copper isotopes have been successfully applied to many fields in geochemistry, and in particular, as a strongly chalcophile element, the isotope systematics of Cu can be potentially applied as a proxy for crust-mantle and core-mantle differentiation processes. However, to date, the Cu isotopic composition of distinct silicate reservoirs in the Earth, as well as the behaviour of Cu isotopes during igneous processes and slab dehydration are not well constrained. To address these issues, here we report high-precision (±0.05‰; 2SD) Cu isotope data for 132 terrestrial samples including 28 cratonic peridotites, 19 orogenic peridotites, 70 basalts (MORBs, OIBs, arc basalts and continental basalts) and 15 subduction-related andesites/dacites sourced worldwide. The peridotites are classified into metasomatized and non-metasomatized groups, based upon their rare earth element (REE) patterns and the presence or lack of minerals diagnostic of metasomatism (e.g., phlogopite). The metasomatized peridotites span a wide range of δ65Cu values from -0.64 to +1.82‰, in sharp contrast to the non-metasomatized peridotites that exhibit a narrow range of δ65Cu from -0.15 to +0.18‰ with an average of + 0.03 ± 0.24 ‰ (2SD). Comparison between these two groups of peridotites demonstrates that metasomatism significantly fractionates Cu isotopes with sulfide breakdown and precipitation potentially shifting Cu isotopes towards light and heavy values, respectively. MORBs and OIBs have homogeneous Cu isotopic compositions (+ 0.09 ± 0.13 ‰; 2SD), which are indistinguishable from those of the non-metasomatized peridotites within uncertainty. This suggests that Cu isotope fractionation during mantle partial melting is limited, even if sulfides are a residual phase. Compared with MORBs and OIBs, arc and continental basalts are more heterogeneous in Cu isotopic composition. In particular, basalts that were collected from a traverse across the Kamchatka arc over a distance of 200 to 400

  1. Calcium isotopic composition of mantle peridotites

    NASA Astrophysics Data System (ADS)

    Huang, F.; Kang, J.; Zhang, Z.

    2015-12-01

    Ca isotopes are useful to decipher mantle evolution and the genetic relationship between the Earth and chondrites. It has been observed that Ca isotopes can be fractionated at high temperature [1-2]. However, Ca isotopic composition of the mantle peridotites and fractionation mechanism are still poorly constrained. Here, we report Ca isotope composition of 12 co-existing pyroxene pairs in 10 lherzolites, 1 harzburgite, and 1 wehrlite xenoliths collected from Hainan Island (South Eastern China). Ca isotope data were measured on a Triton-TIMS using the double spike method at the Guangzhou Institute of Geochemistry, CAS. The long-term external error is 0.12‰ (2SD) based on repeated analyses of NIST SRM 915a and geostandards. δ44Ca of clinopyroxenes except that from the wehrlite ranges from 0.85‰ to 1.14‰, while opx yields a wide range from 0.98‰ up to 2.16‰. Co-existing pyroxene pairs show large ∆44Caopx-cpx (defined as δ44Caopx-δ44Cacpx) ranging from 0 to 1.23‰, reflecting equilibrium fractionation controlled by variable Ca contents in the opx. Notably, clinopyroxene of wehrlite shows extremely high δ44Ca (3.22‰). δ44Ca of the bulk lherzolites and harzburgites range from 0.86‰ to 1.14‰. This can be explained by extracting melts with slightly light Ca isotopic compositions. Finally, the high δ44Ca of the wehrlite (3.22‰) may reflect metasomatism by melt which has preferentially lost light Ca isotopes due to chemical diffusion during upwelling through the melt channel. [1] Amini et al (2009) GGR 33; [2] Huang et al (2010) EPSL 292.

  2. Iron isotopic fractionation during continental weathering

    SciTech Connect

    Fantle, Matthew S.; DePaolo, Donald J.

