Positron Lifetime Spectroscopy on Controlled Pore Glass Porosimetry and Pore Size Distribution
Positron Lifetime Spectroscopy on Controlled Pore Glass Porosimetry and Pore Size Distribution
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DOI：
10.4028/www.scientific.net/msf.607.169
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发表时间：
2008-11
期刊：
影响因子：
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通讯作者：
Stefan Thränert;D. Enke;G. Dlubek;R. Krause-Rehberg
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文献类型：
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作者：
Stefan Thränert;D. Enke;G. Dlubek;R. Krause-Rehberg
利用正电子湮灭寿命光谱（PALS）研究了一系列可控孔玻璃（CPG）。使用常规的lifetime， version 9.0 （LT9）将寿命谱分解为四个分量。最大的寿命τ4在300 K时变化在21 ~ 131 ns之间，这是由于中孔处的正电子湮灭所致。通过氮气吸附和汞侵入技术测定了介孔尺寸（平均自由程）D在1.8 ~ 56 nm之间变化。结果表明，将Tao-Eldrup模型推广到无限长、直径d = d的圆柱体上，可以很好地描述拟合为δ = 0.193 nm的重叠参数δ的实验结果。对光谱进行了分析，得到了o-Ps寿命的分布。提出了一种由τ4分布计算孔径分布n(d)的方法。这种方法特别有趣，因为PALS对传统孔隙度测定法无法精确分析的小孔隙非常敏感。
Positron annihilation lifetime spectroscopy (PALS) is used to study a series of controlled pore glasses (CPG). The lifetime spectra were decomposed into four components using the routine LifeTime, version 9.0 (LT9). The largest lifetime τ4, which is attributed to the annihilation of ortho-positronium (o-Ps) localized at mesopores, varied at 300 K between 21 and 131 ns. The size of mesopores (mean free path), D, was determined by N2 adsorption and Hg intrusion techniques to vary between 1.8 and 56 nm. It is shown that the Tao-Eldrup model extended to cylinders of infinite length and diameter d = D describes well the experiment for an overlap parameter δ fitted to be δ = 0.193 nm. The spectra were also analyzed allowing a distribution of o-Ps lifetimes. A method is developed to calculate the pore size distribution n(d) from the τ4 distribution. This method is of particular interest since PALS is very sensitive to pores being too small to be exactly analyzed by conventional porosimetry.