Increase of the mean inner Coulomb potential in Au clusters induced by surface tension and its implication for electron scattering

TL;DR

This study uses electron holography to measure how the mean inner Coulomb potential in gold clusters increases as their size decreases, revealing the influence of surface tension and strain effects.

Contribution

It demonstrates that surface tension induces a size-dependent increase in the MIP of gold clusters, which is not explained by bulk properties.

Findings

MIP increases as cluster size decreases

Surface tension causes compressive strain in surface atoms

Small clusters exhibit larger phase shifts than predicted by bulk models

Abstract

Electron holography in a transmission electron microscope was applied to measure the phase shift induced by Au clusters as a function of the cluster size. Large phase shifts Df observed for small Au clusters cannot be described by the well-known equation Df=C_E V_0 t (C_E: interaction constant, V_0: mean inner Coulomb potential (MIP) of bulk gold, t: cluster thickness). The rapid increase of the Au MIP with decreasing cluster size derived from Df, can be explained by the compressive strain of surface atoms in the cluster.