Orthopositronium annihilation and emission in mesostructured thin silica and silicalite-1 films
Ecole Polytechnigue
Author(s): Liszkay L (Liszkay, L.)1, Barthe MF (Barthe, M. -F.)2, Corbel C (Corbel, C.)3, Crivelli P (Crivelli, P.)1,7, Desgardin P (Desgardin, P.)2,
Etienne M (Etienne, M.)4, Ohdaira T (Ohdaira, T.)5, Perez P (Perez, P.)1, Suzuki R (Suzuki, R.)5, Valtchev V (Valtchev, V.)6, Walcarius A (Walcarius,
A.)4
Source: APPLIED SURFACE SCIENCE
Times Cited: 0
References: 13
Volume: 255
Issue: 1
Pages: 187-190
Published: OCT 31 2008
Citation Map
Conference Information: 11th Workshop on Slow Position Beam Techniques for Solids and Surfaces
Musee Sci Naturelles, Orleans, FRANCE, JUL 09-13, 2007
Ville Orleans; Conseil Reg Loiret; Reg Ctr; Ctr Natl Rech Sci; Commiss Energ Atom
Abstract: Mesoporous silica films and MFI-type pure silica zeolite films were investigated using slow positrons. Detection of the 3 gamma
annihilation fraction was used as a quick test to estimate the emission of orthopositronium (o-Ps) into vacuum. Positronium time-of-flight (TOF)
spectroscopy, combined with Monte-Carlo simulation of the detection system was used to determine the energy of o-Ps emitted from the films.
Evidence for an efficient o-Ps emission was found in both themesoporous and silicalite-1. A 3 gamma fraction in the range of 31-36 % was found in
the films with the highest o-Ps yield in each type of porous material, indicating that 40-50 % of the implanted positrons form positronium in the pore
systems with very different pore sizes. Time-of-flight measurements showed that the energy of the orthopositronium emitted into vacuumis below
100 meV in the film with 2-3 nm pores at 3 keV positron energy, indicating an efficient slowing down but no complete thermalization in the porous
films of 300-400 nm thickness. (C) 2008 Elsevier B.V. All rights reserved.
Document Type: Proceedings Paper
Language: English
Author Keywords: positronium; Monte-Carlo simulation; gamma-ray energy spectroscopy; time-of-flight; mesoporous silica; thin film;
thermalization
KeyWords Plus: POSITRON-ANNIHILATION; POROSITY
Reprint Address: Liszkay, L (reprint author), CEA, IRFU, F-91191 Gif Sur Yvette, France
Addresses:
1. CEA, IRFU, F-91191 Gif Sur Yvette, France
2. CNRS, CEMHTI, F-45071 Orleans, France
3. CEA, IRAMIS, Solides Irradies Lab, F-91128 Palaiseau, France
4. Nancy Univ, CNRS, Lab Chim Phys & Microbiol Environnement, UMR7564, F-54600 Villers Les Nancy, France
5. Inst Adv Ind Sci & Technol, Tsukuba, Ibaraki 3058568 Japan
6. Univ Haute Alsace, ENSCMu, CNRS, Lab Mat Porosite Controlle,UMR 7016, F-68093 Mulhouse, France
7. ETH, Inst Teilchenphys, CH-8093 Zurich, Switzerland
E-mail Addresses: Laszlo.Liszkay@rmki.kfki.hu
Publisher: ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
IDS Number: 355RV
ISSN: 0169-4332
DOI: 10.1016/j.apsusc.2008.05.210