Discriminatory optical force for chiral molecules

Robert Cameron, Steve Barnett, Alison Yao

Research output: Contribution to journalArticle

86 Citations (Scopus)
62 Downloads (Pure)

Abstract

We suggest that the force F exerted upon a chiral molecule by light assumes the form F = aw + bh under appropriate circumstances, where a and b pertain to the molecule whilst w and h are the local densities of electric energy and helicity in the optical field; the gradients ∇ of these quantities thus governing the molecule’s centre-of-mass motion. Whereas a is identical for the mirror- image forms or enantiomers of the molecule, b has opposite signs; the associated contribution to F therefore pointing in opposite directions. A simple optical field is presented for which ∇w vanishes but ∇h does not, so that F is absolutely discriminatory. We then present two potential applications: a Stern–Gerlach-type deflector capable of spatially separating the enantiomers of a chiral molecule and a diffraction grating to which chiral molecules alone are sensitive; the resulting diffraction patterns thus encoding information about their chiral geometry.

Original languageEnglish
Article number013020
Number of pages18
JournalNew Journal of Physics
Volume16
Issue numberJanuary
DOIs
Publication statusPublished - 15 Jan 2014

Fingerprint

molecules
enantiomers
deflectors
gratings (spectra)
center of mass
coding
diffraction patterns
mirrors
gradients
geometry
energy

Keywords

  • chiral molecules
  • medical physics
  • optical trapping

Cite this

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Discriminatory optical force for chiral molecules. / Cameron, Robert; Barnett, Steve; Yao, Alison.

In: New Journal of Physics, Vol. 16, No. January, 013020, 15.01.2014.

Research output: Contribution to journalArticle

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AU - Cameron, Robert

AU - Barnett, Steve

AU - Yao, Alison

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AB - We suggest that the force F exerted upon a chiral molecule by light assumes the form F = a∇w + b∇h under appropriate circumstances, where a and b pertain to the molecule whilst w and h are the local densities of electric energy and helicity in the optical field; the gradients ∇ of these quantities thus governing the molecule’s centre-of-mass motion. Whereas a is identical for the mirror- image forms or enantiomers of the molecule, b has opposite signs; the associated contribution to F therefore pointing in opposite directions. A simple optical field is presented for which ∇w vanishes but ∇h does not, so that F is absolutely discriminatory. We then present two potential applications: a Stern–Gerlach-type deflector capable of spatially separating the enantiomers of a chiral molecule and a diffraction grating to which chiral molecules alone are sensitive; the resulting diffraction patterns thus encoding information about their chiral geometry.

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