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  • Electronic Resource  (85)
  • 2000-2004  (13)
  • 1995-1999  (50)
  • 1970-1974  (22)
  • 1
    Electronic Resource
    Electronic Resource
    A study of a microwave cavity tuned oscillator (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 3631-3632 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: By using a microwave cavity tuned oscillator (MCTO), the relative dielectric constant ε of nonpolar dielectric fluid was measured with high accuracy. The theory of this technique was studied in detail. A new formula for evaluating the uncertainty of the measured ε was derived. From the formula, we have found that MCTO has a locking characteristic and therefore only operates in certain discrete regions. We have also found that a higher resonant frequency f of the MCTO, a longer delay time of the delay line, and a higher quality factor of the cavity Q lead to a higher accuracy of the measurement. When the values of the above parameters are taken properly, the uncertainty measured ε by the MCTO may become as small as an order of 10−5. The ε of saturated liquid nitrogen was measured by this approach and the experimental results agree very well with the values calculated by our formula. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147127
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  • 2
    Electronic Resource
    Electronic Resource
    Distribution of Three Nicotinic Receptor α4 mRNA Transcripts in Rat Brain: Selective Regulation by Nicotine Administration (1996)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 66 (1996), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Northern blot analysis determined whether multiple α4 transcripts for neuronal nicotinic receptors in rat brain could be detected as distinct bands. When poly(A)+ RNA was isolated from brain regions and hybridized with a Hinfl fragment of α4-1 cDNA containing a sequence shared by both α4-1 and α4-2, but little homology with other α or β subunits, bands at 6.0, 4.6, and 2.6 kb were obtained. When a Taql fragment with selectivity for α4-1 was used, a single band was present at 6.0 kb. The 6.0-kb band was least abundant in all brain regions; the 2.6-kb band was most abundant in frontal cortex, hippocampus, striatum, basal forebrain, and thalamus, whereas the 4.6-kb band was most abundant in midbrain and cerebellum. Nicotine (3.6 µmol/kg, s.c., twice daily) increased the abundance of the 4.6-kb transcript in frontal cortex significantly by 28% following 2.5 days of injections; the 6.0- and 2.6-kb transcripts were unchanged. Nicotine did not affect α4 transcripts in other brain regions. Results suggest that increased mRNA levels may mediate the nicotine-induced up-regulation of receptors in cerebral cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1996.66031326.x
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  • 3
    Electronic Resource
    Electronic Resource
    Nonradiative recombination at GaAs homointerfaces fabricated using an As cap deposition/removal process (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 3163-3165 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaAs homointerfaces have been grown by molecular beam epitaxy using the steps of GaAs growth, As cap deposition, wafer storage, thermal desorption of the As cap, and GaAs overgrowth. As cap layers with a thickness of up to 7.8 μm were deposited and the wafers were stored for 3–7 days in ultrahigh vacuum (UHV) or under atmospheric conditions. Nonradiative recombination originating from the GaAs homointerface of wafers stored in UHV could not be detected (interface recombination velocity S(very-much-less-than)1000 cm/s), however, significant nonradiative recombination (S=104–105 cm/s) was found for all GaAs homointerfaces where wafer storage occurred under atmospheric conditions. This result demonstrates that the As cap deposition/removal process is inadequate for GaAs surface protection in a fabrication facility. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121580
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  • 4
    Electronic Resource
    Electronic Resource
    The larger polar Kerr rotation of Fe-Si alloy films and their magnetic properties (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1383-1384 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure, magnetic properties and polar Kerr effects of Fe100−xSix (0≤x≤70) alloy films prepared by ion-beam co-sputtering were studied. We find that the saturation magnetization of these films decreases with increasing x, and a plateau of constant magnetization occurs as 22≤x≤28. Their polar Kerr rotation θk decreases with increasing x as x≤16.2 and x≥30, but increases with increasing x as 20≤x≤28. In the measuring wavelength range of 400–800 nm, the θk of Fe72Si28 film is 40% to 50% larger than that of pure Fe film. We think that amorphization may play an important role in enlarging the polar Kerr rotation of these films. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121062
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  • 5
    Electronic Resource
    Electronic Resource
    High-brightness blue and green light-emitting diodes (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 115-117 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report high-brightness blue and green light-emitting diodes (LEDs) based on II–VI heterostructures grown by molecular beam epitaxy on ZnSe substrates. The devices consist of a 2–3 μm thick layer of n-type ZnSe:Cl, a ∼0.1 μm thick active region of Zn0.9Cd0.1Se (blue) or ZnTe0.1Se0.9 (green), and a 1.0 μm thick p-type ZnSe:N layer. The blue LEDs produce 327 μW (10 mA, 3.2 V), with the light output sharply peaked at 489 nm, and exhibit an external quantum efficiency of 1.3%. The green LEDs produce 1.3 mW (10 mA, 3.2 V) peaked at 512 nm, corresponding to an external quantum efficiency of 5.3%. In terms of photometric units, the luminous performance (luminous efficiency) of the devices is 1.6 lm/W (blue) and 17 lm/W (green), respectively, when operated at 10 mA. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113534
