Enhanced Raman Scattering of ZnO Quantum Dots on Silver Colloids

Abstract

Enhancement of the Raman signals of ZnO quantum dots on Ag colloids was studied. Unique ZnO/Ag nanostructure materials were obtained by self-assembly of Ag nanocrystals using ZnO nanoparticles as seeds. The morphology and optical properties of ZnO/Ag core/shell particles are dependent on the quality of deposited Ag. The surface plasmon absorption band of Ag shifts toward lower energy due to the interaction between Ag and ZnO quantum dots. The intensities and orders of multiphonon fingerprint Raman lines of ZnO nanocrystals were increased remarkably from the effect of Ag. The efficient quantum dot excitation within the locally enhanced electromagnetic field produced by the silver nanoparticles is evidenced by the observation of the surface plasmon resonance in the enhanced Raman of ZnO nanocrystals.

Sonochemical synthesis and characterization of ZnO nanorod/Ag nanoparticle composites

“…These deficient electrons on the Ag surface consequently induce the broadening and red shifting of the surface plasmon band, consistent with previous reports that electron deficiency in metal nanoparticles shifts the surface plasmon band to a longer wavelength [32,33]. Shan et al reported the absorption features of ZnO quantum dot/Ag nanocomposites [34]. They found that the ultraviolet absorption of ZnO/Ag nanocomposites had no change and the visible absorption broadened, weakened and red-shifted, which implied that the ZnO quantum dots almost had no change in size and the interaction between ZnO quantum dots and Ag was weak.…”

Colloidal Strategies for Preparing Oxide‐Based Hybrid Nanocrystals

“…Also, multiphonon Raman scattering is enhanced by the strongly localized electromagnetic field of the metal plasmon, as observed in other types of composite systems. [106,107] These modified properties again reflect the mutual influence of interfacial electron communication that is achieved upon formation of a inorganic heterojunction.…”

Role of the support on the behavior of Ag-based catalysts for NH 3 selective catalytic oxidation (NH 3 -SCO)

“…In comparison with Ag/SiO 2 (385 nm) and Ag/NaY (390 nm) catalysts, the main characteristic surface plasma resonance (SPR) peaks of Ag 0 nanoparticles for Ag/Al 2 O 3 and Ag/TiO 2 samples show a large redshift to 450 nm and 500 nm, respectively. It has been known that the electron in Ag 0 surface can spill out of the classical radius and can be transferred into affinity levels of the support [28][29][30][31][32]. The spill-out of the electrons will lead to a decreased electron density and consequently the redshift of the Mie resonance frequency according to equation [29]:…”