Simultaneous excitation of rotations and surface phonons in the scattering of D2 from a NaF crystal

Abstract

Angular distributions and time-of-flight spectra have been measured for the scattering of n-D2 from NaF(001) along the 〈100〉 direction at energies between 30 and 90 meV. The angular distributions reveal, in addition to the elastic diffraction peaks, additional sharp peaks due to the rotational transitions 0→2,1→3, and 0→4. The relative rotational transition probabilities show an anomalous behavior which can in part be explained by a kinematic rainbow. An enhancement of rotational transitions in grazing collisions (large θi) is also observed. The time of flight spectra confirm the assignments and reveal that phonon processes also are occurring simultaneously with the rotational transitions. © 1983.