The optical response of nanoclusters under confinement

Abstract

We report the optical properties of metallic and semiconductor nanoclusters with various sizes as a function of confinement using real-space time dependent density functional theory (TDDFT). The lowest equilibrium structures have been selected by examining the evolution of the lowest five isomers for each cluster as a function of volume for six different compressions. The minimum volume considered is about 1/10^th of the free space box volume. The absorption spectra depict a blue shift, an increase in intensity and a change in line shape of the spectral lines of the confined systems. The observed enhancement in the intensity of the spectral lines is found to be about two- to three-fold at high compression compared to their counterparts. This is accompanied by an increase in the optical band gap and excitation energy of the transitions with compression. In all of the systems that we investigate, the observed blue shift, an enhanced intensity and a change in line shape of the spectral lines are found to be generic in nature.