Theory of a two-step enantiomeric purification of racemic mixtures by optical means: The D2S2 molecule

Abstract

We present an optical ''enantio-purification switch'' that turns in two steps a racemic mixture of left-handed and right-handed chiral molecules into a pure sample containing the enantiomer of interest. The optical switch is composed of an ''enantio discriminator'' and an ''enantio converter'' acting in tandem. The method is robust, insensitive to decay processes, and does not require molecular preorientation. We demonstrate the method for the nanosecond purification of a racemate of ͑transiently chiral͒ D 2 S 2 molecules. The energies of the rovibrational states and the related dipole elements are obtained by ab initio calculations.

Selective photodestruction of chiral molecules of a specified configuration by coherent laser radiation

“…The suggested AAS scenario is based on combination of the methods of coherent control in oriented chiral molecules [8][9][10][11][12][13][14][15][16][17][18][19][20][21][25][26][27][28][29][30][31][32] and the concept of laser orientation-dependent selection of molecules developed by us earlier. 41 To clarify the idea of the method, let us consider the dynamics of the AAS on example of an abstract stable chiral molecule.…”

“…[25][26][27][28][29][30][31][32] First step in this direction has been made in Ref. 25, where authors derived a general condition for the AAS scenarios of such kind.…”

“…Soon after that, a few more specific laser-assisted AAS scenarios were proposed. [26][27][28][29][30][31][32] Their experimental realization seems, unfortunately, also difficult and no one of them has been realized so far for the following reasons.…”

Principles of enantio-selective excitation in three-wave mixing spectroscopy of chiral molecules

“…One possibility for enantio-selective population transfer is to use adiabatic following of field-dressed eigenstates [6,7,[9][10][11]. In other words, enantio-selectivity of the cyclic coupling should be reflected in the field-dressed eigenvalues.…”

“…In contrast, axially chiral molecules possess a rotational axis and therefore have only one non-vanishing component of their permanent dipole moment. However, transition dipole moments exist for all three projections such that excitation of ro-vibrational states may give rise to enantio-selectivity [9,11]. Similarly, induced dipole moments that come into play when the light is detuned far off resonance with any molecular transition may serve the same purpose [25][26][27].…”