Hot electrons in water: injection and ponderomotive acceleration by means of plasmonic nanoelectrodes  

作　　者：Pierfrancesco Zilio Michele Dipalo Francesco Tantussi Gabriele C Messina Francesco de Angelis 

机构地区：[1]Istituto Italiano di Tecnologia,16163,Genova,Italy

出　　处：《Light(Science & Applications)》2017年第1期744-751,共8页光（科学与应用)（英文版）

基　　金：the European Research Council under the European Union’s Seventh Framework Program(FP/2007-2013)/ERC Grant Agreement No.[616213];CoG:Neuro-Plasmonics and under the Horizon 2020 Program,FET-Open:PROSEQO,Grant Agreement No.[687089].

摘　　要：We present a theoretical and experimental study of a plasmonic nanoelectrode architecture that is able to inject bunches of hot electrons into an aqueous environment.In this approach,electrons are accelerated in water by ponderomotive forces up to energies capable of exciting or ionizing water molecules.This ability is enabled by the nanoelectrode structure(extruding out of a metal baseplate),which allows for the production of an intense plasmonic hot spot at the apex of the structure while maintaining the electrical connection to a virtually unlimited charge reservoir.The electron injection is experimentally monitored by recording the current transmitted through the water medium,whereas the electron acceleration is confirmed by observation of the bubble generation for a laser power exceeding a proper threshold.An understanding of the complex physics involved is obtained via a numerical approach that explicitly models the electromagnetic hot spot generation,electron-by-electron injection via multiphoton absorption,acceleration by ponderomotive forces and electron-water interaction through random elastic and inelastic scattering.The model predicts a critical electron density for bubble nucleation that nicely matches the experimental findings and reveals that the efficiency of energy transfer from the plasmonic hot spot to the free electron cloud is much more efficient(17 times higher)in water than in a vacuum.Because of their high kinetic energy and large reduction potential,these proposed wet hot electrons may provide new opportunities in photocatalysis,electrochemical processes and hot-electron driven chemistry.

关 键 词：hot electrons hydrated electrons lightwave electronics PLASMONICS ponderomotive acceleration strong-field photoemission water breakdown 

分 类 号：O57[理学—粒子物理与原子核物理]