Influence of massive projectile size and energy on secondary ion yields from organic surfaces

We investigated the influence of the projectile size and energy using Aunq+ clusters (5 < n < 400, 1 < q < 4) impacting on a glycine target with a 19q-34q keV energy range. We show that both CN− fragment and Gly− molecular ion yields are equivalent for projectiles with n > 9 and increase with the energy per projectile atoms. A maximum yield of 0.5 (50%) for both CN− and Gly− was obtained with the Au4004+ projectile at 136 keV total energy. For Gly−, the yield enhancement is linear for Aun when n > 5. Trends for the CN− fragment are different. A nonlinear yield enhancement proportional to n3 is observed for Aun when n < 9.