Ultrasensitive surface-enhanced Raman spectroscopy using directionally arrayed gold nanoparticle dimers

This paper reports an ultrasensitive nanostructure for surface-enhanced Raman spectroscopy (SERS). The gold nanoparticle dimer, which has been reported as the highest Raman enhancing structure, was directionally arrayed on a substrate for the first time. The highest enhancement can be achieved when a particle connection direction of a dimer is matched to polarization direction of incident light. Therefore the huge enhancement can be achieved at all dimers in total. Optimizing the dimer arrangement, 10 pM limit of detection and 0.5 s rapid detection were achieved.