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Resonant scattering-enhanced photothermal microscopy.

Authors
  • Li, Qiang1
  • Shi, Zhonghong1
  • Wu, Lijun1
  • Wei, Hong2
  • 1 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, China. [email protected] , (China)
  • 2 Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. [email protected] and Songshan Lake Materials Laboratory, Dongguan 523808, China. , (China)
Type
Published Article
Journal
Nanoscale
Publisher
The Royal Society of Chemistry
Publication Date
Apr 02, 2020
Identifiers
DOI: 10.1039/c9nr10893a
PMID: 32239001
Source
Medline
Language
English
License
Unknown

Abstract

Photothermal (PT) microscopy is currently the most efficient approach for the detection and spectroscopy of individual non-fluorescent nano-objects based solely on their absorption. The nano-objects in current PT microscopy are usually non-resonant with the probe laser light, and the PT signal is mainly generated from the interactions of the incident probe light and the heating light-induced thermal lens around the imaged object. Inspired by the high sensitivity of the scattering field from the nano-objects near optical resonance to the variation in the local refractive index, we developed a novel strategy of resonant scattering-enhanced PT microscopy where the imaged nano-objects are near-resonant with the probe laser light. We have demonstrated this by using gold nanorods (NRs) with tunable longitudinal surface plasmon resonances. The PT signal of gold NR near-resonant with the probe light showed dramatic variation in the narrow resonance wavelength range, as small as 15 nm, and the maximal amplitude of the PT signal in this range can be enhanced up to 43 times as compared with the weak PT signal of gold NR non-resonant with the probe light. Theoretical analysis indicates that the obtained strong PT signal is mainly caused by the heat-induced variation in the polarizability of gold NR. Our novel work demonstrates the first resonant scattering-enhanced PT imaging of plasmonic nanoparticles, paving the way for the development of PT microscopy with ultra-high sensitivity toward the sensing, imaging, and spectroscopy of nanoscopic objects in complex environments.

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