Sub-nanometre resolution in single-molecule photoluminescence imaging

• Published in: Nature photonics Vol. 14; no. 11; pp. 693 - 699
• Main Authors: Yang, Ben, Chen, Gong, Ghafoor, Atif, Zhang, Yufan, Zhang, Yao, Zhang, Yang, Luo, Yi, Yang, Jinlong, Sandoghdar, Vahid, Aizpurua, Javier, Dong, Zhenchao, Hou, J. G.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-11-2020; Nature Publishing Group
• Subjects: 639/624/1107/510; 639/624/1107/527/1819; 639/638/439/945; 639/766/400/1021; 639/925/930/527/1819; Applied and Technical Physics; Decoupling; Emitters; Excitons; Fluorescence; Imaging; Luminescence; Microscopes; Nano-optics; Optics; Photoluminescence; Photons; Physics; Physics and Astronomy; Plasmons; Quantum Physics; Quenching; Spatial discrimination; Spatial resolution; Spectroscopy
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-020-0677-y

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.