Scattering of atomic and molecular beams at metal surfaces

The principles, variable parameters and potential information underlying experiments which involve the scattering of neutral particles with thermal kinetic energies at metal surfaces are briefly outlined. A few examples for the application of ground-state particles are presented: Diffractive scattering, studies on the kinetics of adsorption and desorption as well as reactive scattering. Scattering of electronically excited particles may give rise to electron emission as is demonstrated for metastable He-atoms impinging on clean and adsorbate covered Pd surfaces. Analysis of the electron density distributions yields information on the valence electron states of the outmost layers.