Effective Plasmonic Coupling and Propagation Facilitates Ultrasensitive and Remote Sensing Using Surface Enhanced Raman Spectroscopy

Surface-enhanced Raman spectroscopy (SERS) is a sensitive technique for the detection of analytes through light scattering that is enhanced by chemical and electromagnetic effects through interactions on surfaces, particularly in nano-gaps. Herein we show that dissolved oxygen is the strongest attenuator of the SERS response in aqueous solution and its removal by chemical means can lower the detection limit by 109–1010 times, to achieve unprecedented sensitivity, i.e., detection of a single molecule in ~300 µL of sample solution. It also enables remote detection of the analyte outside of the field of view of the incident laser beam, e.g., over a distance of 1 m, which we propose is due to the coupling of the plasmonic field within and between nanoparticle aggregates, allowing for signal transmission throughout the sample volume.