ESD thresholds for KCl

Abstract

Electron stimulated desorption (ESD) energy thresholds for thin KCl layers are measured relative to the target current onset. The applied procedure allow to correct electron beam energy for the contact potential difference in the system. The results show that the energy threshold for ESD of cations and anions (or neutral Cl) coincides with the fundamental absorption edge. The measured threshold energies are about 20 eV for Cl + and about 8 eV for K + and Cl (or Cl -) ESD. The 20 eV threshold for Cl + signal confirms the involvement of an Auger transition in positive halogen ion emission while the 8 eV threshold for the other species is consistent with the so-called "defect-mediated desorption" model of ESD. It is proposed that the near surface lattice instability induced by electronic transition results in a local heating capable of ejecting constituent ion or neutral atom.