INITIAL-STATE LASER CONTROL OF CURVE-CROSSING REACTIONS USING THE RAYLEIGH-RITZ VARIATIONAL PROCEDURE

A new two-step procedure for laser control of photodissociation is pre sented. In the first step of the procedure, we show that control of ph otodissociation product yields can be exerted through preparation of t he initial wave function prior to application of the photodissociation field in contrast to previous laser control studies where attention h as focused on the design of the field which induces dissociation. Spec ifically, for a chosen channel from which maximum product yield is des ired and a given photodissociation field, the optimal linear combinati on of vibrational eigenstates which comprise the initial wave function is found using a straightforward variational calculation. Any photodi ssociation pulse shape and amplitude can be assumed since the Schrodin ger equation is solved directly. Application of this method to control of product yields in the photodissociation of hydrogen iodide is demo nstrated. The second step of the control procedure involves the prepar ation of the coherent superposition of discrete levels obtained from t he previous step; design of the preparatory field can be done analytic ally for two or three level systems as demonstrated here or with other well-studied iterative field design methods. (C) 1996 American Instit ute of Physics.