Matrix-enhanced cluster-SIMS

We have used 23 keV C-60(+) projectiles in the event-by-event bombardment and detection mode to investigate the emission of the gramicidin S [M-H](-) ion embedded in a matrix of sinapic acid. We have observed an increase in the gramicidin S [M - H]- ion of approximately eight times by controlling the ratio of gramicidin S to sinapic acid. The maximum of the gramicidin S [M - H]- yield occurs at a matrix/analyte ratio of 10:1. This ratio is different from those typically used in matrix-assisted laser desorption/ionization. (c) 2006 Elsevier B.V. All rights reserved.