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High resolution time of flight spectra of DF products have been measured for 12 different center-of-mass angles in the range θc.m.=114° to 180° for the reaction F+D2→DF+D at a center-of-mass collision energy of Ec.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 vf=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 Θ̄R=5.3 were found. From the rotational distributions, it has also been possible to estimate opacity functions for these final vf states via the method of Elsum and Gordon [J. Chem. Phys. 76, 3009 (1982)]. The angular distributions for different vf 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.

Product rotationally state-resolved differential cross sections (DCS) have been determined for the DF(v f, j f) products of the F + D2 (v i = 0, j i = 0, 1, 2) reaction from the detailed analysis of high resolution crossed molecular beam experiments at the collision energies of 140, 180, and 240 meV. An increasing rotational excitation when going from the backward to the sideways and forward scattering regions is observed for all vibrational DF states, except for v f = 4. The DF products in v f = 4 scattered in the forward region (θcm = 0°−20°) are rotationally cooler than those scattered at intermediate scattering angles (θcm = 30°−100°). The experimental results are compared with quasiclassical trajectory (QCT) calculations on the ab initio potential energy surface (PES) of Stark and Werner. Good qualitative agreement is found for the observed trend of the v f, j f state-resolved DCSs. In particular, the behavior of the v f = 4 product state is well accounted for by the QCT calculation. The results are discussed in terms of the quasiclassical state-to-state reaction probabilities as a function of the total angular momentum (opacity functions).

Absolute diffraction probabilities for the scattering of D2 from a clean Cu(001) surface along the [100] azimuth have been measured at incident kinetic energies between 20 and 250 meV. The measured attenuation of the diffraction intensities with surface temperature corresponds to a surface Debye temperature of ΘD=341 K. The high-resolution angular distributions show clear evidence of rotationally inelastic diffraction (RID) peaks. The RID probability increases with incident energy and represents as much as 30% of the elastic diffraction probability at energies above Ei=200 meV. An Eikonal approximation analysis gives a value h=0.075 Å for the surface corrugation which is independent of incident energy. The rotational transition probabilities correspond to an effective value of δ=0.3 for the molecular eccentricity. The experimental results indicate that diffraction of D2 from Cu(001) can be accounted for by a hard-wall collision mechanism over the whole range of investigated energies.