Charging effects in gold nanoclusters grown on octanedithiol layers

Abstract

Strong interaction of gold with the terminal sulfur atoms of dithiol molecules on Au(111) effectively suppresses the penetration of deposited Au atoms through the dithiol layer and results in the formation of homogeneous Au nanoclusters. These nanoclusters, 10–15 Å (σ<2 Å) in height, spread over the surface with a density of ∼1.2×1013/cm2 for coverage between 0.25–2.5 monolayers. Decoupling of the clusters from Au(111) by the octanedithiol layer (∼12 Å in thickness) and the small self-capacitance of these nanoparticles (10−19–10−18 F) make it possible to observe both the Coulomb blockade in scanning tunneling spectroscopy and the Au 4f core level shifts in x-ray photoelectron spectroscopy at room temperature. Both phenomena can be attributed to a common physical origin—e2/2C—the Coulomb energy of charged particles.