In ToF-SIMS, each chemical species produces a unique peaks pattern following its specific isotopic distribution. Some elements, such as Rh, exhibit simple distributions with a single peak at 103 m/z. In contrast, elements like Ru and Pd generate broader peaks patterns due to the presence of multiple isotopes. When analyzing a sample containing Ru, Pd, and Rh, the resulting peaks pattern, known as the composite mass spectrum, is a combination of the individual isotopic distributions of these three elements as illustrated in Figure .