NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge , Cambridge CB3 0HE, United Kingdom.
Faculty of Arts and Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
Nano Lett. 2017 Apr 12;17(4):2568-2574. doi: 10.1021/acs.nanolett.7b00332. Epub 2017 Mar 17.
The mechanism by which light is emitted from plasmonic metals such as gold and silver has been contentious, particularly at photon energies below direct interband transitions. Using nanoscale plasmonic cavities, blue-pumped light emission is found to directly track dark-field scattering on individual nanoconstructs. By exploiting slow atomic-scale restructuring of the nanocavity facets to spectrally tune the dominant gap plasmons, this correlation can be measured from 600 to 900 nm in gold, silver, and mixed constructs ranging from spherical to cube nanoparticles-on-mirror. We show that prompt electronic Raman scattering is responsible and confirm that "photoluminescence", which implies phase and energy relaxation, is not the right description. Our model suggests how to maximize light emission from metals.
从等离子体金属（如金和银）中发射光的机制一直存在争议，特别是在光子能量低于直接带间跃迁的情况下。使用纳米级等离子体腔，发现蓝光泵浦光发射直接跟踪单个纳米结构的暗场散射。通过利用纳米腔面的原子尺度缓慢重构来对主要的间隙等离子体进行光谱调谐，这种相关性可以在金、银和混合结构（从球形到立方体纳米粒子在镜面上）中从 600nm 到 900nm 进行测量。我们表明，快速电子拉曼散射是负责的，并确认“光致发光”（暗示相位和能量弛豫）不是正确的描述。我们的模型表明如何最大限度地提高金属的发光效率。
