Temat: DR - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Some Comments on p-Ps and Density Parameter
Autorzy:: Goworek, T.
Wawryszczuk, J.
Powiązania:: https://bibliotekanauki.pl/articles/1933488.pdf
Data publikacji:: 1995-07
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 36.10.Dr
Opis:: The constraint-free analysis of several representative positron lifetime spectra was performed with the resolution time of 144 ps. The role of p-Ps parameters in understanding of the positronium structure in solids is discussed.
Źródło:: Acta Physica Polonica A; 1995, 88, 1; 135-138
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 2.

Tytuł:: Pressure Effects in ortho-Positronium Annihilation
Autorzy:: Goworek, T.
Wawryszczuk, J.
Zaleski, R.
Powiązania:: https://bibliotekanauki.pl/articles/2042179.pdf
Data publikacji:: 2005-04
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 36.10.Dr
78.70.Bj
Opis:: A short review of experiments concerning the influence of high pressure on positron annihilation in molecular solids is given. To this kind of experiments belong e.g. pressure inhibition of positronium formation, pressure induced phase transitions, and free volume swelling in the media intercalated by high pressure gas.
Źródło:: Acta Physica Polonica A; 2005, 107, 4; 608-614
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 3.

Tytuł:: Positronium Formation in Solid Long-Chain Alkanes
Autorzy:: Zaleski, R.
Wawryszczuk, J.
Goworek, T.
Powiązania:: https://bibliotekanauki.pl/articles/2042188.pdf
Data publikacji:: 2005-04
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 36.10.Dr
78.70.Bj
Opis:: This paper represents a fragment of systematic studies on positron annihilation in solid saturated hydrocarbons (alkanes, paraffins) from C$\text{}_{17}$H$\text{}_{36}$ to C$\text{}_{30}$H$\text{}_{62}$. The Tao-Eldrup model and its extensions allow to identify the places in the crystalline structure where positronium is trapped, and estimate respective trap sizes. In the rigid phase I positronium locates mainly in two-dimensional empty spaces between the lamellae of crystal structure. Additional free volumes exist in high temperature phases due to appearance of n-alkane conformers representing a non-planar molecule distortion. The rise of ortho-positronium intensity with the sample irradiation dose, which was seen earlier in polymers, is observed also in n-alkanes. One can find similarities between the ortho-positronium annihilation in crystalline alkanes and polymers, like exponential character of that rise, and the trap bleaching by illumination. It confirms the same origin of the intensity growth, i.e. the accumulation of trapped electrons. Two kinds of electron traps were found. The time constant of electron accumulation in the traps depends on the carbon chain length and varies with temperature in different way for even- and odd-numbered alkanes.
Źródło:: Acta Physica Polonica A; 2005, 107, 4; 635-641
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 4.

Tytuł:: Ortho-Positronium in Alkanes under High Pressure
Autorzy:: Goworek, T.
Zgardzińska, B.
Powiązania:: https://bibliotekanauki.pl/articles/1812529.pdf
Data publikacji:: 2008-05
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 36.10.Dr
61.80.Fe
71.60.+z
78.70.Bj
Opis:: Phase transitions in n-alkanes were observed by using the positron annihilation lifetime method. In the case of alkanes, application of pressure is equivalent to temperature lowering (1 K corresponds to ≈4 MPa). When argon at high pressure penetrates the sample one observes a non-monotonous dependence of the melting point on pressure. This effect is observed also in even-numbered alkanes, in which there is no rotator phase.
Źródło:: Acta Physica Polonica A; 2008, 113, 5; 1379-1383
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 5.

Tytuł:: Positronium in Phase IV and Rotator Phase of Long-Chain Alkanes
Autorzy:: Zgardzińska, B.
Goworek, T.
Powiązania:: https://bibliotekanauki.pl/articles/1812555.pdf
Data publikacji:: 2008-05
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 36.10.Dr
61.80.Fe
71.60.+z
78.70.Bj
Opis:: Ortho-positronium lifetime and intensity was measured as a function of temperature and pressure for some n-alkanes in which so-called "phase IV" appears. This phase is characterized by slightly increased ortho-positronium lifetime compared to low-temperature phases. It was found that the effect of quenching positronium by light does not appear in all phases from phase IV upwards. The lifetime in the rotator phases becomes equal to that in liquids, and only the change of positronium formation intensity allows to detect the solid-liquid transition in positron lifetime measurements.
Źródło:: Acta Physica Polonica A; 2008, 113, 5; 1551-1555
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 6.

Tytuł:: Ortho-Positronium in Some n-Alkanes; Influence of Temperature and Pressure
Autorzy:: Zgardzińska, B.
Pietrow, M.
Goworek, T.
Wawryszczuk, J.
Powiązania:: https://bibliotekanauki.pl/articles/2047166.pdf
Data publikacji:: 2006-11
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 36.10.Dr
61.80.Fe
71.60.+z
78.70.Bj
Opis:: Positron lifetime spectra were measured for a series of odd-numbered n-alkanes from C$\text{}_{11}$H$\text{}_{24}$ to C$\text{}_{19}$H$\text{}_{40}$ as a function of temperature and pressure. The ortho-Ps lifetimes in the rotator phase and the increase in intensity at the transition to that phase can be explained by location of Ps in the vicinity of kink-type conformers. The relation between o-Ps lifetime and molecule length can be described in the framework of extended Tao-Eldrup model. One can eliminate the effect of intensity rise in time by sample illumination or by application of high pressure. A decrease in temperature by 1 K is equivalent to an increase in pressure by about 4 MPa.
Źródło:: Acta Physica Polonica A; 2006, 110, 5; 747-753
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 7.

Tytuł:: Positronium Formation with Trapped Electrons in n-Alkanes
Autorzy:: Zgardzińska, B.
Goworek, T.
Powiązania:: https://bibliotekanauki.pl/articles/1505332.pdf
Data publikacji:: 2011-03
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 36.10.Dr
36.20.Fz
61.80.-x
72.20.Jv
78.70.Bj
Opis:: Positronium (Ps) formation during self-irradiation by positrons was observed in n-alkanes of various carbon chain length. The rise of Ps intensity with time of irradiation is the result of positronium formation with trapped excess electrons. In the range T < 190 K the saturation value of positronium intensity changes with temperature mainly due to the change of positron mobility. With the increase of the irradiation dose the process of charging traps is slowing down and this effect is ruled mainly by interaction of excess electrons with ionization products during electron's migration to the traps.
Źródło:: Acta Physica Polonica A; 2011, 119, 3; 328-331
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Informacja

Wyszukujesz frazę "DR" wg kryterium: Temat

Źródło danych

Dostawca treści

Kolekcja

Rok wydania

Wydawca

Temat

Autor

Typ dokumentu

Język