Improve the surface-enhanced Raman scattering from rhodamine 6G adsorbed gold nanostars with vimineous branches

•The SERS ability greatly depends on the infrared plasmonic absorption of Au nanostars.•The infrared absorption indicates the increase of the branch number and aspect ratio.•The lightning rod effect from the branches of Au nanostars improves the SERS.

The surface-enhanced Raman scattering (SERS) activity of the gold nanostars with vimineous branches has been investigated by using rhodamine 6G (R6G) as the Raman active probe. The colloidal gold nanostars have two intense localized surface plasmon resonance (LSPR) peaks in the visible and infrared ranges, respectively. Besides the visible LSPR dependent local field effect induced Raman signal enhancement, the SERS ability also greatly depends on the infrared absorption from the plasmon resonance along the aligned branches. Whether increasing the peak intensity or wavelength of the infrared absorption leads to the efficient improvement of SERS. These correlations between plasmonic absorption and SERS indicate that the lightning rod effect and creation of hot spots have been enhanced with the length and number of gold branches.