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  • 1
    ISSN: 1520-6041
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 182 (1958), S. 599-599 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The complete expression for the rate of fading due to the Faraday effect is : h, = 2-36 x 104./-2.£ | (cos 0 sec 8) f N(h)dh + dt (_ ot J (cos 0 sec 8) °. N(h8) 1 radians sec.-1 dr J where f is the transmitted frequency in c./s., B the Earth s magnetic field in gauss, the angle ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 181 (1958), S. 1392-1393 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] To obtain an unambiguous result, two closely spaced frequencies were used by Browne et cd.1 and by Evans2, who determined the angle between the planes of polarization of the two waves. The electron content can also be obtained by using a single frequency sufficiently high (400 Mc./s. or above) so ...
    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 89 (2001), S. 4503-4511 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Charged closed-cell polypropylene polymer foams are highly sensitive and broadband piezoelectric materials with a quasistatic piezoelectric d33 coefficient about 250 pC/N and a dynamic d33 coefficient of 140 pC/N at 600 kHz. The piezoelectric coefficient is much larger than that of ferroelectric polymers, like polyvinylidene fluoride, and compares favorably with ferroelectric ceramics, such as lead zirconate titanate. The pyroelectric coefficient p3=0.25 μC/m2 K is small in comparison to ferroelectric polymers and ferroelectric ceramics. The low density, small pyroelectric coefficient and high piezoelectric sensitivity make charged polymer foams attractive for a wide range of sensor and transducer applications in acoustics, air-borne ultrasound, medical diagnostics, and nondestructive testing. © 2001 American Institute of Physics.
    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 72 (1992), S. 5363-5370 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For the investigation of polarization distributions in pyroelectric materials, the laser intensity modulation method (LIMM), which is based on thermal waves, is widely used. With this method, the sample under investigation is heated by the absorption of intensity modulated light at one surface, while the pyroelectric current is measured. The thermal excitation generates a thermal wave penetrating into the sample. The penetration depth is varied with the modulation frequency. A new procedure for the reconstruction of the polarization distribution from a measured pyroelectric current spectrum is introduced. This procedure is especially well suited for polarization probing near the sample surface. An approximation for the polarization distribution is calculated from a measured pyroelectric spectrum in a very simple and direct way, avoiding mathematical instabilities. The calculation can be performed during the measurement of a pyroelectric current spectrum. This makes LIMM an on-line procedure. The new technique of analysis is applied to the measurement of thin depolarized layers near the surface of homogeneously poled ferroelectric polymer films.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2941-2943 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pulsed-laser deposited (PLD) polytetrafluoroethylene (Teflon-PTFE) films from press-sintered powder targets are found to be highly crystalline, with spherulite sizes adjustable over more than one order of magnitude by suitable thermal annealing. Films with large spherulites show an excellent charge stability, comparable and even superior to commercially available Teflon-PTFE foils. PLD-PTFE enlarges the family of Teflon materials and may thus become interesting for potential miniaturized electret devices. © 1998 American Institute of Physics.
    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 75 (1994), S. 5306-5315 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A compact and easy-to-use experimental set-up for pyroelectric investigations of poled nonlinear optical (NLO) polymers is reported. The arrangement allows for the investigation of the NLO dipole relaxation under isothermal or nonisothermal (e.g., linear heating of the polymer) conditions. Furthermore, polarization patterns in the plane of a polymer film and polarization profiles in its thickness direction can be measured in the same experimental set-up. In waveguide structures, it is possible to determine the thicknesses of an active guiding layer and of the claddings, if their thermal parameters are known. The isothermal pyroelectric relaxation data are discussed within the framework of phenomenological relaxation functions. It is found that they cannot be fitted with the stretched exponential function, a result which is in agreement with broadband dielectric-relaxation measurements. Pyroelectric experiments are the only method for investigations of all these problems in one and the same easy-to-use set-up.
    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 80 (1996), S. 5531-5558 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A brief survey of the electrical and optical properties of poled polymer electrets for sensors and photonic applications is given. Semicrystalline ferroelectric polymers are highly suitable for piezo- and pyroelectric applications, while amorphous polymers containing molecular dipoles with acceptor and donor groups linked by delocalized π electrons (A-π-D) are interesting for photonic applications. The large variety of poling techniques, such as electrode, corona, electron-beam, and photothermal poling, is discussed in detail together with specifically developed poling techniques for ferroelectric or amorphous polymers. Methods for the experimental investigation of the polar order are based on the piezo-, and pyroelectric effect, birefringence, the electro-optical effect and second-harmonic generation. Newly developed thermal analysis techniques and dipole relaxation spectroscopies complement traditional techniques, such as thermally stimulated depolarization and broadband linear and nonlinear dielectric relaxation spectroscopy. The compatibility of polymers with semiconductor technology is illustrated with selected applications in hybrid integrated thermal and acoustical imaging devices, electro-optical modulators and second-harmonic generators. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 6361-6367 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method is described that enables the simultaneous or consecutive determination of the specific heat, the thermal diffusivity, the dielectric constant, and the pyroelectric coefficient of thin pyroelectric films. The sample is heated by the absorption of intensity modulated light at one surface. The pyroelectric current and the transient temperatures of the sample surfaces are recorded as a function of the modulation frequency of the chopped light. The transient temperature recording is performed via thin-film bolometers. Analysis procedures for the determination of the specific heat, the thermal diffusivity, and the spatially varying pyroelectric coefficient are introduced and discussed. A simulation of the performance of integrated pyroelectric ir sensors on silicon chips is performed by a coupling of the pyroelectric material to a heat sink. It is shown that the response of pyroelectric ir sensors integrated on silicon chips is influenced by heat wave interference effects. Experimental results are given using thin pyroelectric PVDF films. It is shown that the use of pyroelectric polymers for integrated pyroelectric sensors is a good choice, due to their low thermal conductivity.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2759-2767 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: System functions of many linear physical systems or autocorrelation functions of their output signals are often a sum of relaxator terms with different relaxation times and amplitudes. In the time domain a superposition of exponential decays e−γt is observed, while in the frequency domain a sum of relaxator terms of structure 1/(γ+iω) is measured. Thus, the response is either the Laplace transform of the system function or its Stieltjes transform, respectively. In both cases it is the task of an analyst to gain the relaxation times and weights from the measured signal. An exact reconstruction of the system function is limited by the noise, measuring time, and number of points measured. In this paper procedures for the approximate reconstruction of the system function are introduced. The equivalence of most of them is shown and their properties are discussed. An expression for the limit of resolution is derived for a given signal-to-noise ratio. The results are applicable to experimental data from various physical systems. For illustration the autocorrelation function of the light scattered from polymer solutions and the response of photoconductors are used.
    Type of Medium: Electronic Resource
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