DCMPMS Seminars

Microcavity-enhanced investigation of nanoparticle dynamics

by Mr. SHALOM PALKHIVALA (Karlsruhe Institute of Technology, Germany)

Tuesday, August 16, 2022 from to (Asia/Kolkata)
at AG 80
We have developed a fibre-based high-finesse
Fabry-Perot microcavity capable of detecting and characterising single
unlabelled nanoparticles. Silica nanospheres with radii of 25 nm and
gold nanorods 20 nm in length have thus been detected in water.
Properties of the nanospheres such as the size, polarizability and
refractive index were deduced, and the three-dimensional Brownian
motion of a single nanoparticle in the cavity was tracked with spatial
and temporal resolutions as good as 8 nm and 0.3 ms respectively.
Furthermore, the rotation of nanoparticles could be measured using the
polarisation splitting of the resonance. When cavity scanning is too
slow to resolve small dynamic time constants, e.g. the rotation of
gold nanorods, measurement using an actively locked cavity can be used
to provide a high measurement bandwidth limited only by the detector
or the cavity linewidth. This additionally offers the advantages of
improved mechanical stability and drift compensation. Based on this,
we aim to investigate the optical and dynamic behaviour of single
biomolecules, such as DNA.