COLLISION ENERGY AND PRODUCT POLARIZATION EFFECTS IN THE CA-ASTERISK((1)D(2)-]CACL-ASTERISK(A,B)+H REACTION(HCL)

The collision energy dependence of the Ca(1D2) + HCl --> CaCl(A) + H r eaction cross-section has been measured over the low-energy range usin g the time-of-flight technique under crossed-beam conditions. The exci tation function shows a step-like functionality which seems to be of a non-classical nature. These steps could be associated with the openin g of internal transition states that become available as the total ene rgy increases. In addition beam-gas experiments have been carried out to measure the polarization of the CaCl(B) emission to the ground ele ctronic state. The collision-energy effects and the deviation from the kinematic limit of the product polarization have been also measured a nd they show a strong product rotational momentum alignment. The react ion stereodynamics are discussed with the aid of a dynamical model for kinematically constrained reactions. Finally a comparison of the pres ent (full-collision) cross-beam reaction with the van der Waals (half- collision) photoinitiated reaction is also made.