Page 163 - Academic Press Encyclopedia of Physical Science and Technology 3rd Chemical Engineering

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Encyclopedia of Physical Science and Technology EN003H-565 June 13, 2001 20:37

Coherent Control of Chemical Reactions 225

FIGURE 20 Amplitude and phase of a laser pulse optimized either to maximize or minimize the ionization of Li 2 .
[Uberna, R., Amitay, Z., Loomis, R. A., and Leone, S. R. (1999). Disc. Faraday Society 113, 385. Reproduced by
permission of the Royal Society of Chemistry.]

The entire process is repeated for many generations until a liquid crystal SLM and optimized with a GA either
convergence is achieved. to maximize or minimize the ratio of C 5 H 5 FeCOCl to
+
An experimental illustration of the GA is shown in FeCl . Convergence was achieved typically after 100 gen-
+
Fig.21.Themoleculecyclopentadienyl–iron–dicarbonyl– erations. The optimum yield ratio and the pulse shapes
chloride was irradiated with pulses of 800 nm radiation used to achieve them are shown. (A GA was simi-
that were initially 80 ns long before entering the pulse larly used in the example of Li 2 ionization illustrated in
shaper. The phases of the laser pulses were modified with Fig. 20.)

FIGURE 21 Use of the genetic algorithm to control the dissociative ionization of cyclopentadienyl–iron–dicarbonyl
chloride. Shown on the bottom are the optimized electric fields generated to either maximize or minimize the ratio of
+
C 5 H 5 FeCOCl to FeCl . [Provided by the courtesy of T. Brixner, and adapted from Assion, A., Baumert, T., Bergt,
+
M., Brixner, T., Kiefer, B., Seyfried, V., Strehler, M., and Gerber, G. (1998). Science 282, 919.]