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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 2490-2497 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have grown clean N-salicylideneaniline (SA) single crystals large enough for optical measurements. The photochromism of a SA single crystal is investigated at different optical polarizations. Based on theoretical calculations, the structure configurations of the SA molecules in the colored keto form are analyzed. When an ultraviolet (UV) light is irradiated on the sample at 200 K, about 40% of the keto form molecules are found to be in the cis configuration and about 60% of them in the trans configuration. The activation energies of the single crystal are obtained in different optical polarizations, and the energy-level schemes of the photochromic reactions are established. Investigation of a single crystal can provide us with new information on the photochromism of SA, because SA molecules are regularly arranged and the environment of each molecule is the same. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Susceptibility and high field magnetization have been measured for Y(Co1−xMx)2 (M=Al, Fe, and Ni). YCo2 exhibits a metamagnetic transition at 69 T. Ni doping in YCo2 increases the critical field (Bc), while Fe doping decreases it. These changes can be elucidated with the band picture of metamagnetism. Bc of YCo2 exhibits a positive shift proportional to the square of temperature. In the paramagnetic region of Y(Co1−xAlx)2 with x≤0.11, the susceptibility is enhanced with Al and a sharp metamagnetic transition with lower Bc is observed. The susceptibility becomes maximum at a finite temperature Tmax. Bc in the ground state is proportional to Tmax. These experimental results are discussed with a new theory based on a spin fluctuation model. The susceptibility and the metamagnetic transition are found to be very sensitive to pressure.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7221-7230 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electron, negative ion, and positive ion densities in a capacitively-coupled radio-frequency (rf, 13.56 MHz) SF6 plasma have been investigated as functions of the pressure (30–700 mTorr) and rf power. The decay of the charged particle densities in the afterglow has also been studied to obtain information about their kinetics. The electron density was determined by using a microwave cavity resonance technique. Negative ions were detected by measuring the density of photodetached electrons produced by pulsed laser irradiation of the plasma. The positive ion density was obtained from Langmuir probe measurements. At a rf power of 0.13 W/cm2 and at low pressures ((approximately-less-than)100 mTorr) the positive ion density, which is virtually equal to the negative ion density, is found to be larger than the electron density by a factor of a few hundred; the ion/electron density ratio increases with increasing pressure to reach a value of a few thousand at high pressures. Wavelength-dependent photodetachment measurements indicate that the dominant contribution to the photodetachment signal at 266 nm comes from F−, but F− is a minor negative-ion species with respect to the density; that is, the photodetachment efficiency for the dominant negative ion species (supposed to be SF−5) is low. The recombination rate constant for F− (supposedly with SF+5) is suggested to be an order of magnitude larger than that for the dominant ion species, the latter being estimated to be slightly smaller than 10−7 cm3 s−1. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 3856-3861 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact interferometer using a grating beamsplitter is reported. The phase of the interference signal was adjusted by using the moire effect of the gratings, so that a small optical path difference was compensated precisely by the magnified displacement of the grating. The optical system was analyzed theoretically on the basis of the Fourier optics. For the interferometric measurement in the microscopic region, a compact optical system was assembled from the microscopic objective and the 25-μm gratings. The characteristics of the proposed interferometer were investigated in the measurements of film thickness, piezoelectric vibration, and photoacoustic effect.