MECHANISM OF ION FORMATION AND ION EMISSION DURING SPUTTERING

It is demonstrated that the degree of ionization of secondary particles emitted from a solid surface under ion bombardment cannot be predicted by the Saha-Langmuir equation. For an understanding of the ion emission it is necessary to separate the process of ion formation and the following emission. There exists a great number of different processes resulting in the formation of an ion on the surface. These processes can be disentangled by means of a systematical mass spectrometrical analysis. The probability for an ion to leave the surface without neutralization depends on various parameters as ionization potential and velocity of the emitted particle, work function and temperature of the surface etc. © 1969 Springer-Verlag.