In the technique of analysis known as secondary ion mass spectrometry (SIMS), a beam of energetic ions (2-40 keV) strikes a sample(pd dislodges atoms lying near the surface by the process known as sputtering, Figure 1. A small fraction (104 - 10 2) of the sputtered sample atoms is emitted in a charged state, the so-called secondary ions. Because of their electrical charge, the secondary ions can be attracted by appropriate electrical fields into a mass spectrometer which disperses the ions according to their mass-to-charge ratio. Ion detection is accomplished by either an electrical detector or a photographic plate. By varying the strength of the magnetic and/or electrical field of the mass spectrometer, a mass spectrum of the positive or negative sputtered ions in the form of intensity versus mass-to-charge ratio is obtained.