From Springer Nature via Jisc Publications RouterHistory: received 2021-01-14, accepted 2021-06-16, registration 2021-07-13, pub-electronic 2021-07-27, online 2021-07-27, collection 2021-12Publication status: PublishedFunder: EC | EU Framework Programme for Research and Innovation H2020 | H2020 Priority Excellent Science | H2020 European Research Council (H2020 Excellent Science - European Research Council); doi: https://doi.org/10.13039/100010663; Grant(s): 741431-2DNanoSpecFunder: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (Swiss National Science Foundation); doi: https://doi.org/10.13039/501100001711; Grant(s): URPP-LightChECFunder: EC | Horizon 2020 Framework Programme (EU Framework Programme for Research and Innovation H2020); doi: https://doi.org/10.13039/100010661; Grant(s): 841653-2DvdWHsFunder: the Swiss National Supercomputing Centre (CSCS) under Project ID uzh1 and s965Abstract: Plasmon-induced chemical reactions (PICRs) have recently become promising approaches for highly efficient light-chemical energy conversion. However, an in-depth understanding of their mechanisms at the nanoscale still remains challenging. Here, we present an in-situ investigation by tip-enhanced Raman spectroscopy (TERS) imaging of the plasmon-induced [4+4]-cycloaddition polymerization within anthracene-based monomer monolayers physisorbed on Au(111), and complement the experimental results with density functional theory (DFT) calculations. This two-dimensional (2D) polymerization can be flexibly triggered and manipulated by the hot carriers, and be monitored simultaneously by TERS in real time and space. TERS imaging provides direct evidence for covalent bond formation with ca. 3.7 nm spatial resolution under ambient conditions. Combined with DFT calculations, the TERS results demonstrate that the lateral polymerization on Au(111) occurs by a hot electron tunneling mechanism, and crosslinks form via a self-stimulating growth mechanism. We show that TERS is promising to be plasmon-induced nanolithography for organic 2D materials
