A TD-DFT Study of the Spectroscopic Properties of Hollow Silver Cluster

Noble metal clusters have attracted the interest of the scientific community for their particular electronic and optical properties, which are remarkably size-dependent. In fact, these systems have great potentials for technological applications such as in the development of optical devices or for medical applications, in diagnostic and therapeutic fields. As an example, in the latter case the metal nanoparticles need to be tailored in order to have strong absorption in the near infrared (NIR), since biological tissues are transparent in this spectral region. For these reasons, great efforts have been invested in developing synthetic methods to control the parameters that dictate the nanostructure applicability like shape, stability, composition and size. In this framework, the theoretical modeling can be applied for correlating the electronic and structural properties with the size and composition of these systems, in order to achieve information about the design and the tuning of the optical absorptions of the noble metal clusters. Recently, improvements in the descriptions of the relationships between structure and electronic properties were achieved for nanorod and spherical Ag clusters, using the density functional theory. Here, we extend these results to hollow nanorods and nanocages, i.e. non classic structures, demostrating that our model can predict satisfactory the formation of low-energy transitions, experimentally observed in the NIR region.