Optimizing surface-enhanced Raman scattering by template guided assembling of closely spaced silver nanocluster arrays

We present an easy approach to synthesize closely spaced regular arrays of silver nanoclusters, which are self-assembled by depositing gas-phase synthesized metal nanoclusters onto pre-patterned triblock copolymer templates. The array has a high particle density of about 2 ×103 particles per μm2, and an average interparticle space of about 20 nm. The surface plasmon resonance wavelength of the array is tuned due to the interparticle plasmon coupling. High SERS sensitivity for less than one layer trans-1,2-bi-(4-pyridyl) ethylene (BPE) molecule detection, with an enhancement factor of 2.6 ×106, has been demonstrated for a substrate with this array. The enhanced Raman signal was found to be 5 times higher than that measured from the substrate with randomly distributed silver nanoparticles.