title: Growth of gold nanorods and bipyramids using CTEAB surfactant.
abstract: Gold nanorods and bipyramids have been synthesized using the seed-mediated approach in aqueous cetyltriethylammonium bromide (CTEAB) solutions in the presence of silver nitrate. Gold nanoparticle seeds that are stabilized with either CTEAB or sodium citrate have been used. The use of the CTEAB-stabilized seeds gives gold nanorods in high yield in one step with the longitudinal plasmon wavelength ranging from 750 to 1030 nm, depending on the amount of the seeds. The longitudinal plasmon wavelength can be extended to 1100 nm by the use of a two-step growth method. The growth of gold nanorods in CTEAB solutions takes 5-10 h, more than 5 times slower than that in cetyltrimethylammonium bromide solutions at the same concentration of surfactants. The use of the citrate-stabilized seeds gives both gold bipyramids and a small percentage of gold nanorods. The longitudinal plasmon wavelength of the bipyramids is tunable from 700 to 1100 nm by varying the amount of the citrate-stabilized seeds. The growth of gold bipyramids takes more than 1 day. Transmission electron microscopy characterizations reveal that the gold nanorods grown from both types of gold nanoparticle seeds are single-crystalline and that the gold bipyramids are penta-twinned.
authors.affiliation: Department of Physics, Chinese University of Hong Kong, Shatin, Hong Kong, China.
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Kou
authors.forename: Shuzhuo
authors.initials: S
authors.lastname: Zhang
authors.forename: Chia-Kuang
authors.initials: CK
authors.lastname: Tsung
authors.forename: Man Hau
authors.initials: MH
authors.lastname: Yeung
authors.forename: Qihui
authors.initials: Q
authors.lastname: Shi
authors.forename: Galen D
authors.initials: GD
authors.lastname: Stucky
authors.forename: Lingdong
authors.initials: L
authors.lastname: Sun
authors.forename: Jianfang
authors.initials: J
authors.lastname: Wang
authors.forename: Chunhua
authors.initials: C
authors.lastname: Yan