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  • ASTROPHYSICS  (472)
  • Inorganic Chemistry  (356)
  • 2015-2019
  • 1975-1979  (633)
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  • 1930-1934  (69)
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  • 1
    Publication Date: 2011-08-17
    Description: The infrared spectrum of the Kleinmann-Low nebula in M42 has been measured from 80 to 350 kaysers (approximately 29 to 125 microns) with a Michelson interferometer aboard the NASA Kuiper Airborne Observatory. The frequency spectrum peaks at about 185 kaysers. A simple model of the emission implies that the temperature is in the range 70-95 K and that the optical depth is at least 0.2 at the peak frequency. A possible absorption is seen at about 176 kaysers. Thermal emission by dust at a temperature of 71 K, with the absorption cross section proportional to frequency, provides a good fit to the data. Other thermal-emission models can also fit the spectrum. The data are compared with previous broad-band measurements. Upper limits are placed on expected line emission from the surrounding H II region at the position of the nebula.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
    Format: text
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  • 2
    Publication Date: 2016-06-07
    Description: Monte Carlo-based computer calculations, as well as analytical approaches utilizing probabilistic arguments, were applied to gain insight into the principal regolith impact processes and their resulting kinetics. Craters 10 to 1500 m in diameter are largely responsible for the overall growth of the regolith. As a consequence the regolith has to be envisioned as a complex sequence of discrete ejecta blankets. Such blankets constitute first-order discontinuities in the evolving debris layer. The micrometeoroid complex then operates intensely on these fresh ejecta blankets and accomplishes only in an uppermost layer of approximately 1-mm thickness. The absolute flux of micrometeoroids based on lunar rock analyses averaged over the past few 10 to the 6th power years is approximately an order of magnitude lower than presentday satellite fluxes; however, there is indication that the flux increased in the past 10 to the 4th power years to become compatible with the satellite data. Furthermore, there is detailed evidence that the micrometeoroid complex existed throughout geologic time.
    Keywords: ASTROPHYSICS
    Type: The Soviet-Am. Conf. on Cosmochem. of the Moon and Planets, Pt. 2; p 605-635
    Format: application/pdf
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  • 3
    Publication Date: 2019-06-27
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 225
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  • 4
    Publication Date: 2019-06-27
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 5
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of Thallium(I) Hexaiodomercurate(II), Tl4HgI6In the structure of the tetragonal Tl4HgI6 (a = 944.6 pm, c = 926.0 pm, Z = 2, space group P 4/mnc) isolated, in c-direction compressed HgI6 octahedra are situated. The mercury atoms are disordered; they occupy statistically 4 positions in the equatorial plane of the octahedra in such a manner that strongly deformed HgI4 tetrahedra are produced. The thallium atoms are eightfold coordinated like a bicapped trigonal prism. The relationship between the Tl4HgI6 structure and the cubical K2PtCl6 type will be discussed.
    Notes: In der Struktur des tetragonalen Tl4HgI6 (a = 944,6 pm, c = 926,0 pm, Z = 2, Raumgruppe P 4/mnc) liegen isolierte, in Richtung der c-Achse gestauchte HgI6-Oktaeder vor. Die Quecksilberatome sind fehlgeordnet; sie besetzen statistisch 4 Positionen in der Äquatorebene der Oktaeder derart, daß stark verzerrte HgI4-Tetraeder entstehen. Die Thallium-Atome sind achtfach in Form eines bicapped trigonalen Prismas koordiniert. Die Beziehungen der Tl4HgI6-Struktur zum kubischen K2PtCl6-Typ werden diskutiert.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organocobalt-Clusterverbindungen. 26. Die Darstellung von Mercaptosubstituenten enthaltenden Methylidyntricobaltnonacarbonyl-KomplexenDie Umsetzung von Bromo- und Chloromethylidyntricobaltnonacarbonyl, XCCo3(CO)9 (X = Br, Cl) mit Zinndimethylbis(alkylmercaptiden), (CH3)2Sn(SR)2 in Toluol unter Rückfluß in 20-30 min stellt eine gute Methode zur Herstellung von schwefelsubstituierten Methylidyntricobaltnonacarbonylkomplexen des Typs RSCCo3(CO)9 (R = Alkyl, Aryl, Acetyl, Benzoyl) dar. Ebenfalls effektiv, aber weniger praktisch waren Trimethylzinnalkylmercaptide und Quecksilber-bis(ethylmercaptid).
    Notes: The reaction of bromo- and chloromethylidynetricobalt nonacarbonyl, XCCo3(CO)9 (X = Br, Cl) with dimethyltin bis (alkyl mercaptides), (CH3)2Sn(SR)2, in toluene solution at reflux for 20-30 min provides a useful procedure for the preparation of sulfur-substituted methylidynetricobalt nonacarbonyl complexes of type RSCCo3(CO)9 (R = alkyl, aryl, acetyl, benzoyl). Also effective, but less practical, in such applications were trimethyltin alkylmercaptides and mercury bis (ethyl mercaptide).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 29Si-NMR Spectroscopy of Silicate Solutions. II. On the Dependence of the Structure of Silicate Anions in Water Solutions from the Na : Si RatioThe 29Si-FT-NMR spectra of 13 sodiumsilicate solutions with different Na:Si ratios are investigated with regard to the structure of the silicate anions in the solutions. The 5 typical building units (Monosilicate, end-, middle-, branching and crosslinking groups) show characteristic and non overlapping ranges of the 29Si chemical shift with many signals splittings caused by different neighbouring group effects. The relative intensities of the signals give informations on the concentrations and the equilibrium of condensation of the silicate anions in dependence of the Na:Si ratio. It is shown, that many types of anions with different degree of condensation coexist in an equilibrium, which is shiftet to the polymer silicate anions with high content of branching and crosslinking groups on the decrease of the Na:Si ratio.
