Size dependent lattice constant change of thiol self-assembled monolayer modified Au nanoclusters studied by grazing incidence x-ray diffraction

• Gold nanoclusters were electrochemically aggregated.
• Cluster size and interatomic distance, i.e., lattice constant, were obtained by GIXRD measurement.
• Cluster size dependent lattice constant change was systematically investigated.

Size and lattice constant of thiol self-assembled monolayer (SAM)-modified gold nanoclusters (GNCs) assembled on Au(111) surfaces after each electrochemical treatment were investigated using grazing incidence x-ray diffraction (GIXRD). When the potential was swept between 0 and 1.3 V (vs. Ag/AgCl), the size and lattice constant of GNCs slightly decreased due to the oxidative desorption of the SAMs. As the number of potential cycles increased, the size of GNCs started to increase due to the aggregation, while the lattice constant continued to decrease due to further desorption of the SAMs from the GNCs. After most of the SAMs were removed from the GNCs, the size and lattice constant monotonically increased with the number of potential cycles. The size dependent lattice constant change was observed when GNCs were smaller than ~ 35 Å.

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