    2003-10-01

    The biological activity on continents and the oxygen content of the atmosphere determine the chemical pathways through which Fe is processed at the Earth's surface. Experiments have shown that the relevant chemical pathways fractionate Fe isotopes. Measurements of soils, streams, and deep-sea clay indicate that the {sup 56}Fe/{sup 54}Fe ratio ({delta}{sup 56}Fe relative to igneous rocks) varies from +1{per_thousand} for weathering residues like soils and clays, to -3{per_thousand} for dissolved Fe in streams. These measurements confirm that weathering processes produce substantial fractionation of Fe isotopes in the modern oxidizing Earth surface environment. The results imply that biologically-mediated processes, which preferentially mobilize light Fe isotopes, are critical to Fe chemistry in weathering environments, and that the {delta}{sup 56}Fe of marine dissolved Fe should be variable and negative. Diagenetic reduction of Fe in marine sediments may also be a significant component of the global Fe isotope cycle. Iron isotopes provide a tracer for the influence of biological activity and oxygen in weathering processes through Earth history. Iron isotopic fractionation during weathering may have been smaller or absent in an oxygen-poor environment such as that of the early Precambrian Earth.

  3. Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition.

    PubMed

    Jaramillo, Rafael; Steinmann, Vera; Yang, Chuanxi; Hartman, Katy; Chakraborty, Rupak; Poindexter, Jeremy R; Castillo, Mariela Lizet; Gordon, Roy; Buonassisi, Tonio

    2015-05-22

    Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, for a long time the record power conversion efficiency of SnS solar cells remained below 2%. Recently we demonstrated new certified record efficiencies of 4.36% using SnS deposited by atomic layer deposition, and 3.88% using thermal evaporation. Here the fabrication procedure for these record solar cells is described, and the statistical distribution of the fabrication process is reported. The standard deviation of efficiency measured on a single substrate is typically over 0.5%. All steps including substrate selection and cleaning, Mo sputtering for the rear contact (cathode), SnS deposition, annealing, surface passivation, Zn(O,S) buffer layer selection and deposition, transparent conductor (anode) deposition, and metallization are described. On each substrate we fabricate 11 individual devices, each with active area 0.25 cm(2). Further, a system for high throughput measurements of current-voltage curves under simulated solar light, and external quantum efficiency measurement with variable light bias is described. With this system we are able to measure full data sets on all 11 devices in an automated manner and in minimal time. These results illustrate the value of studying large sample sets, rather than focusing narrowly on the highest performing devices. Large data sets help us to distinguish and remedy individual loss mechanisms affecting our devices.

  4. Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition.

    PubMed

    Jaramillo, Rafael; Steinmann, Vera; Yang, Chuanxi; Hartman, Katy; Chakraborty, Rupak; Poindexter, Jeremy R; Castillo, Mariela Lizet; Gordon, Roy; Buonassisi, Tonio

    2015-01-01

    Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, for a long time the record power conversion efficiency of SnS solar cells remained below 2%. Recently we demonstrated new certified record efficiencies of 4.36% using SnS deposited by atomic layer deposition, and 3.88% using thermal evaporation. Here the fabrication procedure for these record solar cells is described, and the statistical distribution of the fabrication process is reported. The standard deviation of efficiency measured on a single substrate is typically over 0.5%. All steps including substrate selection and cleaning, Mo sputtering for the rear contact (cathode), SnS deposition, annealing, surface passivation, Zn(O,S) buffer layer selection and deposition, transparent conductor (anode) deposition, and metallization are described. On each substrate we fabricate 11 individual devices, each with active area 0.25 cm(2). Further, a system for high throughput measurements of current-voltage curves under simulated solar light, and external quantum efficiency measurement with variable light bias is described. With this system we are able to measure full data sets on all 11 devices in an automated manner and in minimal time. These results illustrate the value of studying large sample sets, rather than focusing narrowly on the highest performing devices. Large data sets help us to distinguish and remedy individual loss mechanisms affecting our devices. PMID:26067454

  5. Optical observations of the broad-lined type Ic supernova SN 2012ap

    NASA Astrophysics Data System (ADS)

    Liu, Zheng; Zhao, Xu-Lin; Huang, Fang; Wang, Xiao-Feng; Zhang, Tian-Meng; Chen, Jun-Cheng; Zhang, Tong-Jie

    2015-02-01

    The optical observations of the type Ic supernova (SN Ic) SN 2012ap in NGC 1729 are presented. A comparison with other SNe Ic indicates that SN 2012ap is highly reddened (with E(B — V)host~0.8 mag) and may represent one of the most luminous SNe Ic ever observed, with an absolute V-band peak magnitude of ~ -19.3±0.5 mag after extinction correction. The near-maximum-light spectrum shows wide spectral features that are typical of broad-lined SNe Ic. One interesting feature in the spectrum is the appearance of some narrow absorption features that can be attributed to the diffuse interstellar bands, consistent with the large reddening inferred from the photometric method. Based on the light curves and the spectral data, we estimate that SN 2012ap produced a 56Ni mass of ~ 0.3 ± 0.1Msolar 1 in the explosion, with an ejecta mass of 2.4-0.7+0.7Msolar and a kinetic energy of EK = 1.1-0.4+0.4 × 1052 erg. The properties of its progenitor are also briefly discussed.

