Dynamic hetero-metallic bondings visualized by sequential atom imaging

The dynamic assembly and disassembly of atoms and molecules is challenging to characterize in real time, with atomic resolution and elemental identification. Here, the authors report direct observation of more than twenty homo and hetero-metallic compounds, including labile Ag-Cu dimers and Au-Ag-Cu trimers. Traditionally, chemistry has been developed to obtain thermodynamically stable and isolable compounds such as molecules and solids by chemical reactions. However, recent developments in computational chemistry have placed increased importance on studying the dynamic assembly and disassembly of atoms and molecules formed in situ. This study directly visualizes the formation and dissociation dynamics of labile dimers and trimers at atomic resolution with elemental identification. The video recordings of many homo- and hetero-metallic dimers are carried out by combining scanning transmission electron microscopy (STEM) with elemental identification based on the Z-contrast principle. Even short-lived molecules with low probability of existence such as AuAg, AgCu, and AuAgCu are directly visualized as a result of identifying moving atoms at low electron doses.

Automated summary

This study directly observes and records the formation and dissociation of unstable dimers and trimers in real time using scanning transmission electron microscopy combined with elemental identification, filling the gaps in previous experiments at atomic resolution.