FLUENCE DEPENDENT ELECTRON-EMISSION AS A MEASURE OF SURFACE MODIFICATION INDUCED BY SWIFT HEAVY-IONS

From the fluence dependence of low energy electron yields induced by s wift heavy ions, one can deduce a cross section for surface transforma tion by electronic processes. For a clean metal surface exposed to a c ontaminant gas in ultrahigh vacuum, this cross section is related to t he electronic desorption. In general, this cross section is also relat ed to structural modification of the surface, The dependence of electr on yields, surface transformation cross section and secondary ion yiel ds for carbon foils show a different dependence on the electronic stop ping power which is a hint for different ejection mechanisms involved.