The principles of the WIS method were first demonstrated in collaboration with the group of A. Stolow at the Steasie Institute for Molecular Science (Ottawa) by an experiment on separation of a bromine isotopic mixture. The Stolow’s experiment presents, probably, the first successful application of quantum wave packets to a technologically important problem. Recently, we have considerably advanced the approach by applying the powerful formalism of optimal control to the separation process. We identified a new separation mechanism that uses isotopically selective quantum interference between several wave packets excited in the same molecular potential by a specially designed train of pumping pulses. Presently, we are studying a new class of separation schemes which are based on rotational wave packets. These schemes involve alignment of a molecular isotopic mixture followed by a long-time free evolution of the aligned rotational states. Small differences in the moment of inertia of the isotopes result in distinct transient angular distributions, which may be used for separation and enrichment. Rotational WIS has certain important advantages as it can be performed in the ground electronic state by non-resonant pulsed lasers. This approach becomes even more attractive because of the new method for enhanced molecular alignment developed by us in 2001-2003.
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