Discriminatory optical force for chiral molecules
We suggest that the force F exerted upon a chiral molecule by light assumes the form $\mathbf {F}=a\boldsymbol {\nabla } w+b\boldsymbol {\nabla } h$ 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 op...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2014-01-01
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| Series: | New Journal of Physics |
| Online Access: | https://doi.org/10.1088/1367-2630/16/1/013020 |
| Summary: | We suggest that the force F exerted upon a chiral molecule by light assumes the form $\mathbf {F}=a\boldsymbol {\nabla } w+b\boldsymbol {\nabla } h$ 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 $\boldsymbol {\nabla }$ 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 $\boldsymbol {\nabla } w$ vanishes but $\boldsymbol {\nabla }h$ 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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| ISSN: | 1367-2630 |