[Studies of the interaction of hydrogen with transition metal surfaces]: Technical progress report

In the past year we carried out detailed measurements of the elastic and inelastic scattering of He from the Cu(100) surface. These measurements were in effect a detailed evaluation of the performance of our novel metastable-atom-detector (MAD), allowing us to compare our elastic scattering data with previous results of Lapujoulade and coworkers; the surface phonon dispersion along the <110> and <100> directions were derived from the inelastic scattering measurements; the former was compared with the data of the Canadian group who measured the phonon dispersion along the <110> direction only; another comparison was made with the Cu(111) surface phonon dispersion reported by the Goettingen group. Furthermore, because of one of the unique features of our detector we were the first to perform inelastic scattering measurements out of the plane of incidence (other detectors do not have the necessary degree of freedom to make such measurements). We demonstrated that the surface phonon density of states could easily be mapped by such measurements