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  • 1990-1994  (5)
  • 1985-1989  (2)
  • 1970-1974  (1)
  • 1910-1914  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6537-6539 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Elastic anomalies in an Fe75Pt25 single crystal have been investigated by ultrasonic pulse echo and inelastic neutron scattering measurements in the temperature range 200 to 800 K. The single crystal which was grown by the Bridgman–Stockbarger process undergoes a magnetic transition at Tc = 370 K and a martensitic transformation at Ms = 200 K corresponding to a degree of order of S=0.7. Both ultrasonics and neutron scattering reveal a softening of the transverse modes below Tc. The excess elastic constants obey an M2 law as expected from a local magnetoelastic interaction model. The longitudinal ultrasonic velocities already start to soften at 700 K whereas the neutron data for the same acoustic branch do not show any anomaly down to 200 K. The observed q dependences of the acoustic branches point towards a softening confined to the very center of the Brillouin zone.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6069-6071 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Triple-axis inelastic polarized neutron measurements have been performed as a function of temperature on a single crystal of the Invar alloy Fe65Ni35 to distinguish longitudinal from transverse magnetic excitations in the magnetically ordered phase. Well below the Curie temperature of 501 K the magnetic excitation spectrum is dominated by conventional transverse spin-wave excitations, which in fact follow the predictions of spin-wave theory very well. In particular, we find no evidence for propagating longitudinal excitations in this system, in sharp contrast to the behavior observed in the amorphous Invar Fe86B14 material as well as the non-Invar amorphous system Fe40Ni40P14B6.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed inelastic neutron scattering measurements of the long-wavelength spin wave excitations of both ordered and disordered Fe72Pt28 single crystals below their critical temperatures, TC=510 and 375 K, respectively. The spin waves followed the expected E=Dq2 dependence, and the temperature-dependent spin stiffness D decreased as (T/TC)5/2, as expected for an isotropic ferromagnet. The extrapolated zero-temperature spin stiffness was D=98(4) meV A(ring)2 and 107(1) meV A(ring)2 for the disordered and ordered alloy, respectively. These values are significantly higher than the zero-temperature stiffness as determined by magnetization measurements.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3933-3933 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Most of the metallic rare-earth chalcogenides of RE3X4 type, where X stands for S, Se, Te, show marked elastic anomalies which appear either in conjunction with a structural transformation or with a magnetic ordering transition. In this contribution we report on results obtained from Nd3Se4 where the elastic constants display a particular magnetic field dependence. Single crystals were grown by a Bridgman–Stockbarger method and the three cubic elastic constants were measured by ultrasonic techniques as function of temperature and in an external magnetic field. The occurrence of magnetic ordering was proved independently by susceptibility measurements. Nd3Se4 has been found to order ferromagnetically at Tc =52 K. In the absence of an external magnetic field approaching Tc from above, the shear elastic constants (C11−C12)/2 softens by about 40%. Below Tc the elastic constants harden again where the increment of C11 follows the Brillouin function of the magnetization. An external magnetic field parallel to the propagation direction of the sound waves affects the elastic anomalies in the paramagnetic as well as in the ferromagnetic phase. Above Tc the sound velocities exhibit a H2 field dependence, as is expected from a magnetoelastic coupling mechanism. At temperatures smaller Tc the field-dependent elastic anomalies are related to the hysteresis loop M(H). The change of the elastic constants as a function of the magnetic field is proportional to the field derivative dM/dH. The coupling coefficient has an opposite sign for the C44 and (C11−C12)/2 shear elastic constants.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1265-1268 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The HP 4274A and HP 4275A LCR meters are widely used in the fields of semiconductor device characterization and component test. A bias voltage can be applied to the test samples either from an external power supply or from the built-in HP-IB controllable voltage source. The total series resistance of the bias filtering circuit should be in the range of about 100 Ω (HP 4275A). Detailed measurements and checking the measuring circuit diagrams revealed that the effective series resistance can be much higher, depending on the measuring range of the bridge. Therefore, admittance measurements on low-ohmic samples, especially Schottky or pn junctions under heavy forward bias conditions, are seriously affected by bias voltage reduction between the front HI/LOW terminals. Thus, e.g., a reduced apparent capacitance is measured. Consequently, the doping concentration near the pn junction will be determined erroneously. To avoid these effects, a bias regulating circuit is inserted into the LCR meters to guarantee the feedthrough of the bias voltage without any attenuation. Examples of admittance vs frequency and doping profiles near the pn junction of quaternary (Ga0.046In0.954As0.1P0.9) diodes are given for explanation.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detector stage comprising a photodiode, a field-effect transistor, and a load resistor, and a wavelength demultiplexer have been monolithically integrated in the GaInAsP/InP material system. Chips were mounted into complete modules and operated in a 1.3 μm/1.55 μm bidirectional transmission link. At 576 Mbit/s and 10−9 bit error rate the sensitivity of the module was −21 dBm, while the intrinsic sensitivity of the receiver was determined to be −28 dBm.
