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On the peculiarities of positron annihilation features in silicalite-1 and Y-zeolites |
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| Authors: | Zs Kajcsos G Dupltre L Liszkay I Billard A Bonnenfant E Azenha K Lzr G Pl-Borbly P Caullet J Patarin L Lohonyai |
| Institution: | a KFKI Research Institute for Part. Nucl. Physics, P.O.B. 49, H-1525 Budapest 114, Hungary b Laboratoire Chimie Nucléaire, IReS, IN2P3/CNRS, BP 28, 67037 Strasbourg Cedex 2, France c Institute of Isotope and Surface Chemistry, P.O.B. 77, H-1525 Budapest, Hungary d Central Research Institute for Chemistry, P.O.B. 19, H-1525 Budapest, Hungary e Laboratoire Materiaux Minéraux, URA CNRS 428 3, rue A. Werner, 68093 Mulhouse Cedex, France |
| Abstract: | Conditions that facilitate high Ps formation and interactions that modify the o-Ps lifetime were investigated by positron annihilation techniques in silicalite-1 and various Y-zeolites. Long lifetimes, up to 135 ns, and o-Ps fractions as high as 40% were found. The influence of heat treatment (in the range of 90–520 K), capillary condensation of N2 (0.085 MPa) and correlation with water removal was examined in Y-zeolites and in silicalite-1, respectively. The latter matrix was also studied in the presence of liquids. In various samples unexpected features were found (peculiar changes in the 2γ/3γ ratio, inversion in the trend of lifetime variations, disappearance of specific components, etc.), denoting the complexity of the processes governing the fate of e+ and Ps. |
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