The primary steps of ion solvation

I will present recent experimental results that have enabled us to observe the solvation dynamics of a single Na + ion in liquid helium. A single Na + ion is created instantly at the surface of a liquid He nanodroplet and we measured in real time the gradual attachment of individual He atoms to the ion. Our results show that the first 12 He atoms bind to Na + with a constant rate of one atom per 0.75 ps. The experimental findings are in agreement with numerical simulations based on time-dependent density-functional theory. These simulations show that the first solvation shell of the Na + ion contains 12 He atoms and is formed in about 10 ps.