The role played by fast electrons in heavy-ion-induced desorption and track formation

Abstract

We have substantial evidence that ion damage tracks and ion-induced desorption are consequences of the electronic excitation that is caused by the incident ion's impact on the target. This is shown by the correlation of the desorption yield/track damage with the energy loss of the ion to electrons during its slowing down process; the extended size of the desorbed molecules and the diameter of the tracks show that the transport of energy away from the ion's path is mediated by these secondary electrons. Experimental studies show that the distribution of damage along an ion track is not uniform, which suggests that statistical fluctuations in the electronic energy loss are involved. These fluctuations can arise from the number of local ionization events produced, the localization of secondary electrons (multi-hit processes), and the Auger decay of inner shell vacancies created. This paper uses the data available to assess the relative importance of these processes and to suggest the sort of experimental data that would improve our understanding of desorption/track-damage phenomena.

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