Product magnetic defection slotted disk velocity analysis molecular beam kinetics: Li+CH3NO2, CCl4, and CH3I

Recoil velocity spectra of LiNO2, LiCl, and LiI reactively scattered from crossed thermal beams of Li and CH3NO2, CCl4, or CH3I have been measured by positioning a combination of an inhomogeneous electromagnet (to deflect aside nonreactively scattered Li atoms) and a slotted disk velocity analyzer between the beam collision zone and surface ionization detector. Transformation of these data into the center-of-mass (CM) coordinate system provides contour maps of the differential reaction cross sections. The CM product angular distributions from the three reactions are quite different: Li+CH3I favors backward scattering (i.e., a reversal in Li atom direction during the reaction) although the CM distribution is poorly resolved due to unfavorable kinematics; Li+CCl4 favors sideways scattering; and Li+CH3NO2 favors forward scattering. The product recoil energy distributions are quite similar for all three reactions and indicate potential energy surfaces with substantial repulsion between the products. These results are discussed in relation to previous work on related reactions and interpreted in terms of the electronic structure of ion-pair intermediates.