LIBRATIONAL CONTROL OF REACTIONS IN LARGE CLUSTERS

A way to control the yield of reactions in clusters is presented and d emonstrated on the formation of the Cl-2 molecule from a photodissocia ted HCl molecule trapped on a Cl(Ar)(12) cluster using molecular dynam ics simulations. The key to the method is the large-amplitude libratio nal motion of the hydrogen atom prior to photolysis. Starting from the ground librational state practically no product is formed. However, t urning on the control mechanism by optical or thermal preexcitation of the system to the first excited librational state leads to a 70% Cl-2 product yield. (C) 1998 Elsevier Science B.V. All rights reserved.