Journal Article

Sub-nanometre resolution in single-molecule photoluminescence imaging

Chen, Gong, Zhang, Yang, Ghafoor Atif, Sandoghdar Vahid, Hou, J G, Aizpurua Javier, Yang, Jinlong, Zhang, Yao, Luo, Yi, Zhang, Yufan, Dong Zhenchao, Yang, Ben

2020

Overview

Ambitions to reach atomic resolution with light have been a major force in shaping nano-optics, whereby a central challenge is achieving highly localized optical fields. A promising approach employs plasmonic nanoantennas, but fluorescence quenching in the vicinity of metallic structures often imposes a strict limit on the attainable spatial resolution, and previous studies have reached only 8 nm resolution in fluorescence mapping. Here, we demonstrate spatially and spectrally resolved photoluminescence imaging of a single phthalocyanine molecule coupled to nanocavity plasmons in a tunnelling junction with a spatial resolution down to ∼8 Å and locally map the molecular exciton energy and linewidth at sub-molecular resolution. This remarkable resolution is achieved through an exquisite nanocavity control, including tip-apex engineering with an atomistic protrusion, quenching management through emitter–metal decoupling and sub-nanometre positioning precision. Our findings provide new routes to optical imaging, spectroscopy and engineering of light–matter interactions at sub-nanometre scales.Through the use of a plasmon-active atomically sharp tip and an ultrathin insulating film, and precise junction control in a highly confined nanocavity plasmon field at the scanning tunnelling microscope junction, sub-nanometre-resolved single-molecule near-field photoluminescence imaging with a spatial resolution down to ∼8 Å is achieved.

• Publisher: Nature Publishing Group
• Subject: Decoupling / Emitters / Excitons / Fluorescence / Imaging / Luminescence / Microscopes / Nano-optics / Optics / Photoluminescence / Photons / Plasmons / Quenching / Spatial discrimination / Spatial resolution / Spectroscopy