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 1864-1868 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Barium-filled skutterudites BayCo4Sb12 with an anomalously large filling fraction of up to y=0.44 have been synthesized. The lattice parameters increase linearly with Ba content. Magnetic susceptibility data show that Ba0.44Co4Sb12 is paramagnetic, which implies that some of the Co atoms in BayCo4Sb12 have acquired a magnetic moment. The presence of the two different valence states of Co (Co3+ and Co2+) leads to the anomalously large barium filling fraction even without extra charge compensation. All samples show n-type conduction. The electrical conductivity increases with increasing the Ba filling fraction. The lattice thermal conductivity of BayCo4Sb12 is significantly depressed as compared to unfilled Co4Sb12. The dimensionless thermoelectric figure of merit, ZT, increases with increasing temperature reaching a maximum value of 1.1 for Ba0.24Co4Sb12 at 850 K. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 5927-5929 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An XeCl excimer laser was operated at the high repetition rate of 2.5 kHz, which can circulate the laser gas uniformly and efficiently. The characteristics of the gas flow rate and the average laser power versus the repetition rate were investigated in both He and Ne buffer gas mixtures. In He buffer gas, the average laser power saturates at 1.3 kHz and, thereafter, drops abruptly. On the other hand, stable operation at the highest repetition rate, 2.5 kHz, has been attained in Ne buffer at a gas flow rate of 54 m/s with an average laser power of 87 W.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5956-5958 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The proton spin-lattice relaxation rate 1/T1 has been measured in the two compounds Ni(C2H8N2)2NO2 (ClO4) (NENP) and [Ni(NO2)3N(CH3)4] (TMNIN), which provide good examples of S=1 antiferromagnetic chains. Both the field H and the temperature dependencies are well analyzed in the framework of the Haldane conjecture. The prediction of a mode whose energy decreases with H is confirmed. The energy damping of this mode is observed to be also reduced by H. For both compounds, a possible energy renormalization is suggested as H approaches the critical field, where the spin system is expected to recover a magnetic behavior.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 1518-1521 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nitrogen has been introduced in the preparation of hydrogenated amorphous silicon carbon alloy films by magnetron sputtering of silicon in a methane-argon gas mixture. The partial pressure of nitrogen was changed, and its effects on the structural, optical, electrical, and optoelectronic properties of the deposited films were investigated. The SiN bond becomes predominant with increasing partial pressure of nitrogen pN above 10%, at which the optical band gap is rapidly increased. The concentration of silicon and carbon in the films remained almost unchanged by changing pN up to 20%. It was found that the photoconductivity is also almost unchanged up to 20%, while the optical band gap is increased. This indicates that the photoconductivity is improved over a wider optical band gap, as compared with previous studies when the optical band gap was changed by changing deposition conditions but without introducing nitrogen.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 243-245 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bi-Ti-O oxide thin films were prepared on a sapphire single-crystal substrate by electron cyclotron resonance (ECR) plasma sputtering. The target used was a sintered Bi4Ti3O12(BIT) and the substrate was controlled in the temperature range 400–640 °C(Tsub). The film sputtered at Tsub=400 °C was a pyrochlore type oxide(Bi2Ti2O7), which changed to a Bi4Ti3O12 oxide in the polycrystalline state at 500 °C and in the single crystalline state at 640 °C. In the film sputtered at 640 °C, the (001) plane of the Bi4Ti3O12 grew parallel to the (112¯0) and (11¯02) planes of the sapphire substrate, and the (104) plane of Bi4Ti3O12 grew parallel to the (0001) plane of the sapphire substrate. The deposition rate was about 200 A(ring)/min independent of the sputtering conditions.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetization, magnetic susceptibility, and crystal structure are investigated on the ternary chromium arsenides CrM'As (M'=Ru,Rh,Pd) and ternary manganese phosphides and arsenides MnM'P(M'=Rh,Pd) and MnM'As(M'=Ru,Pd). MnRhP, MnRuAs, and MnPdAs are ferromagnets with a Curie temperature of Tc=401, 496, and 210 K, respectively. CrRhAs is an antiferromagnet with a Néel temperature of TN=165 K. MnPdP and CrPdAs show spin-glass-like freezing. A magnetic order-order transition is observed for CrRuAs. Susceptibility χ versus temperature curves are well expressed by a formula χ =C'/(T − θ'P)γ for all present compounds. The values of γ are about 3/2 for manganese compounds and CrPdAs, and about 1/2 for CrRuAs and CrRhAs.
    Type of Medium: Electronic Resource
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