Enantioselective Optical Trapping of Chiral Nanoparticles with Plasmonic Tweezers

Yang Zhao, Amr A.E. Saleh, Jennifer A. Dionne

Research output: Contribution to journalArticlepeer-review

Abstract

Enantiomer separation is a critical step in many chemical syntheses, particularly for pharmaceuticals, but prevailing chemical methods remain inefficient. Here, we introduce an optical technique to sort chiral specimens using coaxial plasmonic apertures. These apertures are composed of a deeply subwavelength silica channel embedded in silver and can stably trap sub-20 nm dielectric nanoparticles. Using both full-field simulations and analytic calculations, we show that selective trapping of enantiomers can be achieved with circularly polarized illumination. Opposite enantiomers experience distinct trapping forces in both sign and magnitude: One is trapped in a deep potential well, while the other is repelled with a potential barrier. These potentials maintain opposite signs across a range of chiral polarizabilities and enantiomer-aperture separations. Our theory indicates that the interaction of chiral light and chiral specimens can be mediated by achiral plasmonic apertures, providing a possible route toward all-optical enantiopure syntheses.

Original languageEnglish (US)
Pages (from-to)304-309
Number of pages6
JournalACS Photonics
Volume3
Issue number3
DOIs
StatePublished - Mar 16 2016
Externally publishedYes

Keywords

  • chiral molecules
  • enantiomer separation
  • nano-optical tweezers
  • optical forces

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biotechnology
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

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