Influence of Gravity on Atomic Mobility in a Liquid

Abstract

Measurements of diffusion and thermodiffusion in liquids are very sensitive to convection caused for example by buoyancy. To reduce the impact of buoyancy-driven convection, benchmark experiments are performed in microgravity conditions. Here, we discuss the general influence of gravity on atomic mobility. The gravitational Peclet number and the gravitational length can be used to assess this influence. They show that the diffusion processes of atoms in a liquid is not affected by Earth’s gravitational force but that the process is dominated by the thermal energy of the atoms. Data from experiments under different gravity conditions ranging from 10^-5 g to 10^6 g are summarized. They confirm that interdiffusion is only influenced by accelerations that are orders of magnitude larger than Earth’s gravity.