    Type of Medium: Electronic Resource
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  • 7
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    Unknown
    Wiesbaden : Periodicals Archive Online (PAO)
    Geographische Zeitschrift. 19:4 (1913:Apr. 17) 228 
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 101 (1970), S. 362-374 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Contrary to thebaine base (1), which on treatment with bromoacetamide in anhydrous methanol is known to give 14-bromocodeinone dimethylketal (2 a), thebaine metho methylsulfate yields the metho salt of the isomeric 7-bromoneopinone dimethylketal (3 a). From the ketone methoperchlorate (3 b) on heating with water or in buffered solution the methoperchlorate of 7-oxo-thebainone (6) and HBr are formed. However, in strongly acidic solutions3 a as well as3 b give 7-bromo-7,8-dehydrometathebainone methoperchlorate (7 a), isomeric with3 b, a key intermediate, from which the diketone methoperchlorates8 a and8 b, the methine9, the methyl enolates10 a and10 b, and finally the 7-bromo-morphothebaine derivatives12 a–d and13 can be obtained.
    Notes: Zusammenfassung Thebain-metho-methylsulfat liefert mit Bromacetamid in absol. Methanol das Methosalz des 7-Brom-neopinon-dimethylketals (3 a) im Gegensatz zur Thebain-Base (1), die das isomere 14-Bromcodeinon-dimethylketal (2 a) ergibt. Aus dem Ketonmethoperchlorat3 b entstehen beim Erwärmen in Wasser oder gepufferter Lösung das Methoperchlorat des 7-Oxo-thebainons (6) und HBr. In stark saurer Lösung hingegen gelangt man von3 a oder3 b zu dem mit3 b isomeren 7-Brom-7,8-dehydrometathebainon-methoperchlorat (7 a). Von diesem ausgehend, wurden die Diketon-methoperchlorate8 a und8 b sowie das Methin9 gewonnen, weiters auch die entsprechenden Methylenolate10 a und10 b. Über7 a führte auch der Weg zu den 7-Brom-morphothebain-derivaten12 a–d und13.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 50 (1911), S. 736-740 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 796-802 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The corrosion of optical glasses often reduces the utility of uncoated glasses as well as the adhesion of resistive coatings deposited onto corroded glasses. Photoelectron spectroscopy (XPS) was applied to study glass surfaces with respect to their surface corrosion. In particular, leaching by the influence of polish slurries, pure water, air and even residual gases inside a vacuum device was studied in detail. Pure quartz glass and different sodium and barium silicate glasses were broken in ultrahigh vacuum (4 × 10-10 mbar) for the determination of sensitivity factors of the different XPS signals. It was found that a quantitative determination of the surface composition of corroded and leached layers is possible by determination of the intensities of the XPS O 1s, Si 2p, Si 2s, B 1s, Na 1s, Na 2s, Na 2p, Ba 3d and Ba 4d signals. After leaching in aqueous solutions, the barium is exchanged by hydrogen via an interdiffusion mechanism, resulting in an enrichment of different hydrogen bonds (H2O/H3O+, OH-, ≡Si—O—H) in the leached layer. An iterative algorithm is shown, which allows, in addition to the content of all other elements, the hydrogen content to be determined quantitatively in the leached layers. Furthermore, the calculation of the density of surface layers becomes possible. For an exact analysis of the leached layers the intensity loss by contamination layers is considered and the calculated density is used to perform matrix-dependent intensity corrections for the attenuation length.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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