Secondary Ion Mass Spectrometry (SIMS) is based on the sputtering of solid sample surfaces by primary ion bombardment. Primary ions impinging on the sample surface trigger a cascade of atomic collisions. A portion of the single atoms and clusters ejected are spontaneously ionized. These secondary ions are characteristic of the composition of the analyzed area. They are separated according to their mass/charge ratio. Elemental mapping or depth profiles containing quantitative information can be obtained for a selected mass.