Coulomb attraction driven spontaneous molecule-hotspot pairing enables universal, fast, and large-scale uniform single-molecule Raman spectroscopy

Raman spectroscopy offers a great power to detect, analyze and identify molecules, and monitor their temporal dynamics and evolution when combined with single-molecule surface-enhanced Raman scattering (SM-SERS) substrates. Here we present a SM-SERS scheme that involves simultaneously giant chemical enhancement from WS₂ 2D materials, giant electromagnetic enhancement from plasmonic nanogap hot spot, and inhibition of molecular fluorescence influence under near-infrared laser illumination. Remarkably we find Coulomb attraction between analyte and gold nanoparticle can trigger spontaneous formation of molecule-hotspot pairing with high precision, stability and robustness. The scheme has enabled realization of universal, robust, fast, and large-scale uniform SM-SERS detection for three Raman molecules of rhodamine B, rhodamine 6G, and crystal violet with a very low detection limit of 10⁻¹⁶ M and at a very fast spectrum acquisition time of 50 ms.