Ultrahigh-Resolution Spin-Echo Measurement of Surface Potential Energy Landscapes
Andrew P. Jardine,*
Shechar Dworski,
Peter Fouquet,
Gil Alexandrowicz,
David J. Riley,
Gabriel Y. H. Lee,
John Ellis,
William Allison
We demonstrate two approaches that use the recently developed
helium spin-echo technique to measure surface potential energy
landscapes. For helium–lithium fluoride (100), we use
the selective adsorption phenomenon to obtain the complete experimental
band structure of atoms in a corrugated surface potential. For
carbon monoxide–copper (001), we measure the diffusion-induced
energy broadening in the scattered helium beam and extract properties
of the adsorbate-substrate potential. The measurements are made
possible by the resolution of our new spectrometer, which improves
on existing resolution by three orders of magnitude. We show
that it is possible to produce benchmark energy landscapes to
assist evaluation and development of first-principles theory
in the problematic van der Waals/weak chemisorption regime.
Present address: Institut Laue Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France.
* To whom correspondence should be addressed. E-mail: apj24{at}cam.ac.uk
