Study of highly ordered mesoporous silica films by positronium time-of-flight spectroscopy
Positronium time-of-flight (Ps-TOF) measurement can be used to obtain the energy of triplet ortho-positronium (o-Ps) emerging from solid surfaces, by which the open porosity and pore interconnectivity can be deduced. Different surfactants such as cetyltrimethylammonium bromide (CTAB), triblock copolymer EO106PO70EO106 (F127) and EO20PO70Eo20 (P123) were used to fabricate porous films with different pore shapes (two dimensional hexagonal, three dimensional hexagonal and three dimensional cubic) by evaporation-induced self-assembly (EISA) method. The emission of o-Ps from porous films was examined as a function of the incident positron energy (Ein). It was found that when CTAB:Si=0.2, which is the best molecular ratio for the formation of highly ordered pores, the most obvious Ps peak is obtained. But for the samples with two dimensional pores, a broader peak appeared which is mainly induced by the long channel of the open pores.
X.B.Qin R.S.Yu X.Z.Cao B.Y.Wang L.Wei T.Kurihara
Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China；Graduate School of Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China；High Energy Accele High Energy Accelerator Research Organization (KEK),1-1 Oho,Tsukuba,Ibaraki,305-0801,Japan
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
102
2008-05-11（万方平台首次上网日期，不代表论文的发表时间）