In‐Situ Partial Sintering of Gold‐Nanoparticle Sheets for SERS Applications

Abstract A new, versatile substrate design for surface‐enhanced Raman spectroscopy (SERS) is introduced that provides better illumination and collection efficiency than other solid substrates. It uses sheets of 5 nm diameter gold nanoparticles that are draped by drying‐mediated self‐assembly onto 100 nm thick silicon nitride membranes. During laser illumination, partial in‐situ sintering of the nanoparticles into larger structures with tiny gaps (≈2 nm) greatly increases the SERS enhancement factor. The detection of 1 pM of p‐mercaptoaniline and 1 fg of 2,4‐dinitrotoluene is demonstrated. The use of self‐assembled nanoparticle sheets furthermore makes it possible to perform SERS detection in situ on top of a probe solution droplet.