  6. Lighting: Green Light.

    ERIC Educational Resources Information Center

    Maniccia, Dorine

    2003-01-01

    Explains that by using sustainable (green) building practices, schools and universities can make their lighting systems more efficient, noting that embracing green design principles can help schools attract students. Discusses lighting-control technologies (occupancy sensing technology, daylighting technology, and scheduling based technologies),…

  7. Tycho Brahe's Supernova: Light from Centuries Past

    NASA Astrophysics Data System (ADS)

    Ruiz-Lapuente, Pilar

    2004-09-01

    The light curve of SN 1572 is described in the terms used nowadays to characterize Type Ia supernovae (SNe Ia). By assembling the records of the observations done in 1572-1574 and evaluating their uncertainties, it is possible to recover the light curve and the color evolution of this supernova. It is found that within the SN Ia family, the event should have been an SN Ia with a normal rate of decline, its stretch factor being s~0.9. The visual light curve near maximum, late-time decline, and color evolution sustain this conclusion. After correcting for extinction, the luminosity of this supernova as observed at maximum is found to be MV=-19.24-5log(D/3.0kpc)+/-0.42. From stretch fitting of the overall light curve, the maximum in V would imply a luminosity difference of +0.17+/-0.1 mag, with the maximum brightness of an s=1 SN Ia. The quantity MV is consistent with a distance of 2.8+/-0.4 kpc for the scale of H0=65 km s-1 Mpc-1.

  8. A study on 100 MeV O7+ irradiated SnO2/Ag/SnO2 multilayer as transparent electrode for flat panel display application

    NASA Astrophysics Data System (ADS)

    Sharma, Vikas; Singh, Satyavir; Asokan, K.; Sachdev, Kanupriya

    2016-07-01

    The multilayer thin films of SnO2/Ag/SnO2 were deposited using electron-beam and thermal evaporation for flat panel display application. The as-prepared SnO2/Ag/SnO2 specimen was irradiated with 100 MeV O7+ ions by varying the fluences 1 × 1012 and 5 × 1012 ions/cm2. The pristine and irradiated films were investigated using XRD, SEM, AFM and Raman to find out modification in the structure and surface morphology of the films. UV-Vis and Hall measurement techniques were used to investigate the optical and electrical properties respectively. It was observed that the roughness of the film after irradiation (for the fluence of 1 × 1012 ions/cm2) ​ decreased to 0.68 nm from 1.6 nm and showed an increase in roughness to 1.35 nm on increasing the fluence to 5 × 1012 ions/cm2. This oxide/metal/oxide structure fulfills the basic requirements of a TCE, like high-transmittance >75% for pristine and >80% for the fluence of 1 × 1012 ions/cm2 over a broad spectrum of visible light for practical applications. The multilayer structure shows change in the electrical resistivity from 1.6 × 10-3 Ω cm to 6.3 × 10-3 Ω cm after irradiation.

  9. The behaviour of copper isotopes during igneous processes

    NASA Astrophysics Data System (ADS)

    Savage, P. S.; Moynier, F.; Harvey, J.; Burton, K. W.

