Programme

I.6 -- Invited, VCTP-46

Date: Tuesday, 5 October 2021

Time: 10:30 - 11:00

A hybrid model for estimation of pore size from ortho-positronium lifetimes in porous materials

L. Anh Tuyen (1), T. Dong Xuan (2), H. A. Tuan Kiet (3), L. Chi Cuong (4), P. Trong Phuc (1), T. Duy Tap (5), Van-Phuc Dinh (2), L. Ly Nguyen (1), N. T. Ngoc Hue (1), P. Thi Hue (1), L. Thai Son (1), D. Van Hoang (1), N. Hoang Long (1), and N. Quang Hung (2)

(1) Center for Nuclear Techniques, Vietnam Atomic Energy Institute, Ho Chi Minh City, Viet Nam; (2) Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City, Viet Nam; (3) Graduate School of Education, University of Pennsylvania, Philadelphia, USA; (4) University of Technical Education, Ho Chi Minh City, Viet Nam; (5) University of Science, Vietnam National University Ho Chi Minh City, Ho Chi Minh City, Viet Nam

We have proposed a novel model for estimating the free-volume size of porous materials based on the analysis of various experimental ortho-positronium (o-Ps) lifetime data. The model is derived based on the semi-classical physics model, which works in the region of large pores (pore size R > 1 nm), combining with the conventional Tao-Eldrup (TE) model, which is applicable only for the small-pore region (R < 1 nm). The proposed model, called the hybrid (HYB) model, is able to smoothly connect the o-Ps lifetimes in the two regions of the pore. In particular, by introducing the o-Ps diffusion probability parameter, the HYB model has reproduced quite well the experimental o-Ps lifetimes in the whole region of pore sizes. It has also described very well the two defined sets of experimental o-Ps lifetimes in the pores with spherical and channel geometries. Hence, the present model is applicable for the pore size in the universal range of 0.2 - 400 nm for most of porous materials with different geometries [1]. Reference: [1] L. Anh Tuyen et al., Radiat. Phys. Chem. 172, 108867 (2020).

Presenter: Nguyễn Quang Hưng