A high resolution crossed molecular beam investigation of the absolute cross sections and product rotational states for the reaction F+D2 (v i=0; j i=0,1)→DF(v f;j f)+D

Abstract

High resolution time of flight spectra of DF products have been measured for 12 different center‐of‐mass angles in the range θ_c.m.=114° to 180° for the reaction F+D₂→DF+D at a center‐of‐mass collision energy of E_c.m.=82.5±2.6 meV. The resolution is sufficient to clearly resolve the different final product vibrational states and to extract rotational product distributions for each of the vibrational states. Absolute reactive cross sections for the final vibrational states v_f=1, 2, 3, and 4 were determined from a careful calibration of the beam source intensities and detector sensitivity. For all final vibrational states, nearly the same large rotational surprisal values of Θ̄_R=5.3 were found. From the rotational distributions, it has also been possible to estimate opacity functions for these final v_f states via the method of Elsum and Gordon [J. Chem. Phys. 76, 3009 (1982)]. The angular distributions for different v_f states are compared to recent infinite order sudden approximation (IOSA) and classical trajectory calculations and the general trends with angle are in good agreement. The absolute values of the differential cross sections differ by as much as a factor of 10. The overall reactive cross section is smaller by about a factor of 2 than the most recent classical trajectory calculations, but the difference is barely within the large experimental errors. These new experiments provide critical data for further improving the parameters of the potential hypersurface.