Abstract
A time-of-flight method has been developed with a pulse counting technique in order to measure the velocity distribution of alkali atoms scattered from the solid surface. Time-of-flight spectra of potassium atoms scattered from the cleaved surfaces of LiF and graphite are observed and compared with theoretical curves which are calculated on the assumption of the Maxwellian distribution of velocities. All the spectra agree quite well with the Maxwellian distributions characteristic of the surface temperatures. Similar experiments performed with velocity-sel cted incidentbeams show essentially no difference in results in the energy range of 0.08 to 0.15 eV. From the present result, it is concluded that the cosine distribution observed in our previous experiments is due to the complete accommodation of potassium atoms with the surfaces.
