TOF-SIMS Analysis Using Ceo- Effect of Impact Energy on Yield and Damage

摘要

C_(60)has been shown to give increased sputter yields and,hence,secondary ions when used as a primary particle in SIMS analysis.In addition,for many samples,there is also a reduction in damage accumulation following continued bombardment with the ion beam.In this paper,we report a study of the impact energy (up to 120 keV)of C_(60)on the secondary ion yield from a number of samples with consideration of any variation in yield response over mass ranges up to m/z 2000.Although increased impact energy is expected to produce a corresponding increase in sputter yield/rate,it is important to investigate any increase in sample damage with increasing energy and,hence,efficiency of the ion beams.On our test samples including a metal,along with organic samples,there is a general increase in secondary ion yield of high-mass species with increasing impact energy.A corresponding reduction in the formation of low-mass fragments is also observed.Depth profiling of organic samples demonstrates that when using C_(60),there does not appear to be any increase in damage evident in the mass spectra as the impact energy is increased.