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  • ASTROPHYSICS  (10)
  • General Chemistry  (2)
  • Earth Resources and Remote Sensing
  • Fisheries
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  • Polymer and Materials Science
  • 1985-1989  (13)
  • 1
    Electronic Resource
    Electronic Resource
    Comparison of the voltammetric behavior of adsorbed or dissolved unsaturated alcohols at vacuum-annealed and electrochemically cycled Pt(111) and Pt(polycrystalline) electrodes (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 213-221 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: These studies compare the voltammetric behavior of solutions and adsorbed layers of the following unsaturated alcohols: benzyl alcohol (BZA), 4-pyridylcarbinol (4PC), allyl alcohol (AA), propargyl alcohol (PGA), cis-2-butene-1,4-diol (CBED), and 2-butyne-1,4-diol (BYD). They were undertaken for well-characterized Pt(111) electrode surfaces which were either annealed in an ultrahigh vacuum (UHV) or electrochemically cycled, as well as for annealed (UHV) Pt(poly). Electrochemical oxidation of BZA, AA, PGA, CBED, and BYD in aqueous fluoride electrolyte proceeds in two stages: first the alcohol moiety is oxidized to CO2 (0.4 V), followed by oxidation of the resulting adsorbed hydrocarbon (alkene, alkyne, or phenyl, 1.0 V); 4PC is relatively inert. The alcohol moiety in 4PC, which is located opposite the pyridine ring from the surface, does not undergo oxidation at an appreciable rate. in fact, 4PC effectively passivates the surface and poisons the electrochemical activity. Electrochemical cycling of the annealed Pt(111) single-crystal surface greatly increases the oxidation rates of the aliphatic alcohols and, to a lesser extent, increases the oxidation rate of BZA. The oxidation rate enhancement is somewhat smaller if the electrode is electrochemically cycled in the presence of the alcohol. The majority of the difference effected by cycling can be observed after only one cycle. Voltammetry on polycrystalline Pt surfaces resembles that on cycled Pt(111) surfaces for PGA and AA, but resembles that on cycled Pt(111) surfaces for PGA and AA, but resembles that on annealed Pt(111) more closely for the diols CBED and BYD.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140010305
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Zweikernkomplexe mit vorhersagbaren magnetischen Eigenschaften (1985)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 97 (1985), S. 837-853 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ein Komplex, der zwei oder mehr paramagnetische übergangsmetall-Ionen enthält, kann völlig andere magnetische Eigenschaften haben als Einkernkomplexe dieser Ionen. Die Eigenschaften von Zweikernkomplexen hängen von Art und Stärke der Metall-Metall-Wechselwirkungen über die verbrückenden Liganden ab. Weisen beide Ionen je ein ungepaartes Elektron auf (z. B. Cu2+-Ionen), dann ist der energetische Grundzustand des Moleküls entweder ein Spin-Singulett oder ein Spin-Triplett. Im ersten Fall spricht man von antiferromagnetischer, im zweiten von ferromagnetischer Wechselwirkung. Art und Stärke der Wechselwirkung können durch die Wahl der Metall-Ionen sowie der verbrückenden und der terminalen Liganden und damit durch die Symmetrie und die Delokalisierung der metallzentrierten Orbitale, die von den ungepaarten Elektronen besetzt sind (magnetische Orbitale), gesteuert werden. Dies gelang zuerst bei einem rein ferromagnetischen Cu2+VO2+-Komplex. Die gleiche Strategie konnte zur Herstellung molekularer Ferromagnete genutzt werden, die eine der größten Herausforderungen auf dem Feld molekularer Werkstoffe ist. Man kann das Ausmaß der Wechselwirkung in einer vorgegebenen verbrückten Struktureinheit durch Variation der terminalen Liganden, die die Rolle von „Justierschrauben“ übernehmen, genau abstimmen. Durch die sorgfältige Wahl sowohl der verbrückenden als auch der terminalen Liganden kann eine sehr starke antiferromagnetische Wechselwirkung erreicht werden, sogar im Falle weit voneinander entfernter Metall-Ionen. Einige schwefelhaltige Brücken sind dafür besonders geeignet.
    Additional Material: 29 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19850971008
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  • 3
    Electronic Resource
    Electronic Resource
    Dinuclear Complexes with Predictable Magnetic Properties (1985)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 24 (1985), S. 834-850 
    Details
    ISSN: 0570-0833
    Keywords: Dinuclear complexes ; Complexes ; Magnetic properties ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When two paramagnetic transition metal ions are present in the same molecular entity, the magnetic properties can be totally different from the sum of the magnetic properties of each ion surrounded by its nearest neighbors. These new properties depend on the nature and the magnitude of the interaction between the metal ions through the bridging ligands. If both ions have an unpaired electron (e.g. Cu2+ ions), then the molecular state of lowest energy is either a spin singlet or a spin triplet. In the former case, the interaction is said to be antiferromagnetic, in the latter case ferromagnetic. The nature and the order of magnitude of the interaction can be engineered by judiciously choosing the interacting metal ions and the bridging and terminal ligands, and, thus, by the symmetry and the delocalization of the orbitals centered on the metal ions and occupied by the unpaired electrons (magnetic orbitals). The first success in this “molecular engineering” of bimetallic compounds was in the synthesis of a Cu2+VO2+ heterobimetallic complex in which the interaction is purely ferro-magnetic. The same strategy could be utilized for designing molecular ferromagnets, one of the major challenges in the area of molecular materials. Another striking result is the possibility of tuning the magnitude of the interaction through a given bridging network by modifying the nature of the terminal ligands, which, in some way, play the role of “adjusting screws”. By careful selection of the bridging and terminal ligands, a very large antiferro-magnetic interaction can be achieved, even if the metal ions are far away from each other. Some sulfur-containing bridges are especially suitable in this respect.
