Emission of secondary particles from metals and insulators at impact of slow highly charged ions

Emission of secondary electrons and ions from clean Au, CxHy-Au, and SiO2 surfaces at impact of slow (v∼0.3 vBohr) ions were measured as function of incident ion charge for 1+≤q≤75+. Electron yields from thermal SiO2 films (150 mm on Si) were found to be lower than those from the other two for q>3+. Yields of negative secondary ions from SiO2 and CxHy-Au were recorded in parallel with electron emission data and exhibit a q4 dependency on incident ion charge. Direct comparison of collisional and electronic contributions to secondary ion production from SiO2 films using a beam of charge state equilibrated Xe (at 2.75 keV/u) shows positive and negative secondary ion yield increases with incident ion charge of >400. Results are discussed in relation to key signatures of electronic sputtering by Coulomb explosions