Spectroscopic investigations on the orientation of 1,4-dibromonaphthalene on silver nanoparticles

Silver nanoparticles (Ag NPs) have been prepared by solution combustion method with glycine as fuel. Silver nanoparticles were characterized by X-Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and UV-visible spectroscopy. The prepared silver nanoparticles exhibit cubic crystalline structure with grain size of 59 nm. HRTEM image shows that the silver nanoparticles have strain and four-fold symmetry formed by twinning in the crystal structure. The optical adsorption spectrum shows that the surface plasmon resonance peak of silver is observed at 380 nm. The orientation of 1,4-dibromonaphthlaene (1,4-DBrN) on silver nanoparticles has been inferred from nRs and SERS spectral features. The absence of a C-H stretching vibrations, the observed high intense C-H out-of-plane bending modes and high intense C-Br stretching vibration suggest that the 1,4-DBrN molecule may be adsorbed in a 'stand-on' orientation to the surface.