The yield of CN from glycine rises from one CN per projectile impact to two when the sample is covered with a nominally 1 nm thick layer of silver. These yields were obtained for bombardment with Au-400(4+) projectile with 136 keV impact energy. A multitude of CN-based clusters, e.g. AgxOy(CN)(z) are produced concurrently. As a result, a total of three CN-based secondary ions are generated per projectile impact. The exceptionally high yield for CN is of interest for biological SIMS. (c) 2006 Elsevier B.V. All rights reserved.