Bombardment of Alkali and Alkali-Earth Halides by Ions and Electrons

摘要: For alkali and earth halides ion as well electron bombardment are efficient processes leading to continuous surface erosion [1,2]. While sputtering of metals under is understood in terms a collision cascade emission mechanism [3], for no such process can account any particle due the negligible momentum transfer. Electronic have been proposed explain or photon induced desorption [4,5]. The key steps generation an exciton, which trapped at halogen site. Then lattice raised excited state, thermally relaxes form molecular-like state with neighbouring ion. In this new system make non-radiative transition ground energy then released ions kinetic directed along crystal direction. Thus replacement sequence line takes place, if reaches surface, atom caused. Therefore expelled atoms feature directional hyperthermal energies [6]. diffusion defects lead alkali-earth enrichment on surface. These excess metal prevent further or, vapour pressure high enough may evaporate random directions