Pump-dump control chirality

In Sect. 6.3, we first provide the pulse-design scheme to induce and control 7T-electron rotation in a chiral aromatic molecule. Next, on the basis of dynamical simulations in a semiempirical model, we demonstrate that the initial direction of 7T-electron rotation depends on the spatial configuration of each enantiomer with respect to the polarization direction of a linearly polarized laser pulse and then 7T electrons continue to rotate clockwise and counterclockwise (or counterclockwise and clockwise) in turn. Moreover, a pump-dump control scheme to prevent the switching of the rotation direction and realize a consecutive unidirectional JT-electron rotation is presented. 

Fig. 8.17 Sample computation of control in the pump-dump scenario for controlling chirality. Populations shown are defined in the upper right-hand comer of the figure. For example, Pg<>R denotes the population of IgO ), etc. (From Fig. 4, Ref. [264].)...

In this section, a pulse-design scheme to induce and control jt-electron rotation in a chiral aromatic molecule is provided within a frozen-nuclei approximation. We perform electron WP simulations and show that the initial direction of rr-electron rotation in a chiral aromatic molecule depends on the polarization direction of a linearly polarized laser pulse. A pump-dump method for performing unidirectional rotation of n electrons is also presented [15]. An ansa (planar-chiral) aromatic molecule with a six-membered ring, 2,5-dichloro[n](3,6)pyrazinophane (DCPH Fig. 6.1), was chosen. 

We consider a BAB molecule irradiated by two pulses, termed the pump and dump pulses. These pulses are assumed to be temporally separated by a time delay Our aim is to control the probabilities to yield of two products Pq n E), with q labeling either the right (q = D) or left (q = L) handed product. The application of this scenario to the chiral synthesis case is depicted schematically in Fig. 2. 

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