EXIT CONDITIONS FOR SECONDARY-ION EMISSION INDUCED BY KEV CLUSTER BOMBARDMENT

The emission of secondary ions from CsI and phenylalanine surfaces via keV atomic and cluster projectile impacts was studied with coincidenc e counting time-of-flight mass spectrometry. The results show that not all desorption events from a given projectile are equivalent. The deg ree of secondary ion correlation was observed to be an inverse functio n of the kinetic energy and complexity, or efficiency, of the primary ion. For the cases studied, changes in secondary ion correlation are a ttributed to a change in the ion formation pathway as well as the surf ace volume excited by a primary projectile.