Quantum mechanical and quasiclassical trajectory study of state-to-state differential cross sections for the F + D_2 -> DF + D reaction in the center-of-mass and laboratory frames

摘要

Quantum mechanical (QM) and quasiclassical (QCT) state-resolved integral and differential cross sections for the DF(#upsilon#',j') products of the F + D_2(#upsilon# = 0,j = 0, 1, 2) reaction have been calculated on the ab initio potential energy surface of Stark and Werner at five collision energies in the range 34.5-240 meV with the twofold purpose of comparing extensively the QM and QCT dynamics of this reaction and of rationalizing the results of high resolution crossed molecular beam experiments performed by Toennies and co-workers (Gottingen) and by Lee and co-workers (Berkeley). The comparison with experiment is carried out not only in the center-of-mass but also in the laboratory frame, involving the simulation of experimental laboratory angular distributions and time-of-flight spectra. An overall agreement is found between theory and experiment for the rovibrationally state-resolved integral and differential cross sections. In particular, both theoretical calculations confirm the experimental observation of a significant increase of product rotational excitation for all DF vibrational states on going from backward to sideways and forward scattering regions, with the only exception of the forward scattered DF products in #upsilon#' = 4, which are rotationally cooler than those scattered at intermediate scattering angles. However, significant discrepancies remain between the theoretical results and those of the crossed beam experiments, suggesting that the full understanding of the dynamics of this prototypic reaction is still a challenge.