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Plasmonic coupling of two optically trapped particles

Background and Problem: Two small metallic particles diffusing inside an optical trap cannot be imaged or tracked separately. Therefore, the fast interaction between both particles is not resolvable. However, when the particles get into contact plasmonic coupling can be measured by a red shift of the resonant spectrum.
 
Approach: We combine1 MHz 3D BFP-interferometry from the 1064nm trapping laser light with 500 Hz plasmonic spectrometry and analyse the dynamics of up to five 80nm silver spheres inside a single optical point trap. From the correlations between spectral changes and the changes in the interferometric signals, we can recover the intermediate formation of dimers, trimers and other binding configurations.
 
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Publications
 

Blattmann M, Rohrbach A
Plasmonic Coupling Dynamics of Silver Nanoparticles in an Optical Trap
2015 Nano Lett, Band: 15, Seiten: 7816 - 7821

Kermani H, Rohrbach A
Orientation-control of two plasmonically-coupled nanoparticles in an optical trap
2018 ACS Photonics

 

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