Orientation of 1,4-dimethoxy-3–bromomethylanthracence-9,10-dione on silver nanoparticles: SERS studies

Silver nanoparticles (Ag NPs) are prepared by solution combustion method with glycine as fuel. Silver nanoparticles are characterized by UV–visible spectroscopy, X-ray Diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM). The optical adsorption spectrum shows that the surface plasmon resonance peak of silver is observed at 380 nm. The prepared silver nanoparticles exhibit cubic crystalline structure with grain size of 59 nm. HRTEM image shows that the silver nanoparticles have strain and fivefold symmetry is formed by twinning in the crystal structure. Surface-enhanced Raman scattering (SERS) of 1,4-dimethoxy-3-bromomethyl-9,10anthraquinone dione (DMBMAD) adsorbed on silver nanoparticles has been investigated. The orientation of DMBMAD on silver nanoparticles has been inferred from nRs and SERS spectral features. The observed spectral feature corroborated that DMBMAD would absorb on silver surface with ‘stand-on’ orientation through the high intensity of CH out-of-plane bending mode, CBr stretching, ring stretching and CO. In present case we used the DMBMAD and Ag NPs as component molecules for energy gap analysis, whereas DMBMAD serve as donor and Ag NPs as acceptor. The calculated HOMO and LUMO energy gap shows that charge transfer occur within molecule and Ag NPs.