Radiation effects in nitrogen and methane “ices”

Abstract

Abstract The radiation effects and relaxation processes in N2 and CH4 solids irradiated by an electron beam were studied with a focus on post-irradiation phenomena. The study was performed using optical and current spectroscopy methods: cathodoluminescence (CL) and developed by our group nonstationary luminescence (NSL) as well as nonstationary desorption (NSD) methods, together with activation spectroscopy techniques – spectrally resolved thermally stimulated luminescence (TSL), and thermally and photostimulated exoelectron emission (TSEE/PSEE). An afteremission of electrons was observed from N2 and CH4 solids pointing to an electrostatic charging of both films. The PSEE and TSEE from methane films were detected for the first time demonstrating important role of charge centers in radiation effects. Formation of negatively charged ions in methane by electron attachment was verified via PSEE followed by TSEE. Possible scenarios of N4+ and N3+ neutralization via dissociative recombination are discussed and data indicating space distribution of these centers are presented.