Structure and Charge Heterogeneity in Isomeric Au25(MBA)18 Nanoclusters - Insights from Ion Mobility and Mass Spectrometry.

Atomically precise Au25(MBA)18 nanoclusters were investigated by mass spectrometry and ion mobility spectrometry. We show that clusters sharing the same chemical composition and bearing the same net charge may display different structures and different charge repartition patterns. Namely, the number of charges corresponding to de-protonation of the ligand carboxyl groups is not the same for all detected species. Part of the observed heterogeneity is a consequence of spontaneous electron loss occurring in the gas phase, which modifies the net charge of the clusters, while maintaining the initial protonation state.