Ionization Probabilities of Polycrystalline Metal Surfaces

Abstract

Quantification of secondary ion (SI) yields presupposes knowledge of a large variety of apparative and sample specific parameters. Although, at least for metals, the main portion of in vacuum sputtered material is in neutral form, still enough ions are emitted to establish qualitative analysis of most metallic components. When oxygen or oxygen containing gases are admitted, SI yields of the most metals increase by orders of magnitude, thus enabling material analysis down to monolayer range. This “oxygen effect” is often ascribed to the high electronegativity of oxygen, which may be the cause of a local polarisation of the metal bond at the surface, favouring heterolytic detachment.