    2015-12-01

    Application of Cu isotopes to high temperature systems has recently gained momentum and has the potential for probing sulphide fractionation during planetary differentiation [1]. This requires robust estimates for planetary reservoirs, and a fundamental understanding of how igneous processes affect Cu isotopes; this study aims to tackle the latter. Cogenetic suites affected by both fractionation crystallisation and cumulate formation were analysed to study such effects on Cu isotopes. In S-undersatured systems, Cu behaves incompatibly during melt evolution and the Cu isotope composition of such melt is invariant over the differentiation sequence. In contrast, S-saturated systems show resolvable Cu isotope variations relative to primitive melt. Such variations are minor but imply a slightly heavy Cu isotope composition for continental crust compared to BSE, consistent with granite data [2]. Although olivine accumulation does not affect Cu isotopes, spinel-hosted Cu is isotopically light relative to the bulk. Analysis of variably melt-depleted cratonic peridotites shows that partial melting can affect Cu isotope composition in restite, with the depleted samples isotopically light compared to BSE. This could be due to residual spinel and/or incongruent melting of sulphides - individual sulphides picked from a single xenolith reveal a range of Cu isotope compositions, dependent on composition. Although partial melting may fractionate Cu isotopes, models suggest most mantle-derived melt will have δ65Cu ≈ BSE, as most source Cu will be transferred to the melt. Small degree melts such as ocean island basalts are predicted to be isotopically heavier than MORB, if derived from a primitive mantle source. OIBs have a range of Cu isotope compositions: some are heavier than MORB as predicted; however, some have much lighter compositions. Since Cu isotopes can be significantly fractionated in the surface environment [e.g. 3] OIB Cu isotopic variations may be linked to

  10. The isotopic composition of cosmic ray chlorine

    NASA Technical Reports Server (NTRS)

    Wiedenbeck, M. E.

    1985-01-01

    The isotopic composition of galactic cosmic ray chlorine (approx. = 225 MeV/amu) has been studied using the high energy cosmic ray experiment on the International Sun Earth Explorer 3 (ISEE-3) spacecraft. The abundances of 35C1 and 37C1 are found to be consistent with the secondary production expected from a propagation model developed to account for both light and subiron secondaries. An upper limit on the abundance of the radioactive isotope 36C1 (halflife approx. = 0.3 Myr) is used to set a lower limit on the confinement time of cosmic rays of approximately 1 Myr.

  11. Oxygen and carbon isotope disequilibria in Galapagos corals: isotopic thermometry and calcification physiology

    SciTech Connect

    McConnaughey, T.A.

    1986-01-01

    Biological carbonate skeletons are built largely from carbon dioxide, which reacts to form carbonate ion within thin extracellular solutions. The light isotopes of carbon and oxygen react faster than the heavy isotopes, depleting the resulting carbonate ions in /sup 13/C and /sup 18/O. Calcium carbonate precipitation occurs sufficiently fast that the skeleton remains out of isotopic equilibrium with surrounding fluids. This explanation for isotopic disequilibrium in biological carbonates was partially simulated in vitro, producing results similar to those seen in non-photosynthetic corals. Photosynthetic corals have higher /sup 13/C//sup 12/C ratios due to the preferential removal of /sup 12/C (as organic carbon) from the reservoir of dissolved inorganic carbon. The oxygen isotopic variations in corals can be used to reconstruct past sea surface temperatures to an accuracy of about 0.5/sup 0/C. The carbon isotopic content of photosynthetic corals provides an indication of cloudiness. Using isotopic data from Galapagos corals, it was possible to construct proxy histories of the El Nino phenomenon. The physiology of skeletogenesis appears to be surprisingly similar in calcium carbonate, calcium phosphate, and silica precipitating systems.

  12. OISTER optical and near-infrared observations of the super-Chandrasekhar supernova candidate SN 2012dn: Dust emission from the circumstellar shell

    NASA Astrophysics Data System (ADS)

    Yamanaka, Masayuki; Maeda, Keiichi; Tanaka, Masaomi; Tominaga, Nozomu; Kawabata, Koji S.; Takaki, Katsutoshi; Kawabata, Miho; Nakaoka, Tatsuya; Ueno, Issei; Akitaya, Hiroshi; Nagayama, Takahiro; Takahashi, Jun; Honda, Satoshi; Omodaka, Toshihiro; Miyanoshita, Ryo; Nagao, Takashi; Watanabe, Makoto; Isogai, Mizuki; Arai, Akira; Itoh, Ryosuke; Ui, Takahiro; Uemura, Makoto; Yoshida, Michitoshi; Hanayama, Hidekazu; Kuroda, Daisuke; Ukita, Nobuharu; Yanagisawa, Kenshi; Izumiura, Hideyuki; Saito, Yoshihiko; Masumoto, Kazunari; Ono, Rikako; Noguchi, Ryo; Matsumoto, Katsura; Nogami, Daisaku; Morokuma, Tomoki; Oasa, Yumiko; Sekiguchi, Kazuhiro

