Eagle-beak nanoantenna for non-blinking single molecule SERS via reversible preconcentration

Light interaction with nanoantenna causes induces a group oscillation of free electron on nanoantenna, and results in high-amplitude electric and temperature field near nanoantenna. The enhanced electric field (or hot-spot) has been importantly studied due to the potential in simple accomplishment of nonlinear optical phenomena (i.e. multiple-harmonic generation, two-photon absorption, surface-enhanced Raman scattering). Our proposed ‘eagle-beak’ nanoantenna also generates strongly focused electric field which enables single-molecule level detection in SERS. Furthermore, the thermal and electric field gradients from eagle-beak nanoantenna are designed to drive target molecules toward hot-spots, and are confirmed with numerical simulations. In experiments, eagle-beak nanoantenna showed highly stable and enhanced Raman scattering measurement with an enhancement factor of 10¹⁴. The reversible preconcentration causing the temporal stability of non-blinking, was verified by time-resolvable SERS spectra and fluorescence-based analysis. This study showing controllability of molecular motion by nanoantenna will expand to various applications of optoelectronics, solar cells and biophotonics.