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 Au-C 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 Au-C 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 Au-C band, and offer promising alternative to thiol compounds for anchoring organic molecules to gold surface to form self-assembled monolayers. (C) 2014 Elsevier B.V. All rights reserved.