Laser rapid thermal annealing enables tunable plasmonics in nanoporous gold nanoparticles

A novel laser rapid thermal annealing (LRTA) technique is reported to tune the plasmonic resonance of disk-shaped nanoporous gold (NPG) nanoparticles for the first time. LRTA alters both the external and internal geometrical parameters of NPG nanoparticles at temperatures significantly lower than the melting temperature of bulk gold or non-porous gold nanoparticles. With increasing annealing laser intensity, the average pore size increases, while the mean disk diameter decreases. These morphological changes lead to blueshifting of the localized surface plasmon resonance (LSPR), which subsequently fine-tunes the SERS performance by better aligning the excitation laser and Raman scattering wavelengths with the LSPR peak. This technique can provide an effective means to optimize NPG nanoparticles for various plasmonic applications such as photothermal conversion, light-gated molecular release, and molecular sensing.