    2016-05-01

    We present extensively dense observations of the super-Chandrasekhar supernova (SC SN) candidate SN 2012dn from -11 to +140 d after the date of its B-band maximum in the optical and near-infrared (NIR) wavelengths conducted through the OISTER ToO (Optical and Infrared Synergetic Telescopes for Education and Research Target of Opportunity) program. The NIR light curves and color evolutions up to 35 days after the B-band maximum provided an excellent match with those of another SC SN 2009dc, providing further support to the nature of SN 2012dn as an SC SN. We found that SN 2012dn exhibited strong excesses in the NIR wavelengths from 30 d after the B-band maximum. The H- and Ks-band light curves exhibited much later maximum dates at 40 and 70 d after the B-band maximum, respectively, compared with those of normal SNe Ia. The H- and Ks-band light curves subtracted by those of SN 2009dc displayed plateaued evolutions, indicating an NIR echo from the surrounding dust. The distance to the inner boundary of the dust shell is limited to 4.8-6.4 × 10-2 pc. No emission lines were found in its early phase spectra, suggesting that the ejecta-circumstellar material interaction could not occur. On the other hand, we found no signature that strongly supports the scenario of dust formation. The mass-loss rate of the pre-explosion system is estimated to be 10-6-10-5 M⊙ yr-1, assuming that the wind velocity of the system is 10-100 km s-1, which suggests that the progenitor of SN 2012dn could be a recurrent nova system. We conclude that the progenitor of this SC SN could be explained by the single-degenerate scenario.

  13. OISTER optical and near-infrared observations of the super-Chandrasekhar supernova candidate SN 2012dn: Dust emission from the circumstellar shell

    NASA Astrophysics Data System (ADS)

    Yamanaka, Masayuki; Maeda, Keiichi; Tanaka, Masaomi; Tominaga, Nozomu; Kawabata, Koji S.; Takaki, Katsutoshi; Kawabata, Miho; Nakaoka, Tatsuya; Ueno, Issei; Akitaya, Hiroshi; Nagayama, Takahiro; Takahashi, Jun; Honda, Satoshi; Omodaka, Toshihiro; Miyanoshita, Ryo; Nagao, Takashi; Watanabe, Makoto; Isogai, Mizuki; Arai, Akira; Itoh, Ryosuke; Ui, Takahiro; Uemura, Makoto; Yoshida, Michitoshi; Hanayama, Hidekazu; Kuroda, Daisuke; Ukita, Nobuharu; Yanagisawa, Kenshi; Izumiura, Hideyuki; Saito, Yoshihiko; Masumoto, Kazunari; Ono, Rikako; Noguchi, Ryo; Matsumoto, Katsura; Nogami, Daisaku; Morokuma, Tomoki; Oasa, Yumiko; Sekiguchi, Kazuhiro

    2016-10-01

    We present extensively dense observations of the super-Chandrasekhar supernova (SC SN) candidate SN 2012dn from -11 to +140 d after the date of its B-band maximum in the optical and near-infrared (NIR) wavelengths conducted through the OISTER ToO (Optical and Infrared Synergetic Telescopes for Education and Research Target of Opportunity) program. The NIR light curves and color evolutions up to 35 days after the B-band maximum provided an excellent match with those of another SC SN 2009dc, providing further support to the nature of SN 2012dn as an SC SN. We found that SN 2012dn exhibited strong excesses in the NIR wavelengths from 30 d after the B-band maximum. The H- and Ks-band light curves exhibited much later maximum dates at 40 and 70 d after the B-band maximum, respectively, compared with those of normal SNe Ia. The H- and Ks-band light curves subtracted by those of SN 2009dc displayed plateaued evolutions, indicating an NIR echo from the surrounding dust. The distance to the inner boundary of the dust shell is limited to 4.8-6.4 × 10-2 pc. No emission lines were found in its early phase spectra, suggesting that the ejecta-circumstellar material interaction could not occur. On the other hand, we found no signature that strongly supports the scenario of dust formation. The mass-loss rate of the pre-explosion system is estimated to be 10-6-10-5 M⊙ yr-1, assuming that the wind velocity of the system is 10-100 km s-1, which suggests that the progenitor of SN 2012dn could be a recurrent nova system. We conclude that the progenitor of this SC SN could be explained by the single-degenerate scenario.

  14. Mössbauer studies of heteroleptic Sn(II) derivatives

    NASA Astrophysics Data System (ADS)

    de Lima, G. M.; Pierssens, L. J.-M.; Mahieu, B.

