Direct Evidence for the Translation-Rotation Coupling of HD in J>0 Bound States Resonances above the Cu(001) Surface

Physical Chemistry Chemical Physics 5, 877 (2003)

L. V. Goncharova(1), B.J Hinch(1), M. Hassel(2), A. Hellman(2), and M. Persson(2)
(1)Department of Chemistry and Laboratory of Surface Modification,Rutgers University, 610 Taylor Road, Piscataway, NJ 08854, USA
(2)Department of Applied Physics, Chalmers/Göteborg University, S-412 96 Göteborg, Sweden

Abstract

The laterally averaged HC-Cu(100) physisorption potential has been investigated in studies of rotationally mediated selective adsorption resonances. To first approximation the results are consistent with those from other isotope systems, i.e, H2 and D2 above Cu(100). The additional effects of the translational-rotational coupling, of HD, on the resonance levels have also been investigated, theoretically. The measured resonance energies are in best agreement with calculations of J = 1,2 and mJ states. The zero temperature resonance energies are considerably broader than the experimental resolution function. In addition, surface temperature variations are shown to have two prominent effects: first on the strength of the rsonance structure and, second, on resonance line widths. We attribute these effects to substrate phonon coupling with the resonantly bound HD species. Also, weak shift of all resonance levels observed on hydrogen chemisorption are accompanied by furter increases of line widths.