‘Spillout’ effect in gold nanoclusters embedded in c-Al2O3(0 0 0 1) matrix

Gold nanoclusters are grown by 1.8 MeV Au2+ implantation on c-Al2O2(0 0 0 1) substrate and subsequent air annealing at temperatures ⩾1273 K. Post-annealed samples show plasmon resonance in the optical (579–561 nm) region for average cluster radius ∼0.86–1.2 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.