Massive clusters: Secondary emission from qkeV to qMeV. New emission processes? New SIMS probe?

We report on the secondary ion emission under massive cluster (from 100 to 1600 atoms) impacts from different organic samples. The study has been preformed at the Orsay Tandem Accelerator equipped with a Liquid Metal Ion Source (LMIS) using a time of flight (ToF) mass spectrometer (MS) with a multianode localization detector. The influence of the projectile mass and energy is studied in order to investigate the new hydrodynamic regime of the solid-particle interaction related to the use of these massive clusters. We shall present this study, the energy range of which extends from 10 qkeV up to 4 qMeV. The results show that the ionic emission intensities increase with the energy and the mass of the projectiles (from n/q = 25 to n/q = 400) which allows the simultaneous emission of a few tens ions of the same mass per impact, what had never before been observed in SIMS. The study of the positive ionic emission is surprising. There is an important emission (also a few tens ions) of H+, H-2(+), H-3(+) and C+. The setup permits to determine the angular velocity distributions of the ejected ions. We present the results which permit to distinguish four classes of ionic emission. The molecular ions and molecular clusters are preferentially pushed from the surface by a pressure wave which rises perpendicularly to the beam trajectory. Copyright (C) 2010 John Wiley & Sons, Ltd.