'Spillout' effect in gold nanoclusters embedded in c-Al2O3(0001) matrix

TL;DR

This study investigates the 'spillout' effect in gold nanoclusters embedded in a crystalline alumina matrix, revealing size-dependent plasmon resonance shifts due to electron density reduction.

Contribution

It demonstrates the size-dependent plasmon resonance shifts in gold nanoclusters embedded in c-Al2O3, highlighting the 'spillout' effect as a key factor.

Findings

Plasmon resonance observed at 561-579 nm for clusters 1.72-2.4 nm in size.

Redshift of plasmon peak with decreasing cluster size.

Size range of clusters exhibiting the 'spillout' effect: 157-427 Au atoms.

Abstract

Gold nanoclusters are grown by 1.8 MeV Au^\sup{2+} implantation on c-Al\sub{2}O\sub{3}(0001)substrate and subsequent air annealing at temperatures 1273K. Post-annealed samples show plasmon resonance in the optical (561-579 nm) region for average cluster sizes ~1.72-2.4 nm. A redshift of the plasmon peak with decreasing cluster size in the post-annealed samples is assigned to the 'spillout' effect (reduction of electron density) for clusters with ~157-427 number of Au atoms fully embedded in crystalline dielectric matrix with increased polarizability in the embedded system.