文献类型：期刊文献

英文题名：Effects of the π-electrons in fused polycyclic aromatic hydrocarbons on positron annihilation

作者：Du, Yijun[1]; Zhao, Junhu[1]; Wang, Chen[1]; Qi, Chenze[1]; Li, Yan[1]; Tao, Hongyu[1]; Zhang, Peng[2]; Cao, Xingzhong[2]; Wang, Baoyi[2]

机构：[1] Zhejiang Key Liaboratory of Alternative Technologies for Fine Chemicals Process, Shaoxing University, Shaoxing, 312000, China; [2] Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China

年份：2019

卷号：163

起止页码：39

外文期刊名：Radiation Physics and Chemistry

收录：EI(收录号：20192307004202)、Scopus(收录号：2-s2.0-85066449522)

基金：We acknowledge the financial support from the National Natural Science Foundation of China (Grant Nos. 11575117, 11705117, 31800292 ), and the Zhejiang Provincial Natural Science Foundation of China (Grant No. LQ16C050001 ).

语种：英文

外文关键词：Carbon - Doping (additives) - Electrons - Formaldehyde - Ionization - Ionization potential - Mineral oils - Phenolic resins - Phenols - Polycyclic aromatic hydrocarbons - Positron annihilation - Positrons

外文摘要：The mesoporous phenol-formaldehyde resins (PFR) were synthesized using formaldehyde, phenol, F127 template as raw materials by high temperature hydrothermal method under different temperatures. Nitrogen doped mesoporous PFR were synthesized in the same way with another additional raw material HMTA. Two series of carbon materials PCs and PCNs were obtained after calcinating PFR at 700, 800, 900 °C. N2 adsorption analysis indicates that both the two kind of carbon materials have relatively large specific surface area (325–619 cm2/g for PCs and 431–580 cm2/g for PCNs). TEM and XRD analyses prove highly ordered mesoporous structure of the samples. Both the elemental analysis and IR results suggest a high carbon content and the abundant fused-ring structure of the test materials. The positron annihilation spectra show that the corresponding intensity I3 of the longest lifetime component τ3 is less than 2%, indicating that the π electrons in the fused rings with low ionization energy are capable of trapping positrons and inhibiting the formation of o-Ps. ? 2019 Elsevier Ltd