Temperature dependence of the de Gennes narrowing in liquid rubidium

Experimental evidence for two different dynamical regimes in liquid rubidium

“…Apparently, above 420 K the rigidness of liquid rubidium decreases with a higher rate than at lower temperature. That softening of the generalised elastic modulus agrees with a reduction in generalised viscosity in this temperature range, although both experiments are monitoring different spatial correlations [9]. …”

“…The longitudinal viscosity is a measure for the diffusion of momentum parallel to the velocity of the particles and can be regarded as being sensitive to long lasting atomic-level stress correlations, in our case, on next neighbor distances. The evaluation of η l (Q) showed a step-like increase of the generalised viscosity with decreasing temperature at around 400 K [9]. In addition, MD-simulations of generalized viscosities at the structure factor maximum demonstrated a similar increase with decreasing temperature [29].…”

“…A configuration with an end energy of 7.38 meV was chosen, which provided an excellent energy resolution of 0.055 meV (FWHM). More experimental details can be found in [9,12,23]. Furthermore, inelastic experiments to follow the collective excitations at 320 K, 420 K, 500 K and 600 K have been performed and analysed [11].…”

“…However, recent studies demonstrated distinct changes in the rubidium dynamics on atomic length scales with increasing temperature from the melting point T melt = 312.65 K up to about twice the melting temperature [9][10][11][12]. The alkali metal rubidium has been studied for several decades and a lot of data, macroscopic and microscopic, are available over a wide temperature range from experiment and simulation (e.g.…”

Atomistics of self-diffusion in liquid metals

“…One is the neutron scattering evidences by Demmel et al for a dynamical crossover in liquid Rb [40], Pb [41], and Al [42] at around 1.5T m which happens to coincide Figure 5 of this paper.…”