Molecular Dynamics an Neutron Scattering Stuies of Potassium Chlorie in Aqueous Solution

Neutron iffraction with isotopic substitution (NDIS) experiments were one on both natural abunance potassium an isotopically labele ⁴¹KCl heavy water solutions to characterize the solvent structuring aroun the potassium ion in water. Preliminary measurements suggeste that the literature value for the coherent neutron scattering length (2.69 fm) for ⁴¹K was significantly in error. This value was remeasure using a neutron power iffractometer an foun to be 2.40 fm. This revision increases significantly the contrast between the natural abunance K an ⁴¹K by about 30% (from 1.0 to 1.3 fm). The experimentally etermine structure factor of the potassium ion was then compare to that calculate from molecular ynamics (MD) simulations. Previous neutron scattering measurements of potassium gave a solvation number of 5.5 (see below). In this stuy, the NDIS an MD results are in goo agreement an allowe us to erive a coorination number of 6.1 for water molecules an 0.8 for chlorie ions aroun each K⁺ ion in 4 molal aqueous KCl solution.