Laser-Driven Plasmonic\nBubble Gold Nanorod Clusters\nwith ∼1 nm Gaps for Highly Sensitive SERS Detection

Surface-enhanced Raman spectroscopy (SERS) is closely\nrelated to\nthe SERS substrate. SERS substrate should not only possess small gaps\nto generate strongly enhanced hot spots but also facilitate the entry\nof target molecules into these hot spots. However, the presence of\nligands on the substrate can create steric hindrance, potentially\nimpeding the access of target molecules to hot spots. In this study,\nwe assembled a dense gold nanorod (AuNR) cluster with gaps of ∼1\nnm, utilizing laser-driven plasmonic bubbles. The AuNR cluster through\nlaser-driven plasmonic bubbles was accompanied by the reduction of\nthe ligands. The AuNR cluster can detect crystal violet solutions\nat concentrations as low as 10<sup>–12</sup> M and allows for\nthe SERS identification of various molecules. Furthermore, the practical\npotential of this AuNR cluster was demonstrated by the detection of\n10 ppb of paraquat on the tomatoes in situ. This work provides new\ninsights into the assembly of laser-driven plasmonic bubbles with\nnoble metal nanoparticles and their application in the field of SERS.