Study on the effect of atmospheric gases adsorbed in MnFe2O4/MCM-41 nanocomposite on ortho-positronium annihilation
In this paper, results of positron annihilation lifetime spectroscopy (PALS) studies of MnFe2O4/MCM-41 nanocomposites in N2 and O2 atmosphere have been presented. In particular, the influence of manganese ferrite loading and gas filling on pick-off ortho-positronium (o-Ps) annihilation processes in...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Sciendo
2015-12-01
|
| Series: | Nukleonika |
| Subjects: | |
| Online Access: | http://www.degruyter.com/view/j/nuka.2015.60.issue-4/nuka-2015-0141/nuka-2015-0141.xml?format=INT |
| _version_ | 1798031453236232192 |
|---|---|
| author | Wiertel Marek Surowiec Zbigniew Budzyński Mieczysław Gac Wojciech |
| author_facet | Wiertel Marek Surowiec Zbigniew Budzyński Mieczysław Gac Wojciech |
| author_sort | Wiertel Marek |
| collection | DOAJ |
| description | In this paper, results of positron annihilation lifetime spectroscopy (PALS) studies of MnFe2O4/MCM-41 nanocomposites in N2 and O2 atmosphere have been presented. In particular, the influence of manganese ferrite loading and gas filling on pick-off ortho-positronium (o-Ps) annihilation processes in the investigated samples was a point of interest. Disappearance of the longest-lived o-Ps component with τ5 present in the PAL spectrum of initial MCM-41 mesoporous material in the PAL spectra of MnFe2O4-impregnated MCM-41 measured in vacuum is a result of either a strong chemical o-Ps quenching or the Ps inhibition effects. The intensity I4 of the medium-lived component initially increases, reaching a maximum value for the sample with minimum manganese ferrite content, and then decreases monotonically. Analogous dependence for the intensity I3 of the shortest-lived component shows a maximum at higher MnFe2O4 content. Filling of open pores present in the studied nanocomposites by N2 or O2 at ambient pressure causes partial reappearance of the τ4 and τ5 components, except a sample with maximum ferrite content. The lifetimes of these components measured in O2 are shortened in comparison to that observed in N2 because of paramagnetic quenching. Anti-inhibition and anti-quenching effects of atmospheric gases observed in the MnFe2O4/MCM-41 samples are a result of neutralization of some surface active centers acting as inhibitors and weakening of pick-off annihilation mechanism, respectively. |
| first_indexed | 2024-04-11T19:57:46Z |
| format | Article |
| id | doaj.art-29df180e733b453581963a3c89369ef4 |
| institution | Directory Open Access Journal |
| issn | 0029-5922 |
| language | English |
| last_indexed | 2024-04-11T19:57:46Z |
| publishDate | 2015-12-01 |
| publisher | Sciendo |
| record_format | Article |
| series | Nukleonika |
| spelling | doaj.art-29df180e733b453581963a3c89369ef42022-12-22T04:05:52ZengSciendoNukleonika0029-59222015-12-0160478378710.1515/nuka-2015-0141nuka-2015-0141Study on the effect of atmospheric gases adsorbed in MnFe2O4/MCM-41 nanocomposite on ortho-positronium annihilationWiertel Marek0Surowiec Zbigniew1Budzyński Mieczysław2Gac Wojciech3Department of Nuclear Methods, Institute of Physics, M. Curie-Skłodowska University, 1 M. Curie-Skłodowskiej Sq., 20-031 Lublin, Poland, Tel.: +48 81 537 6220, Fax: +48 537 619Department of Nuclear Methods, Institute of Physics, M. Curie-Skłodowska University, 1 M. Curie-Skłodowskiej Sq., 20-031 Lublin, Poland, Tel.: +48 81 537 6220, Fax: +48 537 619Department of Nuclear Methods, Institute of Physics, M. Curie-Skłodowska University, 1 M. Curie-Skłodowskiej Sq., 20-031 Lublin, Poland, Tel.: +48 