Mf. Bertino et al., A COMPARATIVE-STUDY OF THE SCATTERING OF HIGHLY ENERGETIC ATOMIC AND MOLECULAR-BEAMS FROM METALLIC SURFACES, The Journal of chemical physics, 108(24), 1998, pp. 10239-10247
Time-of-flight spectra (TOF) of supersonic He and D-2 beams in the ene
rgy range 100 less than or equal to E-i less than or equal to 250 meV
have been measured after scattering from a clean Cu(001) surface at su
rface temperatures between 100 and 950 K. The TOF spectra of both: He
and D-2 exhibit broad featureless distributions over the whole range o
f incident beam energies and surface temperatures. The intensities of
the He TOF spectra are a factor of 5 to 7 higher than those of D-2 whe
n the incident beam energies are the same and below 200 meV. For the h
ighest incident beam energies E-i greater than or equal to 200 meV and
surface temperatures T-s > 700 K the difference between the He and D-
2 TOF spectra reduces to about a factor of 3. A theoretical model is e
mployed which reproduces the TOF spectra to a very good approximation.
The comparison of the best-fit parameters for He and D-2 provides val
uable information on the interaction parameters and their dependence o
n incident energy. The analysis of the energy and temperature dependen
ce of the peak intensities of the D-2 TOF spectra allows for the separ
ation of the contribution of rotational excitations in the collision m
echanism. (C) 1998 American Institute of Physics.