Autor: Liedke, M. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Positronium Formation in Nanostructured Metals
Autorzy:: Čížek, J.
Melikhova, O.
Hruška, P.
Vlček, M.
Anwand, W.
Liedke, M.
Novotný, M.
Bulíř, J.
Powiązania:: https://bibliotekanauki.pl/articles/1033937.pdf
Data publikacji:: 2017-11
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 78.70.Bj
41.75.Fr
36.10.Dr
Opis:: Positronium formation in Au films was studied using a magnetically guided continuous slow positron beam with variable energy. Black Au film with porous morphology was compared with conventional smooth Au film. In the smooth Au film positronium is formed on the film surface only. The black Au film exhibits porous sub-surface region containing micro-cavities interconnected with surface. Positronium is formed on inner surfaces of micro-cavities in the sub-surface region and travels through interconnected cavities towards the surface. 3-γ annihilation of ortho-positronium leaves a clear signature in two-dimensional coincidence Doppler broadening spectra. Measures of 3-γ annihilation contribution calculated from single γ-ray and coincidence Doppler broadening spectra were calculated and compared.
Źródło:: Acta Physica Polonica A; 2017, 132, 5; 1579-1584
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 2.

Tytuł:: Positronium Probing of Pores in Zirconia Nanopowders
Autorzy:: Prochazka, I.
Cizek, J.
Lukac, F.
Melikhova, O.
Hruska, P.
Anwand, W.
Liedke, M.
Konstantinova, T.
Danilenko, I.
Powiązania:: https://bibliotekanauki.pl/articles/1033930.pdf
Data publikacji:: 2017-11
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 81.07.Wx
61.46.Hk
78.70.Bj
Opis:: In the present paper, conventional positron lifetime measurements on selected zirconia-based nanopowders are reported. The nanopowders were doped with various metal cations (Y³⁺, Eu³⁺, Gd³⁺, Lu³⁺ and Mg²⁺). Lifetime experiments were conducted in air and supplemented with mass density measurements. In a range of lifetimes, from a few ns to ≈70 ns, up to two individual lifetime components could be identified. Such observations confirmed positronium (Ps) formation with subsequent ortho-Ps pick-off annihilation as well as the occurrence of pores of different size. Pore sizes were estimated using a shape-free model of the correlation between pore size and ortho-Ps lifetime. The origins of pores are discussed on the basis of the ortho-Ps data in combination with the results of mass density measurements.
Źródło:: Acta Physica Polonica A; 2017, 132, 5; 1564-1567
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 3.

Tytuł:: Adaptive Modulation Amplitude in 2D Spectral-Spatial EPR Imaging
Autorzy:: Czechowski, T.
Samolej, A.
Baranowski, M.
Boś-Liedke, A.
Chlewicki, W.
Jurga, J.
Tadyszak, K.
Powiązania:: https://bibliotekanauki.pl/articles/1030422.pdf
Data publikacji:: 2018-03
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 76.30.-v
42.30.Wb
75.20.-g
42.30.Va
Opis:: A study concerning the image quality in Electron Paramagnetic Resonance Imaging (EPRI) in 2D spectral-spatial (2D SSI) experiments is presented. The aim of the measurements is to improve the signal to noise ratio (SNR) of the projections by applying a more consciously selected modulation amplitude parameter. Data is gathered by applying three constant and one adaptive modulation amplitude. The three fixed modulation amplitudes values are leading to undermodulated (0.01 G), partially overmodulated (0.15 G) and fully overmodulated (0.65 G) projections. The study demonstrates the advantages of the adaptive method, which involves selecting different and dependent on cosine function modulation amplitudes for each projection. The study is performed on a phantom containing four tubes of LiPc and TCNQ, characterized by a different peak to peak linewidth and spin concentration.
Źródło:: Acta Physica Polonica A; 2018, 133, 3; 710-712
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

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