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Wyszukujesz frazę "paramagnetic molecule" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Ortho-para spin conversion of Ps by paramagnetic O2 dissolved in organic compounds
Autorzy:
Zgardzińska, B.
Białko, W.
Jasińska, B.
Powiązania:
https://bibliotekanauki.pl/articles/971542.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
alcohols
cyclohexane
isooctane
n-alkanes
ortho-para conversion
paramagnetic molecule
Opis:
The o-Ps mean lifetime value in liquids decreases in the presence of the paramagnetic oxygen molecules via the ortho-para conversion process. This effect was observed for several organic samples composed of carbon and hydrogen atoms differing in the arrangement of atoms forming the molecule, e.g. n-alkanes, alcohols, branched isomer of alkane, cycloalkane. The usually observed tendency of the o-Ps lifetime value to be an increasing function of temperature (in the case of measurements performed in vacuum) changes to a decreasing one in the presence of O2 dissolved in the sample. The difference between the o-Ps lifetimes measured in samples in vacuum and in the presence of O2 increases with the distance from the melting point. The ortho-para constant rate λconv was estimated to be ~130 μs–1 at 300 K for three compounds investigated.
Źródło:
Nukleonika; 2015, 60, No. 4, part 1; 801-804
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interaction of diatomic molecules with nickel ions inside the channels of high silica zeolites : an EPR and DFT study
Autorzy:
Mazur, T.
Podolska, K.
Pietrzyk, P.
Sojka, Z.
Powiązania:
https://bibliotekanauki.pl/articles/147105.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
electron paramagnetic resonance (EPR) spectroscopy
g-tensor
nickel
zeolite
small molecule activation
Opis:
Interaction of CO, NO, and O2 diatomics with NiII and NiI ions dispersed in ZSM-5 zeolite was investigated by electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT) modelling. The resulting adducts NiI-CO, NiII-NO, and NiI-O2 were identified based on g-tensor parameters, obtained by computer fitting of the powder EPR spectra, and next ascertained by parallel relativistic DFT calculations of the corresponding g-tensor values. The structures of the NiI-CO, NiII-NO, and NiI-O2 complexes were obtained by geometry optimization with the Kohn- -Sham method. Binding of the diatomics was discussed in terms of the spin-pairing and electron density transfer events. Interaction of CO with NiI cations led to the pronounced change in the coordination and electronic structure of the NiI center, however, no redox processes were observed in agreement with the “innocent” nature of CO as a ligand. On the contrary, strong electron and spin density redistribution was observed upon NO and O2 interaction (“non-innocent ligands”) leading to the formation of the bound nitrosonium NOδ+ and superoxo O2 – species, respectively.
Źródło:
Nukleonika; 2013, 58, 3; 351-357
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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