Orthopositronium annihilation and emission in mesostructured thin silica and silicalite-1 films

L. Liszkay; M. F. Barthe; C. Corbel; P. Crivelli; P. Desgardin; M. Etienne; T. Ohdaira; P. Perez; R. Suzuki; V. Valtchev; A. Walcarius

doi:10.1016/j.apsusc.2008.05.210

Orthopositronium annihilation and emission in mesostructured thin silica and silicalite-1 films

L. Liszkay, M. F. Barthe, C. Corbel, P. Crivelli, P. Desgardin, M. Etienne, T. Ohdaira, P. Perez, R. Suzuki, V. Valtchev, A. Walcarius

Research output: Contribution to journal › Article › peer-review

Abstract

Mesoporous silica films and MFI-type pure silica zeolite films were investigated using slow positrons. Detection of the 3γ 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 the mesoporous and silicalite-1. A 3γ 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 vacuum is 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.

Original language	English
Pages (from-to)	187-190
Number of pages	4
Journal	Applied Surface Science
Volume	255
Issue number	1
DOIs	https://doi.org/10.1016/j.apsusc.2008.05.210
Publication status	Published - 31 Oct 2008
Externally published	Yes

Keywords

Gamma-ray energy spectroscopy
Mesoporous silica
Monte-Carlo simulation
Positronium
Thermalization
Thin film
Time-of-flight

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10.1016/j.apsusc.2008.05.210

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@article{f078b5cee5f1498894b000c5bb2120f2,

title = "Orthopositronium annihilation and emission in mesostructured thin silica and silicalite-1 films",

abstract = "Mesoporous silica films and MFI-type pure silica zeolite films were investigated using slow positrons. Detection of the 3γ 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 the mesoporous and silicalite-1. A 3γ 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 vacuum is 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.",

keywords = "Gamma-ray energy spectroscopy, Mesoporous silica, Monte-Carlo simulation, Positronium, Thermalization, Thin film, Time-of-flight",

author = "L. Liszkay and Barthe, \{M. F.\} and C. Corbel and P. Crivelli and P. Desgardin and M. Etienne and T. Ohdaira and P. Perez and R. Suzuki and V. Valtchev and A. Walcarius",

year = "2008",

month = oct,

day = "31",

doi = "10.1016/j.apsusc.2008.05.210",

language = "English",

volume = "255",

pages = "187--190",

journal = "Applied Surface Science",

issn = "0169-4332",

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TY - JOUR

T1 - Orthopositronium annihilation and emission in mesostructured thin silica and silicalite-1 films

AU - Liszkay, L.

AU - Barthe, M. F.

AU - Corbel, C.

AU - Crivelli, P.

AU - Desgardin, P.

AU - Etienne, M.

AU - Ohdaira, T.

AU - Perez, P.

AU - Suzuki, R.

AU - Valtchev, V.

AU - Walcarius, A.

PY - 2008/10/31

Y1 - 2008/10/31

N2 - Mesoporous silica films and MFI-type pure silica zeolite films were investigated using slow positrons. Detection of the 3γ 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 the mesoporous and silicalite-1. A 3γ 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 vacuum is 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.

AB - Mesoporous silica films and MFI-type pure silica zeolite films were investigated using slow positrons. Detection of the 3γ 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 the mesoporous and silicalite-1. A 3γ 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 vacuum is 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.

KW - Gamma-ray energy spectroscopy

KW - Mesoporous silica

KW - Monte-Carlo simulation

KW - Positronium

KW - Thermalization

KW - Thin film

KW - Time-of-flight

U2 - 10.1016/j.apsusc.2008.05.210

DO - 10.1016/j.apsusc.2008.05.210

M3 - Article

AN - SCOPUS:53249095798

SN - 0169-4332

VL - 255

SP - 187

EP - 190

JO - Applied Surface Science

JF - Applied Surface Science

IS - 1

ER -

Orthopositronium annihilation and emission in mesostructured thin silica and silicalite-1 films

Abstract

Keywords

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