Theoretical Studies on Functionalized Graphene-Metal Cluster Interactions

Functionalized graphene – metal nano-cage hybrid platforms are used in recent years for trace level identification of explosives and environment contaminating materials using Raman fingerprints. In the present project, nature of interactions of functionalized graphene systems with model metal (Au₄ and Ag₄) clusters are investigated using state of the art density functional theories (DFT) including B3LYP functional and LANL2DZ basis set of atoms. Functionalized (5, 5)-graphene sheets are initially modeled with full geometry optimization and gold and silver clusters (Au₄ and Ag₄) are attached to the functional sites (with full geometry optimizations). The affinities of such clusters towards these systems are computed in terms of interaction energies. Vibrational analysis is carried out to confirm the nature of the computed geometries.  Pyridine is attached to these model systems and Raman spectrum is computed for these complexes to monitor the nature of Pyridine vibrations. Isolated pyridine has very weak Raman intensity (RI). The chemical effect due to such attachments increases the RI of important Raman modes several times. The results show that such models pave way to generate the further increase of RIs of pyridine through resonance/surface further enhanced Raman spectroscopy and could prove to be an alternate way of detecting such molecules.