    1999-11-01

    The heteroleptic Sn(II) derivatives, [Sn(η5-C5Me5)Cl] (1), [{Sn(η5-C5Me4SiMe2But)} {Sn(η5-C5Me4SiMe2But)(OSO2CF3)}] (2), [{Sn(η5-C5Me5)}{Sn(η5-C5Me5)(OSO2CF3)}] (3) and [(Sn{N(SiMe3)2}{OSO2CF3})2] (4), were prepared and characterized by 119Sn Mössbauer spectroscopy, as well as by other techniques such as multinuclear NMR (solution- and solid-state) spectroscopy and X-ray crystallography. The 119Sn Mössbauer spectroscopic data were in good agreement with the other solid state results rendering additional support for the elucidation of bonding and structural features of these compounds.

  15. Copper and tin isotopic analysis of ancient bronzes for archaeological investigation: development and validation of a suitable analytical methodology.

    PubMed

    Balliana, Eleonora; Aramendía, Maite; Resano, Martin; Barbante, Carlo; Vanhaecke, Frank

    2013-03-01

    Although in many cases Pb isotopic analysis can be relied on for provenance determination of ancient bronzes, sometimes the use of "non-traditional" isotopic systems, such as those of Cu and Sn, is required. The work reported on in this paper aimed at revising the methodology for Cu and Sn isotope ratio measurements in archaeological bronzes via optimization of the analytical procedures in terms of sample pre-treatment, measurement protocol, precision, and analytical uncertainty. For Cu isotopic analysis, both Zn and Ni were investigated for their merit as internal standard (IS) relied on for mass bias correction. The use of Ni as IS seems to be the most robust approach as Ni is less prone to contamination, has a lower abundance in bronzes and an ionization potential similar to that of Cu, and provides slightly better reproducibility values when applied to NIST SRM 976 Cu isotopic reference material. The possibility of carrying out direct isotopic analysis without prior Cu isolation (with AG-MP-1 anion exchange resin) was investigated by analysis of CRM IARM 91D bronze reference material, synthetic solutions, and archaeological bronzes. Both procedures (Cu isolation/no Cu isolation) provide similar δ (65)Cu results with similar uncertainty budgets in all cases (±0.02-0.04 per mil in delta units, k = 2, n = 4). Direct isotopic analysis of Cu therefore seems feasible, without evidence of spectral interference or matrix-induced effect on the extent of mass bias. For Sn, a separation protocol relying on TRU-Spec anion exchange resin was optimized, providing a recovery close to 100 % without on-column fractionation. Cu was recovered quantitatively together with the bronze matrix with this isolation protocol. Isotopic analysis of this Cu fraction provides δ (65)Cu results similar to those obtained upon isolation using AG-MP-1 resin. This means that Cu and Sn isotopic analysis of bronze alloys can therefore be carried out after a single chromatographic

  16. Method for making a photodetector with enhanced light absorption

    DOEpatents

    Kane, James

    1987-05-05

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  17. Synthesis and Behavior of Cetyltrimethyl Ammonium Bromide Stabilized Zn1+xSnO3+x (0 ≤ x ≤1) Nano-Crystallites

