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1
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Phonon Images of Crystals for Different Sources

100%
Jasiukiewicz C., Paszkiewicz T.
Acta Physica Polonica A
|
1993
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vol. 84
|
issue 3
459-473
EN
The focusing patterns for energy and quasi-momentum are obtained for different types of phonon sources. We considered point and extended (Gaussian) sources and sources of monochromatic and Planckian phonons.
2
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Diffusive Propagation of Phonon Beams in Yttrium Aluminum Garnets Containing Substitutional Rare Earth Atoms

80%
Ivanov S., Khazanov E., Paszkiewicz T., Taranov A., Wilczyński M.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
381-386
EN
The diffusive maxima of phonon signals are studied for a number of solid solutions of rare earth atoms in yttrium aluminum garnets. The used exact formula for the diffusion constants allows for qualitative discussion of the obtained results. The established energy of phonons, forming the diffusive maximum of phonon signal of the temperature T_{H} arriving at the bolometer, ranges from 3.2k_{B}T_{H} to 4.2k_{B}T_{H}, which is in reasonable agreement with the existing estimations. The qualitative analysis allows us to estimate the contribution, made by the rare earth ions occupying the octahedral positions of the sixfold oxygen coordination, to the scattering of phonons due to lattice imperfections in yttrium aluminum garnets.
3
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Phonon Heat Conductivity of Garnets Containing Rare Earth Ions

80%
Bahuguna B., Painuli C., Indu B.
Acta Physica Polonica A
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1991
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vol. 80
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issue 4
527-543
EN
The phonon frequency line widths related to the phonon relaxation times is evaluated for impurity, anharmonic and interference scattering processes using double time temperature dependent Green's function method. The effects of force constant changes at impurity site and interference mode (new vibrational mode) on lattice thermal conductivity are the new features of the work. A few comments are made on the additivity of inverse relaxation times. The theory have been utilized to analyse the lattice thermal conductivity of ten synthetic aluminum garnets containing trivalent rare earth ions using Callaway's formula. The calculations show excellent agreements between theory and experiments.
4
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Response of Superconductor Bolometer to Phonon Fluxes

80%
Danilchenko B., Jasiukiewicz C., Paszkiewicz T., Wolski S.
Acta Physica Polonica A
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2003
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vol. 103
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issue 4
325-338
EN
A metallic film bolometer with heat capacity C is in contact with thermal bath and with crystalline specimen and is biased by a constant current I_b. The thermal contact of the bolometer is characterized by the thermal conductance G. The bolometer operates in the linear regime of dependence of resistance on temperature characterized by a constantα. Experiments which allow one to measureα, C, and G are proposed. The characteristic timeτ=C/G and characteristic current I_m=√{G/α} affect the effective relaxation rateΛ of the bolometer resistance R_b(t). The knowledge of the power W(t) absorbed by detector allows one to calculate R_b(t). The inverse problem of calculation of W(t) from known R_b(t) is also solved. The suitable algorithms are proposed. Deconvoluted absorbed power is obtained for experiments performed on GaAs and compared with phonoconductivity signal of two-dimensional electron gas structure as well as with results of Monte Carlo computer experiments.
5
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Images of the Response Signal of a 2D Gas of Carriers to a Pulsed Beam of 3D Phonons

80%
Jasiukiewicz C., Lehmann D., Paszkiewicz T.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
661-664
EN
The patterns for the time integrated drag current induced by a pulsed beam of bulk phonons in a 2D gas of charge carriers are calculated. A beam of Planckian phonons propagates in a GaAs crystal. We considered a 2D gas of electrons lying in a {001} plane and a 2D gas of holes lying in the {311} plane. Planckian phonons are radiated by an extended (Gaussian) source.
6
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Characterization of Metal Coated Diamond Crystallites by Combined Photoacoustic Effect and Photothermal Radiometry

70%
Delgadillo-Holtfort I., Gibkes J., Chirtoc M., Neubauer E., Bein B., Pelzl J.
Acta Physica Polonica A
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2008
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vol. 114
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issue 6A
A-57-A-61
EN
Photoacoustic effect and photothermal radiometry were applied to characterise the thermal properties of diamond crystallites which were coated by a Cu film, a Cr film and a Cr-Cu film. The Cu-coated diamond exhibits a considerable thermal barrier at the Cu-diamond interface which had disappeared for the crystallites with a thin bond Cr layer between diamond and Cu. The comparison of the responses of both measurement techniques reveals the non-negligible influence of the optical absorption in the visible and IR on the deduced thermal parameters.
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