Neutron investigation of collective excitations in liquid K-Cs alloys: Therole of the electron density

The investigation of the ion dynamics in the liquid alloy K52Cs48. which ha s the same electron density as Rb, was carried out by neutron inelastic sca ttering. Well defined collective excitations were observed up to the maximu m value of momentum transfer of the experiment. A scaling of the dispersion relation data was found to hold between K-Cs alloys, Rb and Cs. The sugges ted scaring points out the key role of the conduction electron density in t he collective dynamics of alkali metals.