Relaxation processes in solid methane pre-irradiated with an electron beam

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Vol. 433; pp. 23 - 27
• Main Authors: Savchenko, E.V., Kirichek, O., Lawson, C.R., Khyzhniy, I.V., Uyutnov, S.A., Bludov, M.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2018
• Subjects: Activation spectroscopy; Charged species; Electron irradiation; Recombination; Relaxation; Solid methane; Activation spectroscopy; Relaxation; Recombination; Charged species; Electron irradiation; Solid methane
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/j.nimb.2018.06.031

•Radiation effects were studied by thermally stimulated activation spectroscopy.•Two peaks of relaxation emissions of electrons and particles indicate two stages of the relaxation.•Accumulation of negative charge in pre-irradiated methane films was first detected. The relaxation processes in CH4 solids irradiated by an electron beam were studied with a focus on post-irradiation phenomena. Because of absence of thermally stimulated luminescence (TSL) from pure solid methane we applied current activation spectroscopy method – thermally stimulated exoelectron emission (TSEE). Two broad features were detected near 18 and 43 K. Their relative intensity appeared to depend on irradiation time. The experiments performed with a variable voltage applied to an electrode for current detection first revealed significant accumulation of uncompensated negative charge in pre-irradiated methane films. The TSEE current was detected at negative voltages up to −35 V. Concurrently with thermally stimulated yield of electrons the total yield of thermally stimulated post-desorption (TSpD) from pre-irradiated solid methane film was detected. Correlation of TSEE and TSpD yields is discussed and compared with the temperature behavior of solid methane subjected to a neutron flux.