Positron Beam Characterization of Silica Thin Films with Structurally Ordered Porosity
Well-ordered 2-dimensional (2D) hexagonal and 3-dimensional (3D) cubic mesoporous silicon oxide thin films prepared using triblock Poly(ethylene oxide)-Poly(Propylene oxide)-Poly(ethylene oxide) copolymer species (P123, F127) as the structure-directing agents, are studied by positron beam analysis in parallel with X-ray reflection measurements. It is observed that in the two films with equivalent porosity and pore size (normal to the film surface direction), the shape of mesopores considerably affects positron annihilation behavior. The narrowed positron annihilation Doppler broadening in the 2D hexagonal mesoporous film may suggest a higher positronium formation probability there, owing to a larger effective open volume area originated from the extension of pore channels parallel to the film substrate.
Positron annihilation Positronium Positron beam Porous films
R.S.Yu T.Kurihara X.B.Qin Q.Z.Wang Z.Zhang Y.R.Zhong Z.X.Li B.Y.Wang L.Wei Q.J.Jia
Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China High Energy Accelerator Research Organization (KEK),Tsukuba,Ibaraki 305-0801,Japan Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;Graduate Universit
国际会议
第九届国际正电子与正电子素国际会议(9th International Workshop on Positron and Positronium Chemistry)(PPC–9)
武汉
英文
99-101
2008-05-11（万方平台首次上网日期，不代表论文的发表时间）