title: Ultrasmall hollow gold-silver nanoshells with extinctions strongly red-shifted to the near-infrared.
abstract: Hollow gold-silver nanoshells having systematically varying sizes between 40 and 100 nm were prepared. These particles consist of a hollow spherical silver shell surrounded by a thin gold layer. By varying the volume of the gold stock solution added to suspensions of small silver-core templates, we tailored the hollow gold-silver nanoshells to possess strong tunable optical extinctions that range from the visible to the near-IR spectral regions, with extinctions routinely centered at ∼950 nm. The size and morphology of these core/shell nanoparticles were characterized by dynamic light scattering (DLS), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Separately, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used for measuring their elemental composition; UV-vis spectroscopy was used to evaluate their optical properties. Given their relatively small size compared to other nanoparticles that absorb strongly at near IR wavelengths, these easy-to-synthesize particles should find use in applications that require ultrasmall nanoparticles with extinctions comfortably beyond visible wavelengths (e.g., medicinal therapies, diagnostic imaging, nanofluidics, and display technologies).
authors.affiliation: Department of Chemistry, University of Houston, 4800 Calhoun Road, Houston, Texas 77204-5003, United States.
authors.forename: Varadee
authors.initials: V
authors.lastname: Vongsavat
authors.forename: Brandon M
authors.initials: BM
authors.lastname: Vittur
authors.forename: William W
authors.initials: WW
authors.lastname: Bryan
authors.forename: Jun-Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: T Randall
authors.initials: TR
authors.lastname: Lee
mesh_terms: D006046:Gold / Q000737:chemistry*; D057145:Nanoshells / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D056951:Photoelectron Spectroscopy; D012834:Silver / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D019265:Spectroscopy, Near-Infrared; D014961:X-Ray Diffraction
chemical_list: D012834:Silver; D006046:Gold