Again, quantitative desorption analysis was done for the first 6 TPD where multiple experiments were available. The total number of C2D4 molecules adsorbed per Pt4Ge cluster in the 2 nd TPD was ~1.71, of which ~86% desorbed intact, with the balance decomposing to liberate D2 and deposit ~0.5 C/cluster on average (Table ). Given that C atoms deposit in pairs, we interpret this to mean that the Pt4Ge clusters initially had one or two C2D4 molecules adsorbed, and that on ~25% of the clusters, one ethylene decomposed to deposit two C atoms.