Positron annihilation in latex templated macroporous silica films: pore size and ortho-positronium escape - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue New Journal of Physics Année : 2012

Positron annihilation in latex templated macroporous silica films: pore size and ortho-positronium escape

Résumé

Depth profling of positron annihilation characteristics has been used to investigate the pore size distribution in macroporous PMMA latex templated SiO2 films deposited on glass or Si and prepared with 11-70% porosity. The correlation between the annihilation characteristics shows that o-Ps escape (re-emission) into vacuum occurs in all films with a porosity threshold that is pore size dependent. For 60 ± 2% porosity, the o-Ps reemission yield decreases from ~ 0:25 to ~ 0:11 as the pore size increases from 32 to 75 nm. The o-Ps reemission yield is shown to vary linearly with the specific surface area per mass unit and the slope is independent of pore size, 9:1±0:4 g cm-1. For 32 nm pores, the o-Ps annihilation lifetimes in the films, 17(2)ns and 106(5) ns, show that o-Ps annihilates from micropores with small effective size (1:4 ± 4 nm) and from macropores with large effective size (~ 32 nm). Above the porosity threshold, the o-Ps-escape model predicts the annihilation lifetime in the films to be 19±2 ns. Our results imply that o-Ps effciently detects the microporosity present in the silica walls. At low porosity, its capture into the micropores competes with its capture into the macropores. At higher porosity (when the distance between micropores and macropores become small), this capture into the micropores assists the capture into the macropores.
Fichier principal
Vignette du fichier
NJP_11_v3_accepted.pdf (584.28 Ko) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

hal-00695634 , version 1 (09-05-2012)

Identifiants

Citer

L. Liszkay, F. Guillemot, C. Corbel, J.P. Boilot, T. Gacoin, et al.. Positron annihilation in latex templated macroporous silica films: pore size and ortho-positronium escape. New Journal of Physics, 2012, 14, pp.065009. ⟨10.1088/1367-2630/14/6/065009⟩. ⟨hal-00695634⟩
277 Consultations
164 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More