Optical traps have many interesting applications in chemistry and biology as they have the ability to capture and manipulate micro and nano scale objects.  As smaller nanoscale particles are impossible to image using traditional methods physical processes are used to confirm particle presence.  One such method for detecting gold nanoparticles is to monitor their plasmonic response and scattering.  Our research focuses on the trapping and characterization of gold nanoparticles by way of this mechanism.  The plasmonic response arises from the displacement of the electrons in the particle as they interact with the electric field of the light.  We use a Galvo Scanning Mirror to generate particle movement measuring the optical signal to deduce particle size and trap stiffness.  The illumination source is folded into the primary optical path in tandem with the trapping laser to illuminate the particle in the trapping plane.  As the particle moves through the shallow depth of focus due to the high NA of a microscope objective there is a discernable “flashing” signal of the 532 nm light that can be analyzed by using a photodiode.  Quantitative analysis can then be done to determine unique properties extracted from the signal.  Utilizing this method particle characteristics are determined through a fitting technique that equates particle size with focal plane signal intensity.  This method can be used to determine that a particle is trapped and also the physical size characteristics that can achieve more precise results in secondary data analysis that uses particles size as an input.<br/>

Quantitative size characterization of trapped gold nanoparticles through plasmonic properties

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.