Positrons and positronium in macromolecules: Consequences of different charge states. (January 2023)

• Record Type: Journal Article
• Authors: Kobayashi, Yoshinori; Sato, Kiminori; Yamawaki, Masato; Michishio, Koji; Oka, Toshitaka; Washio, Masakazu
• Is Part Of: Radiation physics and chemistry. Volume 202(2023)
• Publication Date: 2023-01
• Subjects: Positron -- Positronium -- Macromolecule -- Polar group -- Free volume -- Trapping; Radiation chemistry -- Periodicals; Radiometry -- Periodicals; Radiation -- Periodicals; Chimie sous rayonnement -- Périodiques; 539.2
• DOI: 10.1016/j.radphyschem.2022.110590
• Languages: English
• ISSNs: 0969-806X

Abstract

Abstract: Because of their different charge states, positrons and positronium (Ps) behave quite differently in macromolecules. The behavior of positively charged positrons is strongly influenced by electrostatic interactions. In nonpolar macromolecules such as polyethylene, energetic positrons, if not incorporated into Ps, fall into a delocalized state. These positrons are sensitively trapped by polar groups, if any. On the other hand, charge-neutral Ps is localized in a free volume regardless of the macromolecule's chemical structure. In this study, we discuss the behavior and annihilation characteristics of positrons and Ps in various macromolecules, emphasizing their differences. Highlights: Positrons fall into a delocalized mobile state in nonpolar macromolecules. Positively charged positrons are sensitively trapped by polar groups. Charge-neutral positronium is trapped by free volume. Chemical structure has different effects for positron and positronium.