81 537 6220, Fax: +48 537 619Faculty of Chemistry, M. Curie-Skłodowska University, 3 M. Curie-Skłodowskiej Sq., 20-031 Lublin, PolandIn this paper, results of positron annihilation lifetime spectroscopy (PALS) studies of MnFe2O4/MCM-41 nanocomposites in N2 and O2 atmosphere have been presented. In particular, the influence of manganese ferrite loading and gas filling on pick-off ortho-positronium (o-Ps) annihilation processes in the investigated samples was a point of interest. Disappearance of the longest-lived o-Ps component with τ5 present in the PAL spectrum of initial MCM-41 mesoporous material in the PAL spectra of MnFe2O4-impregnated MCM-41 measured in vacuum is a result of either a strong chemical o-Ps quenching or the Ps inhibition effects. The intensity I4 of the medium-lived component initially increases, reaching a maximum value for the sample with minimum manganese ferrite content, and then decreases monotonically. Analogous dependence for the intensity I3 of the shortest-lived component shows a maximum at higher MnFe2O4 content. Filling of open pores present in the studied nanocomposites by N2 or O2 at ambient pressure causes partial reappearance of the τ4 and τ5 components, except a sample with maximum ferrite content. The lifetimes of these components measured in O2 are shortened in comparison to that observed in N2 because of paramagnetic quenching. Anti-inhibition and anti-quenching effects of atmospheric gases observed in the MnFe2O4/MCM-41 samples are a result of neutralization of some surface active centers acting as inhibitors and weakening of pick-off annihilation mechanism, respectively.http://www.degruyter.com/view/j/nuka.2015.60.issue-4/nuka-2015-0141/nuka-2015-0141.xml?format=INTmanganese ferriteMCM-41 silicananocompositeo-Ps quenchingpositronium annihilation |
| spellingShingle | Wiertel Marek Surowiec Zbigniew Budzyński Mieczysław Gac Wojciech Study on the effect of atmospheric gases adsorbed in MnFe2O4/MCM-41 nanocomposite on ortho-positronium annihilation Nukleonika manganese ferrite MCM-41 silica nanocomposite o-Ps quenching positronium annihilation |
| title | Study on the effect of atmospheric gases adsorbed in MnFe2O4/MCM-41 nanocomposite on ortho-positronium annihilation |
| title_full | Study on the effect of atmospheric gases adsorbed in MnFe2O4/MCM-41 nanocomposite on ortho-positronium annihilation |
| title_fullStr | Study on the effect of atmospheric gases adsorbed in MnFe2O4/MCM-41 nanocomposite on ortho-positronium annihilation |
| title_full_unstemmed | Study on the effect of atmospheric gases adsorbed in MnFe2O4/MCM-41 nanocomposite on ortho-positronium annihilation |
| title_short | Study on the effect of atmospheric gases adsorbed in MnFe2O4/MCM-41 nanocomposite on ortho-positronium annihilation |
| title_sort | study on the effect of atmospheric gases adsorbed in mnfe2o4 mcm 41 nanocomposite on ortho positronium annihilation |
| topic | manganese ferrite MCM-41 silica nanocomposite o-Ps quenching positronium annihilation |
| url | http://www.degruyter.com/view/j/nuka.2015.60.issue-4/nuka-2015-0141/nuka-2015-0141.xml?format=INT |
| work_keys_str_mv | AT wiertelmarek studyontheeffectofatmosphericgasesadsorbedinmnfe2o4mcm41nanocompositeonorthopositroniumannihilation AT surowieczbigniew studyontheeffectofatmosphericgasesadsorbedinmnfe2o4mcm41nanocompositeonorthopositroniumannihilation AT budzynskimieczysław studyontheeffectofatmosphericgasesadsorbedinmnfe2o4mcm41nanocompositeonorthopositroniumannihilation AT gacwojciech studyontheeffectofatmosphericgasesadsorbedinmnfe2o4mcm41nanocompositeonorthopositroniumannihilation |