Oklahoma State University–Stillwater

About: Oklahoma State University–Stillwater is a education organization based out in Stillwater, Oklahoma, United States. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 18267 authors who have published 36743 publications receiving 1107500 citations. The organization is also known as: Oklahoma State University & OKState.

Layer-by-Layer Assembled Mixed Spherical and Planar Gold Nanoparticles: Control of Interparticle Interactions

Abstract: Gold nanoparticles (NPs) were prepared by reduction with salicylic acid in aqueous solution. The resulting dispersions were found to contain a mixture of flat triangular/hexagonal and smaller close-to-spherical NPs. As expected from theoretical considerations, such nanocolloids display two clearly differentiated surface plasmon bands at 540 and 860 nm associated with spherical and anisotropic triangular/hexagonal NPs, respectively. Layer-by-layer (LBL) assembly was used to deposit thin films of the Au colloids. UV−visible data indicate preferential adsorption of the flat particles on polyelectrolyte films. Importantly, a new band developed at 650 nm as the number of the Au NPs bilayers increased. This finding indicates that there exists a strong interaction between the NPs in adjacent layers, resulting in the surface plasmon absorption at a new wavelength. The insertion of extra polyelectrolyte or montmorillonite layers between the Au bilayers was shown to gradually reduce the interlayer interaction and r...

“Raisin Bun”-Type Composite Spheres of Silica and Semiconductor Nanocrystals

Abstract: CdTe nanocrystals capped with 1-mercapto-2,3-propandiol, CdSe nanocrystals capped with sodium citrate, and core−shell CdSe/CdS nanocrystals capped with sodium citrate were synthesized in aqueous solutions, and their surface was modified by 3-mercaptopropyltrimethoxysilane (MPS) in water−ethanol mixtures. By addition of sodium silicate, “raisin bun”-type composite particles were formed, with either CdTe, CdSe, or CdSe/CdS nanocrystals being homogeneously incorporated as multiple cores into silica spheres of 40−80 nm size, accompanied by some alteration of optical properties of the nanoparticles and, in particular, the reduction of the luminescence quantum yield. Further, growth of larger silica spheres (100−700 nm) can be performed by the Stober technique using either MPS-modified semiconductor nanocrystals or “raisin bun”-type composite particles as seeds, which gives semiconductor-doped silica globules of desirable sizes in the submicrometer range. The composite spheres can be used as building blocks for...