LAUSR

We study, both classically and quantum mechanically, enantioselective orientation of gas phase chiral molecules excited by laser fields with twisted polarization. Counterintuitively, the induced orientation does not disappear after the excitation, but stays approximately constant long after the end of the laser pulses. The direction of orientation depends on both the handedness of the molecules and the sense of polarization twisting. We demonstrate the appearance of this long-lasting orientation using propylene oxide molecules (${\rm CH_{3}CHCH_{2}O}$, or PPO) as an example, and considering two kinds of fields with twisted polarization: a pair of delayed cross-polarized pulses, and an optical centrifuge. This novel chiral effect opens new avenues for detecting molecular chirality, measuring enantiomeric excess and separation of enantiomers with the help of inhomogeneous external fields.