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Article Dans Une Revue Applied Physics Letters Année : 2021

Direct imaging of fluorescence enhancement in the gap between two gold nanodisks

Hengyang Xiang
  • Fonction : Auteur
Chenghao Xin
  • Fonction : Auteur
Zhelu Hu
  • Fonction : Auteur
Laurent Billot
Patrick Gredin
  • Fonction : Auteur
Michel Mortier
  • Fonction : Auteur
Zhuoying Chen
Maria-Ujué González
Antonio García- Martín
  • Fonction : Auteur
Lionel Aigouy

Résumé

We present an analysis of the optical coupling between two gold nanodisks by near-field fluorescence microscopy. This is achieved by scanning and measuring simultaneously the light emitted by a single Er3+/Yb3+ doped nanocrystal glued at the end of an atomic force microscope tip. The excitation of the nanocrystal was performed at  = 975 nm, via up-conversion, and fluorescence was detected in the visible part of the spectrum at  = 550 nm. For an isolated nanodisk, the near-field presents a two-lobe pattern oriented along the direction of the incident polarization. For two nanodisks with a sizeable separation distance (385 nm), illuminated with the polarization along the interparticle axis, we observe a negative effect of the coupling with a slight decrease of fluorescence in the gap. For smaller gap values (195 nm, 95 nm and 55 nm) a strong increase of fluorescence is observed as well as a reduced spatial localization of the field as the distance decreases. Finally, when the disks touch each other (0 nm), the dipolar-dipolar interaction between them disappears, and no fluorescence enhancement occurs. A new plasmon mode is created, at another wavelength. Our experimental results are in good agreement with numerical simulations of the near-field intensity distribution at the excitation wavelength on the surface of the structures. Combining fluorescence mapping and far-field scattering spectroscopy should be of strong interest to develop bio-chemical sensors based on field enhancement effects.
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Dates et versions

hal-03372826 , version 1 (11-10-2021)

Identifiants

Citer

Hung-Ju Lin, Hengyang Xiang, Chenghao Xin, Zhelu Hu, Laurent Billot, et al.. Direct imaging of fluorescence enhancement in the gap between two gold nanodisks. Applied Physics Letters, 2021, 118 (16), pp.161105. ⟨10.1063/5.0049395⟩. ⟨hal-03372826⟩
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