Effect of projectile parameters on charge state formation of sputtered atoms

Abstract

In the majority of the electron-exchange models, it is assumed that the charge state formation processes of atoms sputtered (scattered) from a solid do not depend on projectile parameters. This means that an electronic subsystem excitation produced by projectiles in the impact region does not affect on the ionization probability (formula presented) of ejected atoms. In the present work this basic assumption has been subjected to experimental examination. To study it the clean surface of a silicon sample was bombarded by the following atomic and molecular projectiles: (formula presented) ions with the energy of (formula presented) and 18 keV; (formula presented) ions with (formula presented) (formula presented) ions with (formula presented) and 9 keV/atom. The kinetic energy distribution (formula presented) of sputtered (formula presented) ions were used to obtain information on (formula presented) It was found that the ionization probability (formula presented) depends on the projectile parameters increasing with the rise of energy (formula presented) mass (formula presented) and the number m of atoms in projectile. The results obtained are discussed in the framework of the simple model in which the charge state formation occurs in the electron exchange between the sputtered atom and a local surface area where the relaxation of the electronic subsystem excited by the projectile impact takes place. © 2002 The American Physical Society.