Positronium annihilation and pore surface chemistry in mesoporous silica films

Lifetimes of ortho-positronium in mesoporous silica films were measured before and after surface trimethylsilylation of -OH groups. Variations of positronium lifetimes in the mesopores upon the surface modification indicate that the interaction between positronium and the pore surface is weakened in...

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Bibliographic Details
Published in:Applied physics letters 2007-07, Vol.91 (2), p.024102-024102-3
Main Authors: He, Chunqing, Oka, Toshitaka, Kobayashi, Yoshinori, Oshima, Nagayasu, Ohdaira, Toshiyuki, Kinomura, Atsushi, Suzuki, Ryoichi
Format: Article
Language:English
Subjects:
ANNIHILATION
LIFETIME
PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
POSITRONIUM
POSITRONS
SILICA
SLOWING-DOWN
THIN FILMS
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Summary:Lifetimes of ortho-positronium in mesoporous silica films were measured before and after surface trimethylsilylation of -OH groups. Variations of positronium lifetimes in the mesopores upon the surface modification indicate that the interaction between positronium and the pore surface is weakened in the pores, whose surface is covered with - C H 3 groups, in comparison with those covered with -OH groups. This is consistent with the authors' previous observation that positronium slowing down is less efficient in the pores covered with - C H 3 groups. The present work demonstrates that in the porosimetric application of positron annihilation lifetime spectroscopy, the interaction between positronium and the pore surface has to be properly taken into consideration.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.2756310