NEW RESULTS ON THE REACTIVE SCATTERING OF ATOMIC FLUORINE BY MOLECULAR DEUTERIUM AT 3.2-KCAL/MOL COLLISION ENERGY

The F + D-2 --> DF(v(f),j(f)) + D reaction has been studied in a high resolution crossed molecular beam experiment. Seven time-of-flight spectra of the DF product at a collision energy of 3.2 kcal/mol (138.0 meV) are reported, covering a range of center-of-mass angles between 67 degrees and 180 degrees. The energy resolution of the time-of-flight spectra is typically 25 meV, much greater than in the earlier cross beam experiment of Y.T. Lee and coworkers [8b] at the same collision energy so that all the DF vibrational states v(f) = 1, 2, 3 and 4 are now clearly resolved. The DF(v(f) = 3) product manifests a more pronounced sideway scattering structure, and the relative differential cross sections for DF(v(f) = 4) are smaller by a factor of four than observed previously. The rotational temperatures are also significantly smaller than the previously reported values. These new results for the vibrational branching ratios are compared with quasiclassical trajectory calculations for the most recent potential hypersurfaces, and large discrepancies are apparent.