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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 5510-5517 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The polarized reflection spectra of single crystals of PDA-CPDO [poly-1-(N-carbazolyl)penta-1, 3-diyn-5-ol], which are π conjugated between the side groups and the main chain, have been measured in the photon energy region from 1.38 to 32 eV for the first time with a polarized synchrotron radiation source. Absorption spectra have been calculated using the Kramers–Kronig relation. Transitions in the visible absorption spectrum, which have been previously attributed to an interband transition in a similar polydiacetylene, have been found to be highly dichroic with respect to the direction along the polymer backbone. The absorption spectrum in this region reveals two broad (ΔE(approximately-greater-than)0.4 eV) peaks at 1.9 and 2.7 eV with an almost equal absorption coefficient of 7.5×104 cm−1. The spectral features in the range from 3 to 8 eV result from electronic transitions of the carbazolyl side groups. A single broad (ΔE∼10 eV) absorption band observed at 18 eV is due to either transitions of σ electrons to higher σ* or π* states of the carbazolyl group, or to ionization processes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 1548-1551 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Interferometer measurements are extremely informative in shock wave studies allowing direct evaluations of the gas density. The primary goal of the work presented is to build a laser interferometer that meets the requirements of the highest possible simplicity, economy, convenience, and ease of construction. In our experiments, we used a low average power (10 mW) He–Ne laser without complication, expense, and environmental section. The He–Ne laser interferometer with the Michelson arrangement was used to measure the line-averaged gas densities of shock waves. Temporal and spatial measurements of the density were performed for shock wave developments from high-current pulse discharges. The shock wave propagates in the radial direction of the discharge channel with supersonic speed. The shock velocity, however, decreased from 2–0.5 km/s with the distance of the shock propagation. The width of the high density region, that is in the vicinity of the shock front was compressed from 3.5 to 1.8 mm according to the time variation of the discharge current. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 610-612 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For a long time, hexagonal diamond has been formed only by static and shock wave compression of well-crystallized graphites. Here, we demonstrate that cubic diamond loses its structure stability and transforms to hexagonal diamond in massive. This transformation has been completed in nanoseconds under a shock wave compression of cubic diamond, in which the shock pressure and temperature are only tens of giga pascal and hundreds of kelvin, thermodynamically being within the stability of cubic diamond. The formation of hexagonal diamond is interpreted as a direct transition (solid to solid) of cubic diamond by a kinetic mechanism due to the shear stress and enhanced temperature induced by the rapid shock wave compression. © 2002 American Institute of Physics.
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1111-1113 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the successful growth of high-quality InP/InGaAs double-heterojunction bipolar transistors with heavily Zn-doped base layers (p=4×1019 cm−3) using metalorganic vapor phase epitaxy. Interrupting the growth for 30 min after growing a heavily Si-doped subcollector (n=2×1019 cm−3) is shown to eliminate the excessive nonequilibrium group III interstitials that enhance abnormal Zn diffusivity in the subsequently grown base region. Gummel plots of the fabricated microwave transistors show that they have ideal turn-on characteristics in spite of having only 5-nm-thick undoped spacer layers inserted between the emitter and base. The transistors obtain a maximum oscillation frequency fmax of 178 GHz and a current gain cutoff frequency fT of 126 GHz.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 865-872 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Adhesion between thin Te-based alloy films and fluorocarbon polymer sublayers, prepared by sputtering or plasma polymerization, was investigated by observing the 1 μm-sized ablative hole opening process with a focused laser beam. Interpretations of the mechanisms for the change in energy required for the hole opening and pit geometry were based on the framework of studies of the ablative hole opening process for optical recording. Observations suggest that the molten material flow during the hole opening includes a ductile fracture and a viscous flow of the molten sublayer material as well as of active layer material. Adhesion acts as an energy barrier against the above mentioned flow of molten material during the hole opening process. Since the fluorocarbon films used in the present work had highly cross-linked structures, the adhesion was mainly dominated by the dynamic force of adhesion. Therefore, the hole opening process was mainly affected by the dynamic force of adhesion rather than the static force, which is dominated by the surface energy of the sublayer. There was a good correlation between the dynamic force of adhesion estimated by the peel-off strength and the concentrations of the -CF- and -C-CF- structures estimated from C1s spectra obtained by x-ray photoelectron spectroscopy. © 1995 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 2757-2760 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A broadband near-infrared pulse covering 700 nm around 2.4 μm has been generated by a dispersion-free parametric mixing in a KTiOPO4 crystal between the fundamental pulse (0.8 μm) from a Ti:sapphire regenerative amplifier and the white continuum pulse. It is tunable within the wavelength region of 1.7–2.9 μm. The comparison with a theoretical bandwidth indicates that the noncollinear phase matching plays a part for the spectral broadening.
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  • 7
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Hf-added FeRuGaSi alloy film has an amorphous structure in the as-deposited state and becomes nanocrystalline after annealing. Due to this structure change from crystalline to amorphous by the addition of Hf, soft magnetic degradation of the film deposited on the slant grooved substrate, which is necessary for the sophisticated embedded thin film (ETF) head structure, is greatly suppressed and the undesirable film stress is relieved. The FeRuGaSi-Hf alloy film has higher resistivity and permeability at high frequencies than those of sendust film, and the read/write characteristics of this alloy film show better performance than sendust film. © 1996 American Institute of Physics.
    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 81 (1997), S. 527-529 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The phase transformation of graphitelike BN (h-BN) to wurtzite-type high-pressure BN (w-BN) was investigated through shock-recovery techniques under quasihydrodynamic and nonhydrodynamic shock compressions and under various strain conditions. The experimental results support a diffusionless mechanism, by which the hydrodynamic c-axis compression of h-BN is preferred. This mechanism is topologically considered based on the relationship of crystal structures between h-BN and w-BN. The presence of deviatoric stress and strain depresses the yield of w-BN and the development of w-BN (100) relative to (002). © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic properties and magnetostriction in grain-oriented (TbxDy1−x)(Fe1−yMny)1.95 compounds with 0.3≤x≤0.5, 0≤y≤0.2 prepared by the Bridgman method have been investigated. It is confirmed that the Mn substitution not only lowers the spin reorientation temperature but also enhances λ〈100〉. This large λ〈100〉 is contradictory to the single-ion model. For Tb0.5Dy0.5 (Fe0.9Mn0.1)1.95 compound, no spin reorientation, which induces the sharp drop in the magnetostriction is seen in the temperature range from 77 to 400 K. In addition, by choosing the appropriate compressive stress, the quite excellent thermal stability and the large magnetostriction of 2000 ppm in the low applied field can be realized in the Tb0.5Dy0.5 (Fe0.9Mn0.1)1.95 compound. These features make Tb0.5Dy0.5 (Fe0.9Mn0.1)1.95 a promising material applicable to the various giant magnetostrictive actuators.
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 36-42 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A mm wave amplifier experiment on a free electron laser was performed using an intense, mildly relativistic electron beam (0.7–0.9 MeV) with a combination of a focusing planar wiggler and a weak additional axial magnetic field in the so-called "group 1'' region. A beam transport ratio of over 80%, through the whole wiggler length, was realized. In an amplification experiment, a spatial growth rate of 56 dB/m was obtained at a frequency of 45 GHz, and a power saturation was observed at a level of 6 MW, where the total gain was estimated to be 52 dB. It was shown that the off-axis component of the beam contributes considerably to the rf amplification in the focusing wiggler.
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