Ion Beam Sputtering Monitored by Optical Spectroscopy

Optical spectroscopy gives a simple means to follow the evolution of the surface composition during ion beam sputtering. This is illustrated by three examples: air oxidised metals (Al and Cu), various CuAl alloys and the $Cu_{98}Be_2$ alloy. Several time scales are distinguished, corresponding to different processes: the elimination of surface contaminants, the removal of the corroded layer. The implications for the use of ion beam optical spectroscopy in surface analysis are discussed.