Au@Phenyacetylene organogold clusters: direct spectroscopic evidence of gold-carbon covalent band.

Surface-enhanced Raman Scattering (SERS) as a powerful vibrational spectroscope technique is used to investigate the existence of AuC band between gold nanoparticles (AuNPs) and phenylacetylene (PA) which is characterized by a new Raman-active peak at 405 cm(-1). The measurements with transmission electron microscopy (TEM) and extinction spectroscopy show an increasing in size and spectral redshift for AuNPs after the addition of the PA molecule demonstrating the production of gold-PA organogold cluster (Au:C₂Ph). Furthermore, a strong band characteristic of AuC stretch mode is observed in the SERS spectra of Au:C₂Ph and supported by the density functional theory (DFT) calculation. In addition, the optimal adsorption of PA on AuNPs' surface is also investigated theoretically. These findings show a direct spectroscopic sight into AuC band, and offer promising alternative to thiol compounds for anchoring organic molecules to gold surface to form self-assembled monolayers.