title: Synthesis of Ag nanobars in the presence of single-crystal seeds and a bromide compound, and their surface-enhanced Raman scattering (SERS) properties.
abstract: This Article describes the synthesis of Ag nanobars with different aspect ratios using a seed-mediated method and evaluation of their use for surface-enhanced Raman scattering (SERS). The formation of Ag nanobars was found to critically depend on the introduction of a bromide compound into the reaction system, with ionic salts being more effective than covalent molecules. We examined single-crystal seeds with both spherical and cubic shapes and found that Ag nanobars grown from spherical seeds had much higher aspect ratios than those grown from cubic seeds. The typical product of a synthesis contained nanocrystals with three different morphologies: nanocubes, nanobars with a square cross section, and nanobars with a rectangular cross section. Their formation can be attributed to the difference in growth rates along the three orthogonal <100> directions. The SERS enhancement factor of the Ag nanobar was found to depend on its aspect ratio, its orientation relative to the laser polarization, and the wavelength of excitation.
authors.affiliation: Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130, United States.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Christine H
authors.initials: CH
authors.lastname: Moran
authors.forename: Xiaohu
authors.initials: X
authors.lastname: Xia
authors.forename: Matthew
authors.initials: M
authors.lastname: Rycenga
authors.forename: Naixu
authors.initials: N
authors.lastname: Li
authors.forename: Younan
authors.initials: Y
authors.lastname: Xia
mesh_terms: D001965:Bromides / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D013499:Surface Properties
chemical_list: D001965:Bromides; D012834:Silver