Brownian fluctuations of an optically rotated nanorod
Journal article, 2017

Gold nanorods can be optically trapped in aqueous solution and forced to rotate at kilohertz rates by circularly polarized laser light. This enables detailed investigations of local environmental parameters and processes, such as medium viscosity and nanoparticle-molecule reactions. Future applications may include nanoactuation and single-cell analysis. However, the influence of photothermal heating on the nanoparticle dynamics needs to be better understood in order to realize widespread and quantitative use. Here we analyze the hot Brownian motion of a rotating gold nanorod trapped in two dimensions by an optical tweezers using experiments and stochastic simulations. We show that, for typical settings, the effective rotational and translational Brownian temperatures are drastically different, being closer to the nanorod surface temperature and ambient temperature, respectively. Further, we show that translational dynamics can have a non-negligible influence on the rotational fluctuations due to the small size of a nanorod in comparison to the focal spot. These results are crucial for the development of gold nanorods into generic and quantitative optomechanical sensor and actuator elements.


Faegheh Hajizadeh Chavari

Chalmers, Physics

Lei Shao

Chalmers, Physics

Daniel Andrén

Chalmers, Physics, Bionanophotonics

Peter Johansson

Chalmers, Physics

Halina Rubinsetein

Chalmers, Physics

Mikael Käll

Chalmers, Physics, Bionanophotonics


2334-2536 (ISSN)

Vol. 4 7 746-751

Subject Categories

Atom and Molecular Physics and Optics



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