Influence of primary ion species on the secondary cluster ion emission process from SAMs of hexadecanethiol on gold

In contrast to the well-known increase in secondary ion yield for molecular secondary ions when moving from lighter to heavier (e.g. Ar+ to Xe+) or from monoatomic to polyatomic (e.g. Xe+ to SF5+) primary ions, we find a distinctly different behaviour for the secondary cluster ions. For polyatomic primary ions, there is a decrease in secondary ion yield for the gold-hexadecanethiolate clusters whereas the relative decrease of the secondary ion yield ξY with increasing y remains almost constant for all investigated primary ions.