C60 cluster ion bombardment of organic surfaces

This paper reviews the results obtained with a C-60-based ion beam system developed for routine application in ToF-SIMS analysis of organic materials. The bombardment of some representative organic materials by C-60(+) results in yield enhancements of at least 30-100-fold as compared to yields observed under Ga+ bombardment at the same energy. The total ion yields for C-60(+) are in the order of 1-10%. High molecular-weight polymers and monolayer molecular solids are damaged at about the same rate as under Ga+ bombardment. Thick films of molecular solids show similar to100 times less damage than Ga+, such that essentially zero damage sputtering is possible, offering the possibility of analysis well beyond the static limit. The resulting efficiencies are greater than other polyatomic primary ions such as Au-3(+) or SF5+ and >10(3) for Ga+. C-60(+) delivers no more molecular fragmentation than any other primary projectile used in SIMS. Some results on biological test samples to access the potential of the C-60(+) as a primary ion beam in bio-system analysis are reported. A brief discussion on a possible mechanism for ion enhancement by C-60(+) is presented. (C) 2004 Elsevier B.V. All rights reserved.