    Additional Material: 29 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.198508341
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  • 4
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    A multi-wavelength study of the long-period AM Her system E2003+225. I - The soft X-ray light curve and overall energy spectrum (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: X-ray, UV and optical data are presented of the longest period AM Her object, E2003+225, from October 12, 1983, together with a new linear polarization ephemeris. The optical and X-ray data were obtained simultaneously and the UV observations were carried out on the same day. A 6-hr observation with the Exosat 500 line/mm objective grating restricts soft X-ray blackbody temperatures to the range 18-29 eV. The blackbody luminosity exceeds the hard X-ray luminosity by at least a factor of 4.5, but is of the same order as the optical/UV component. Soft (0.1-0.25 keV) and hard X-ray (1-6 keV) light curves covering almost two orbital periods are presented and discussed.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 221; 823-838
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  • 5
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    Long-term temporal variability of Cygnus X-2 (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Observations of the low-mass binary X-ray source Cyg X-2 taken over a five-year period using instruments on OSO 8, HEAO 1, and Einstein are presented. Irregular changes in intensity of up to 60 percent on time scales ranging from minutes to days are seen. The source appears to have long-term low-luminosity states during which dips lasting about three days occur. When these long dips occur, they always appear at the same phase in the optically determined 9.8-day orbital period. There are three distinct types of short-term dips distinguished by differing correlations between spectral hardness and intensity.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 329; 276-289
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  • 6
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    X-ray spectroscopy of the ultrasoft transient 4U 1543 - 47 (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The X-ray transient 4U 1543 - 47 was observed in August 1983 by the Exosat observatory near the maximum of an outburst. The X-ray spectrum was measured using a gas scintillation proportional counter (GSPC) and a transmission grating spectrometer (TGS). A broad (FWHM about 2.7 keV) line at 5.9 keV is detected in the GSPC, which is interpreted as a redshifted and broadened iron K-alpha line. The line broadening and redshift may arise from either Compton scattering in a cool plasma with small optical depth and/or from Droppler and relativistic effects in the vicinity of compact object. The spectrum below 2 keV, obtained with the TGS, shows evidence for a broad emission feature at 0.74 keV, which may be an iron L-transition complex. However, such an emission feature could be an artifact caused by an anomalously low interstellar absorption by neutral oxygen. The contimuum emission is extremely soft and is well described by an unsaturated Comptonized spectrum from very cool plasma (kT = 0.84 keV) with large scattering depth.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 344; 320-324
    Format: text
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  • 7
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    Soft X-ray emission lines from low-mass X-ray binaries. I - Collision-dominated models (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The soft X-ray line emission from five low-mass X-ray binaries observed by the Einstein Observatory (HEAO 2) Objective Grating Spectrometer is examined. Observed spectra are fitted to model spectra consisting of emission from an optically thin plasma. Fits are performed using a variety of different assumptions for elemental abundances, heating and ionization mechanisms, and the distribution of gas temperature and ionization parameter. The results are discussed in the context of current models for the accretion flow in low-mass X-ray binaries.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 345; 498-504
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  • 8
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    Einstein observations of selected regions of the Cygnus Loop (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The imaging proportional counter on the Einstein X-ray Observatory is used to obtain high quality soft X-ray maps of two 40 x 40 arcmin regions of the Cygnus Loop. One region covers the western shock front; the other is centered on the southern diffuse extension. After careful correction for background and detector gain variations these two regions were subdivided for X-ray spectral analysis. In both cases the spectra of the brightest X-ray emitting areas are characterized by temperatures of about 2 million K, whereas the spectra of the fainter diffuse regions are indicative of higher temperatures (T greater than about 4 million K) and suggest the presence of a second, hard component. These results, together with the correlation of the X-ray spatial distribution with the optical and radio maps, are discussed in terms of current models of supernova remnant evolution. The evidence suggests that the Cygnus Loop is the result of a Type II supernova of a star of initial mass of less than about 20 solar masses.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 295; 456-462
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  • 9
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    X-ray emission lines from three Galactic bulge sources (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: X-ray spectroscopic observations obtained with the Einstein objective grating spectrometer (OGS) and monitor proportional counter (MPC) instruments of three Galactic bulge sources, the globular cluster burst source 1820-30, the burster Serpens X-1, and the GX 9+9 are presented. Joint spectral fits to the OGS and MPC data are consistent for all three sources with either a thermal bremsstrahlung model with temperature ranging from 6 to 10 keV or with a two-component blackbody model, where one component may be associated with the neutron star and one with the accretion disk. The spectra of Serpens X-1 and 1820-30 harden with increases in intensity. The implications of the results for recent models of low-mass X-ray binaries are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 308; 644-654
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  • 10
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    Spectral variability of Cygnus X-2 - Structure in the circumsource material (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Cygnus X-2 was observed during 13 separate pointings in the course of 1 yr by the Einstein monitor proportional counter. During one of these pointings the objective grating spectrometer was also used. It is found that the data from these observations are well fitted by single-component thermal bremsstrahlung models with temperatures ranging from 4-12 keV; however, two-component models, where one component is a blackbody, are not excluded. The X-ray light curve appears to be correlated with the 9.843 day optical period, possibly implying a partial eclipse of the X-ray source. During the high states there are irregular dips of up to 30 percent in intensity that last for 300-700 s. The high spectra resolution grating data were taken during one of the high states when these dips occurred, and it is possible to distinguish variable variable emission and absorption features due to Fe, O, and Ne. The picture of Cygnus X-2 is consistent with an intrinsic thermal source surrounded by a hot accretion disk corona. This model can be used to explain the high and low X-ray states, the variability within the states, and the intensity dips which occur in the high states.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 307; 698-710
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