The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, UK.
Physical Chemistry I, Department of Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstrasse 5, 45141 Essen, Germany.
Nat Commun. 2017 Mar 28;8:14880. doi: 10.1038/ncomms14880.
Nanoscale localization of electromagnetic fields near metallic nanostructures underpins the fundamentals and applications of plasmonics. The unavoidable energy loss from plasmon decay, initially seen as a detriment, has now expanded the scope of plasmonic applications to exploit the generated hot carriers. However, quantitative understanding of the spatial localization of these hot carriers, akin to electromagnetic near-field maps, has been elusive. Here we spatially map hot-electron-driven reduction chemistry with 15 nm resolution as a function of time and electromagnetic field polarization for different plasmonic nanostructures. We combine experiments employing a six-electron photo-recycling process that modify the terminal group of a self-assembled monolayer on plasmonic silver nanoantennas, with theoretical predictions from first-principles calculations of non-equilibrium hot-carrier transport in these systems. The resulting localization of reactive regions, determined by hot-carrier transport from high-field regions, paves the way for improving efficiency in hot-carrier extraction science and nanoscale regio-selective surface chemistry.
纳米尺度下金属纳米结构附近电磁场的局域性是等离子体学的基础和应用。最初被视为不利因素的等离子体衰减引起的不可避免的能量损失，现在已经扩展了等离子体应用的范围，以利用产生的热载流子。然而，对于这些热载流子的空间局域性的定量理解，类似于电磁场近场图，一直难以捉摸。在这里，我们以不同的等离子体纳米结构为研究对象，通过实验与理论相结合的方法，以 15nm 的分辨率、随时间和电磁场极化的函数关系，对热电子驱动的还原化学进行了空间映射。我们采用了一个六电子光循环过程，该过程修饰了等离子体银纳米天线自组装单分子层的端基，同时还基于第一性原理计算预测了这些系统中非平衡热载流子输运的理论。反应区的定位由从高场区输运的热载流子决定，这为提高热载流子提取科学和纳米尺度区域选择性表面化学的效率铺平了道路。
