The Dynamic Structure Factor of Expanded Liquid Rubidium

By inelastic neutron scattering, the coherent dynamic structure factor S(Q, ω) of expanded liquid rubidium has been measured up to about 1700 K using the IN6 spectrometer at the Institut Laue‐Langevin, Grenoble. The scattering law S(Q,ω) has been determined for energy transfers from −3.5 to 20 meV in the momentum transfer region from 0.55 Å−1 to 2.6 Å−1. The existence of collective density excitations at short wavelength and high frequency for the expanded liquid metal is discussed and the Enskog self‐diffusion coefficient is evaluated from the experimental data.