Angle-resolved plasmonic photocapacitance of gold nanorod dimers

Pal, Sudip Kumar; Bardhan, Dorothy; Sen, Debarun; Chatterjee, Hirak; Ghosh, Sujit Kumar

doi:10.1039/d3na00061c

Cited by 2 publications

(1 citation statement)

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“…In the present work, we investigate rotational diffusion of small diffusing gold nanorods, , while they cross the near field of a larger, immobilized GNR, acting as a sensor . The plasmonic coupling − taking place between the sensor nanorod and the diffusing nanorod has the advantage of increasing the sensitivity with respect to a direct confocal detection, and of enabling the detection of smaller nanoparticles, which may be less perturbing for biomolecules, for example. Plasmonic coupling, however, has the disadvantage of further shortening the interaction time as the extent of the near field is much reduced in comparison to that of the confocal volume.…”

Section: Introductionmentioning

confidence: 99%

Exploring Rotational Diffusion with Plasmonic Coupling

Asgari,

Baaske,

Ton

et al. 2024

ACS Photonics

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Measuring the orientation dynamics of nanoparticles and nonfluorescent molecules in real time with optical methods is still a challenge in nanoscience and biochemistry. Here, we examine optoplasmonic sensing taking the rotational diffusion of plasmonic nanorods as an experimental model. Our detection method is based on monitoring the dark-field scattering of a relatively large sensor gold nanorod (GNR) (40 nm in diameter and 112 nm in length) as smaller plasmonic nanorods cross its near field. We observe the rotational motion of single small gold nanorods (three samples with about 5 nm in diameter and 15.5, 19.1, and 24.6 nm in length) in real time with a time resolution around 50 ns. Plasmonic coupling enhances the signal of the diffusing gold nanorods, which are 1 order of magnitude smaller in volume (about 300 nm 3 ) than those used in our previous rotational diffusion experiments. We find a better angular sensitivity with plasmonic coupling in comparison to the free diffusion in the confocal volume. Yet, the angle sensitivity we find with plasmonic coupling is reduced compared to the sensitivity expected from simulations at fixed positions due to the simultaneous translational and rotational diffusion of the small nanorods. To get a reliable plasmonic sensor with the full angular sensitivity, it will be necessary to construct a plasmonic assembly with positions and orientations nearly fixed around the optimum geometry.

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