Effects induced by electron beam in methane ices

Self-oscillations in solid methane irradiated by electrons

“…5). These values are close to the experimental ones [30]], in which the period is of the order of 10 s. Generally speaking, it follows from the calculations that the period depends on many parameters of the sample and irradiation, but for the same parameters of the sample, the period decreases with increasing pumping, as noted in Section 2 and observed in our previous experiments [30]. The period of oscillations decreases with G increasing also for oscillations with a large period determined by the time before the outburst.…”

“…We will present the solutions describing oscillations with a large period and a sharp maximum in the temperature dependence of oscillations on time and oscillations having a short period and located in the vicinity of the maximum oscillations with a long period. This type of dynamics was observed experimentally in [29,30].…”

“…We investigate temperature fluctuations associated with the accumulation of defects. At the electron energies used in the experiments [29,30], of the order of 1 keV, the energy transfer to the hydrogen atom is small (less than the hydrogen binding energy in the molecule) and therefore its direct knocking from the molecule is unlikely. Methane dissociation occurs as a result of subthreshold processes, for example, during energy transfer from excited states, in particular, from the long-lived triplet states [31].…”

“…A key feature of the experiments [29,30] is the fact that the electron range (that is, the region in which defects are created by irradiation) at an electron energy of 1 keV is of the order of 0.1 µm that is much less than the thickness of the sample. In this case, the temperature distribution in the sample will be heterogeneous and the study of selfoscillations is a difficult task.…”

“…In experiments [29,30], when solid methane was irradiated with electrons at helium temperature, explosive delayed desorption of particles was detected. In contrast to the case of ion bombardment [27,28] with high energy during the bursts stimulated by electron beam, the periodic oscillations of the desorption yield were also observed.…”