Experimental determination of the vibrations and diffusion of isolated CO molecules moving parallel to a Pt(111) surface
Max-Planck-Institut für Strömungsforschung - Göttingen, Germany
Accepted: 6 April 1998
The full-width half-maxima (FWHM) of the 6 meV parallel frustrated translation mode of CO chemisorbed on Pt(111) (1.5 eV) have been measured using high-resolution helium atom scattering over the temperature range 50–200 K for four different isotopomers and the results are compared with earlier measurements on CO/Cu(001), which has a much lower adsorption energy of 0.7 eV. The FWHM is independent of the temperature and isotopomer and corresponds to a vibrational lifetime of 1.37±0.22 ps. The observed lifetime is attributed to both phononic and electronic frictional damping and is used, in conjunction with quasi-elastic helium scattering measurements, to estimate the diffusion barrier to be meV.
PACS: 68.35.Ja – Surface and interface dynamics and vibrations / 68.35.Fx – Diffusion; interface formation
© EDP Sciences, 1998