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  • 6
    Electronic Resource
    Electronic Resource
    Efficient up-conversion fluorescence in charge transfer compound crystal (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2777-2779 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A series of new intramolecular charge transfer compounds with absorption bands in shorter wavelengths have been synthesized. Bright visible light emits from the crystals of these new compounds under infrared pulsed laser pumping. The spectral and pump density dependent properties demonstrate that some of the emissions are up-conversion fluorescence due to two photon absorption. The fluorescent yields of one- and two-photon absorption are in the same order at high pump density. This work demonstrates that these new intramolecular charge transfer crystals are good candidates for nonlinear optical materials. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113472
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  • 7
    Electronic Resource
    Electronic Resource
    Rapid cooling and magnetic field-induced cooperative effect for the metastable quintet state in a spin crossover complex (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 4029-4031 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Our study shows that metastable quintet state of spin crossover complex [Fe(dpp)2(NCS)2]⋅py (dpp=dipyrido[3,2-a:2′,3′-c] phenazine, py=pyridine) at low temperatures may be realized by a rapid cooling. The relaxation from quintet state to singlet spin at low temperatures depends on the both of time and previous history of the sample. The U-shaped dents of the magnetic effective moment depending on the temperature after initial rapid zero-field cooling indicate an obvious affection of magnetic field to the realization of singlet state in the transition range. The observations for this sample are indeed consistent with the fact that cooperative effects play a very important role in the spin transition. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123250
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  • 8
    Electronic Resource
    Electronic Resource
    Graphitization of nanodiamond powder annealed in argon ambient (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3651-3653 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nanodiamond powder was annealed at each of the following temperatures: 300, 600, 800, 1000, and 1150 °C, for an hour in flowing argon ambient. The variations of x-ray diffraction patterns and Raman spectra of the powder with different annealing temperatures were studied. While being annealed at temperatures higher than 800 °C, the powder can undergo a phase-transition process from cubic diamond to graphite. In addition, the size of nanodiamond crystallites decreased from ∼50 to ∼25 Å. The physical mechanism responsible for the variation in Raman spectra is discussed using a phonon-confinement model. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123211
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  • 9
    Electronic Resource
    Electronic Resource
    An initiation mechanism of thermal instability of a metal-diamond-vacuum field emission regime (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 2383-2385 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An analysis is carried out of the physical origin of thermal instability that can trigger a catastrophic vacuum breakdown event in vacuum microelectronic devices based on flat diamond emitters. The temperature rise in a diamond film will enhance internal field emission across metal–diamond interface. This effect can lead to a regenerative process that can initiate a breakdown event at temperature lower than the melting point of an emitter. A set of equations has been developed. These theoretical findings are successfully applied to explain the instability of field emission from the nondoped diamond films. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125121
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  • 10
    Electronic Resource
    Electronic Resource
    Epitaxial PbZr.52Ti.48O3 films on SrTiO3/(001)Si substrates deposited by sol–gel method (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 1062-1064 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the sol–gel deposition and characterization of high-quality, epitaxial films of PbZr.52Ti.48O3 (PZT) on (001)Si substrates, with a thickness range of 400 Å to 1 μm. The epitaxial growth of PZT on (001)Si is achieved using a thin template layer of SrTiO3, grown by molecular-beam epitaxy. The sol–gel PZT films have a typical surface roughness of 5 Å and exhibit well defined reflective high-energy electron diffraction patterns characteristic of smooth, epitaxial films. Using high-resolution transmission electron microscopy and double-crystal x-ray diffraction, we find that the PZT films are oriented with the c axis normal to the (001)Si plane and with the a axis lying along 〈110〉Si direction. Finally, we measure the electromechanical coupling coefficients and the surface acoustic wave velocities for our films as a function of thickness and compare our experimental data to previously published theoretical values for this system. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1498006
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