Positron annihilation in hypercrosslinked polystyrenes |
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| Affiliation: | 1. Radiation Science Center, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan;2. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4 Kosygin str., Moscow 117334, Russia;3. RCNT, University of Tokyo, JAERI, Tokai-Mura, Ibaraki 319-1106, Japan;1. Guangxi Key Laboratory of Electrochemical and Magnetochemical Function Materials, College of Chemistry and Bioengineering, Guilin University of Technology, Guilin 541004, China;2. State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China;1. Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, China;2. School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China;1. Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, (CSIR-CDRI), BS-10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India;2. Endocrinology Division, CSIR-Central Drug Research Institute, (CSIR-CDRI), BS-10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India;1. Advanced Medical Research Center, Hyogo University of Health Science, 1-3-6 Minatojima, Kobe 650-8530, Japan;2. KOBE Chemical Genetics., Inc., 2-2-2 Minatojima-nakamachi, Chuo-ku, Kobe 650-8530, Japan;3. Discovery Research Department, Chugai Pharmaceutical Co., Ltd, 200 Kajiwara, Kamakura 247-8530, Kanagawa, Japan |
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| Abstract: | Positron annihilation in hypercrosslinked polystyrene, called CPS(0.3)150E, has been studied as a function of temperature in the range from 35 to 370 K. The positron lifetime spectra were resolved into five components using the PATFIT and MELT programs. The annihilation rate constant of the longest-lived component was found to increase linearly with increasing temperature. Remarkably, the distribution of o-Ps lifetimes resolved by MELT was shown to broaden with decreasing temperature. Moreover, an effect of the oxygen pressure on the positronium characteristics was also investigated in another hypercrosslinked polystyrene, CPS(0.3)100E. The oxygen pressure varied from vacuum to 6 atm. The annihilation rate constants of the long-lived components were observed to increase linearly as a function of the oxygen pressure, which demonstrates a dependence of the kinetic of o-Ps quenching on the pore size. |
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