    PubMed Central

    Placke, Astrid; Kumar, Ashok; Priya, Shashank

    2016-01-01

    We report synthesis of cetyltrimethyl ammonium bromide (CTAB) stabilized Zn1+xSnO3+x (0 ≤ x ≤1) nano-crystallites by facile cost-effective wet chemistry route. The X-ray diffraction patterns of as-synthesized powders at the Zn/Sn ratio of 1 exhibited formation of ZnSn(OH)6. Increasing the Zn/Sn ratio further resulted in the precipitation of an additional phase corresponding to Zn(OH)2. The decomposition of these powders at 650°C for 3h led to the formation of the orthorhombic phase of ZnSnO3 and tetragonal SnO2-type phase of Zn2SnO4 at the Zn/Sn ratio of 1 and 2, respectively, with the formation of their mixed phases at intermediate compositions, i.e., at Zn/Sn ratio of 1.25, 1.50 and 1.75, respectively. The lattice parameters of orthorhombic and tetragonal phases were a ~ 3.6203 Å, b ~ 4.2646 Å and c ~ 12.8291Å (for ZnSnO3) and a = b ~ 5.0136 Å and c ~ 3.3055Å (for Zn2SnO4). The transmission electron micrographs revealed the formation of nano-crystallites with aspect ratio ~ 2; the length and thickness being 24, 13 nm (for ZnSnO3) and 47, 22 nm (for Zn2SnO4), respectively. The estimated direct bandgap values for the ZnSnO3 and Zn2SnO4 were found to be 4.21 eV and 4.12 eV, respectively. The ac conductivity values at room temperature (at 10 kHz) for the ZnSnO3 and Zn2SnO4 samples were 8.02 × 10−8 Ω-1 cm-1 and 6.77 × 10−8 Ω-1 cm-1, respectively. The relative permittivity was found to increase with increase in temperature, the room temperature values being 14.24 and 25.22 for the samples ZnSnO3 and Zn2SnO4, respectively. Both the samples, i.e., ZnSnO3 and Zn2SnO4, exhibited low values of loss tangent up to 300 K, the room temperature values being 0.89 and 0.72, respectively. A dye-sensitized solar cell has been fabricated using the optimized sample of zinc stannate photo-anode, i.e., Zn2SnO4. The cyclic voltammetry revealed oxidation and reduction around 0.40 V (current density ~ 11.1 mA/cm2) and 0.57 V (current density– 11.7 mA/cm2) for Zn2SnO4

  18. Synthesis and Behavior of Cetyltrimethyl Ammonium Bromide Stabilized Zn1+xSnO3+x (0 ≤ x ≤1) Nano-Crystallites.

    PubMed

    Placke, Astrid; Kumar, Ashok; Priya, Shashank

    2016-01-01

    We report synthesis of cetyltrimethyl ammonium bromide (CTAB) stabilized Zn1+xSnO3+x (0 ≤ x ≤1) nano-crystallites by facile cost-effective wet chemistry route. The X-ray diffraction patterns of as-synthesized powders at the Zn/Sn ratio of 1 exhibited formation of ZnSn(OH)6. Increasing the Zn/Sn ratio further resulted in the precipitation of an additional phase corresponding to Zn(OH)2. The decomposition of these powders at 650°C for 3h led to the formation of the orthorhombic phase of ZnSnO3 and tetragonal SnO2-type phase of Zn2SnO4 at the Zn/Sn ratio of 1 and 2, respectively, with the formation of their mixed phases at intermediate compositions, i.e., at Zn/Sn ratio of 1.25, 1.50 and 1.75, respectively. The lattice parameters of orthorhombic and tetragonal phases were a ~ 3.6203 Å, b ~ 4.2646 Å and c ~ 12.8291Å (for ZnSnO3) and a = b ~ 5.0136 Å and c ~ 3.3055Å (for Zn2SnO4). The transmission electron micrographs revealed the formation of nano-crystallites with aspect ratio ~ 2; the length and thickness being 24, 13 nm (for ZnSnO3) and 47, 22 nm (for Zn2SnO4), respectively. The estimated direct bandgap values for the ZnSnO3 and Zn2SnO4 were found to be 4.21 eV and 4.12 eV, respectively. The ac conductivity values at room temperature (at 10 kHz) for the ZnSnO3 and Zn2SnO4 samples were 8.02 × 10-8 Ω-1 cm-1 and 6.77 × 10-8 Ω-1 cm-1, respectively. The relative permittivity was found to increase with increase in temperature, the room temperature values being 14.24 and 25.22 for the samples ZnSnO3 and Zn2SnO4, respectively. Both the samples, i.e., ZnSnO3 and Zn2SnO4, exhibited low values of loss tangent up to 300 K, the room temperature values being 0.89 and 0.72, respectively. A dye-sensitized solar cell has been fabricated using the optimized sample of zinc stannate photo-anode, i.e., Zn2SnO4. The cyclic voltammetry revealed oxidation and reduction around 0.40 V (current density ~ 11.1 mA/cm2) and 0.57 V (current density- 11.7 mA/cm2) for Zn2SnO4 photo

  19. Solution-based synthesis of wurtzite Cu2ZnSnS4 nanoleaves introduced by α-Cu2S nanocrystals as a catalyst

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Zhai, Lanlan; He, Na; Zou, Chao; Geng, Xiaozhen; Cheng, Lujun; Dong, Youqing; Huang, Shaoming

    2013-08-01

    Cu2ZnSnS4 is a promising solar absorbing material in solar cells due to its high absorption coefficient and abundance on earth. We have demonstrated that wu