Static SIMS: ion detection efficiencies in a channel electron multiplier

The energy and spatial counting efficiencies of single channel electron multipliers CEMs.have been analysed for axially incident argon and xenon ions with energies in the range 0.1 to 9 keV. Theoretical predictions have been compared with data for a Philips X919BL CEM. It is recommended that, to minimise the variation in detection efficiencies between ion species, the ions should impact the detector surface at grazing incidence and at as high an energy as possible, typically 10 to 20 keV. Furthermore, the CEM should be operated in the plateau part of the curve of efficiency as a function of detector voltage determined using ions of high mass. Crown Copyright q1999 Published by Elsevier Science B.V. All rights reserved