Substrate effects on the analysis of biomolecular layers using Au+, Au3+ and C60+ bombardments

Effects of platinum silicon, graphite and PET substrates on the secondary ion yield of sub-monolayer and multilayer samples of Cyclosporin A following 20 keV Au+, Au3+and C60+ impacts have been investigated. The obtained results of sub-monolayer samples show that platinum enhances the yield of the pseudo-molecular ion following Au+ and Au3+ impacts due to the high density of the substrate that enables the energy of the primary ions to be deposited near the surface. C60+ impacts on sub-monolayer samples are less effective, but there is an enhancement on PET substrates. Impacts of 20 keV Au+ and Au3+ are not very efficient on multilayer samples. 20 keV C60+ impacts enhance the yields significantly, especially for the relatively high molecular weight [M+H]+ ion.