Branched Gold Nanochains Facilitated by Polyvinylpyrrolidone and their SERS Effects on p-Aminothiophenol

Stable gold nanochains with branched features were fabricated at room temperature with the assistance of polyvinylpyrrolidone (PVP). An attachment and fusion process was believed to responsible for the formation of the chain-like structure. During the process, PVP acted both as a structure-directing agent and as a stabilizer to inhibit continuous size increase. UV-vis-NIR study revealed that the unique structure shifted the longitudinal surface plasma resonant band (LSPR) to as far as 1457 nm, which may endow the product with new applications. The surface-enhanced Raman scattering activity was investigated with p-aminothiophenol as probe molecule. The enhancement factor (EF) of the products deposited as film on the Si substrate was estimated to be (1.03 +/- 0.74) x 10(6) for the a(1)-type band, while it was (1.32 +/- 0.15) x 10(7) for b(2)-type band. The enhancement of a, modes was attributed to the electromagnetic mechanism, whereas the additional EF for the b(2) mode is presumed to contribute from the chemical effect.