ESCA STUDIES OF A BRASS SURFACE SUBJECTED TO GAS-JET-ENHANCED SPUTTERING IN A GLOW-DISCHARGE

Electron spectroscopy for chemical analysis (ESCA) is used to study se lected regions of a brass surface subjected to gas-jet-enhanced sputte ring in a glow discharge. Gas jets directed at the sample surface duri ng sputtering in a glow discharge increase the removal rate of sample material from the surface and cause changes to the surface which are v isually evident in the formation of craters and surface deposits. Chan ges in chemical composition of these regions are observed when success ive atomic layers are removed fron the sample by the ion beam etching accessory in the ESCA spectrometer. The effects of ion bombardment can be explained in terms of the selective sputtering of one bulk compone nt over another. The surfaces in the sputtered craters were found to b e depleted of the higher-sputtering-yield component, Zn, when compared to the bulk composition. In a deposit, the component with the highest sputtering yield was found to be more concentrated in layers closest to the bulk material. The component with the lowest sputtering yield w as found at relatively higher concentrations nearest the deposit surfa ce. The component with the higher sputtering yield is selectively sput tered first during the glow discharge, and consequently is deposited w ith a higher concentration closest to the bulk, the converse being tru e for the lowest-sputtering-yield component.