报告摘要：

 A molecule or larger body is chiral if it cannot be superimposed on
its mirror image (enantiomer).  Electromagnetic fields may be chiral
too, with circularly polarized light (CPL) as the paradigmatic
example.  We recently introduced a measure of the local degree of
chiral dissymmetry in electromagnetic fields suggested the existence
of modes more selective than circularly polarized plane waves in
preferentially exciting single enantiomers in certain regions of
space.  By probing induced fluorescence intensity,  we demonstrate
experimentally an 11-fold enhancement over CPL in discrimination of
the enantiomers of a biperylene derivative by precisely sculpted
electromagnetic fields.  This result, which agrees to within 15% with
theoretical predictions, establishes that optical chirality is a
fundamental and tunable property of light, with possible applications
ranging from plasmonic sensors to absolute asymmetric synthesis.

Reference:
1.       Yiqiao Tang and Adam E. Cohen, Enhanced enantioselectivity in
excitation of chiral molecules by superchiral light, Science, 332,
333, 2011;
2.       Yiqiao Tang and Adam E. Cohen, Optical chirality and its
interaction with matter, Phys. Rev. Lett., 104, 163901, 2010 (cover
story);
3.       Yiqiao Tang, Timothy A. Cook and Adam E. Cohen, Limits on
fluorescence dtected circular dichroism of single helicene molecules,
J. Phys. Chem. A, 113, 6213, 2009;
4.       Nan Yang, Yiqiao Tang and Adam E. Cohen, Spectroscopy in
sculpted fields, Nano Today, 4, 269, 2009.