    Notes: Die 29Si-FT-NMR-Spektren von 13 Natriumsilicatlösungen mit unterschiedlichem Na:Si-Verhältnis werden in Hinblick auf die Struktur der in den Lösungen auftretenden Silicatanionen untersucht. Für die 5 möglichen Baugruppen (Monosilicat, Endgruppen. Mittelgruppen, Verzweigungs- und Vernetzungsgruppen) lassen sich definierte Bereiche der 29Si-chemischen Verschiebung angeben, in denen durch Einfluß der weiteren strukturellen Umgebung i. a. zahlreiche Signalaufspaltungen beobachtet werden. Aus den relativen Intensitäten der Signale können Aussagen über die Konzentrationsverteilung und damit über das Kondensationsgleichgewicht der Silicatanionen in Abhängigkeit vom Na:Si-Verhältnis abgeleitet werden. Es zeigt sich, daß zahlreiche Anionentypen mit unterschiedlichem Kondensationsgrad nebeneinander in einem Gleichgewicht vorliegen, das sich mit fallendem Na:Si-Verhältnis stark auf die Seite höhermolekularer Silicatanionen mit hohem Gehalt an Verzweigungs- und Vernetzungsgruppen verschiebt.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 439 (1978), S. 265-274 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Hydrates of Na2PHO3, Phase Relations and Crystallographic InvestigationsDehydration of Na2PHO3,5 H2O to the respective anhydrous salt was investigated by thermogravimetry and differential thermal analysis. In the course of dehydration an intermediate lower hydrate is formed, Na2PHO3,0.5 H2O. Single crystals of this phase were grown from solution. Na2PHO3,0.5 H2O is rhombohedral, space group R32, R3m or R3m, with a = 18.918(5) Å and α = 33.00(2)°. - The crystal structure of Na2PHO3,5 H2O was redetermined. The pentahydrate is orthorhomic, space group Pnm21, with a = 7.190(1), b = 6.447(1), c = 9.230(2) Å. The structure consists of layers of Na-coordinating polyhedra which share edges and vertices. The layers are connected to a threedimensional structure by hydrogen bonds of the water molecules.
    Notes: Die Dehydratisierung von NaaPHO3 · 5 H2O zum wasserfreien Salz wurde mit Thermogravimetrie und Differentialthermoanalyse untersucht. Die Entwässerung verläuft über die Stufe eines intermediären niederen Hydrates, Na2PHO3 · 0,5 H2O. Einkristalle des Hemihydrates konnten aus Lösung gezüchtet werden; es kristallisiert rhomboedrisch, Raumgruppe R32, R3m oder R3m, mit a = 18,918(5) ß und α = 33,00(2)°. - Die Kristallstruktur von Na2PHO3 · 5 H2O wurde neu bestimmt. Das Pentahydrat kristallisiert orthorhombisch, Raumgruppe Pnm21 mit a = 7,109(1), b = 6,447(1), c = 9,230(2) Å. Die Struktur ist aus Schichten von kanten- und eckenverknüpften Na-Koordinationspolyedern aufgebaut. Die Schichten werden durch Wasserstoffbrückenbindungen der Wassermoleküle zu einem dreidimensionalen Strukturverband verknüpft.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 2006-08-09
    Description: Gamma ray astronomy is now beginning to provide a new look at the galactic structure and the distribution of cosmic rays, both electrons and nucleons, within the galaxy. The observations are consistent with a galactic spiral-arm model in which the cosmic rays are linearly coupled to the interstellar gas on the scale of the spiral arms. The agreement between the predictions of the model and the observations for regions of the plane where both 21-cm and 2.6-mm CO surveys exist emphasizes the need to extend these observations to include the entire plane. Future gamma-ray observations with more sensitivity and better angular resolutions, combined with these radio surveys, should shed new light on the distribution of cosmic rays, the nature of the galaxy, and the location and intensity of the spiral arms.
    Keywords: ASTROPHYSICS
    Type: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 301-314
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  • 10
    Publication Date: 2011-08-16
    Description: The Second Small Astronomy Satellite (SAS-2) high-energy (in excess of 35 MeV) gamma-ray telescope has detected pulsed gamma-ray emission at the radio period from PSR 0833-45, the Vela pulsar, as well as an unpulsed flux from the Vela region. The pulsed emission consists of two peaks following the single radio peak by about 13 ms and 48 ms. The luminosity of the pulsed emission above 100 MeV from Vela is about 0.1 that of the pulsar NP 0532 in the Crab nebula, whereas the pulsed emission from Vela at optical wavelengths is less than 0.0002 that from the Crab. The relatively high intensity of the pulsed gamma-ray emission, and the double peak structure, compared with the single pulse in the radio emission, suggest that the high-energy gamma-ray pulsar emission may be produced under different conditions from those at lower energies.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 200; Sept. 1
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