title: Ion Distribution and Hydration Structure in the Stern Layer on Muscovite Surface.
abstract: Based on molecular dynamics simulations of eight ions (Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, and Ba2+) on muscovite mica surfaces in water, we demonstrate that experimental data on the muscovite mica surface can be rationalized through a unified picture of adsorption structures including the hydration structure, cation heights from the muscovite surface, and state stability. These simulations enable us to categorize the inner-sphere surface complex into two different species: an inner-sphere surface complex in a ditrigonal cavity (IS1) and that on top of Al (IS2). By considering the presence of the two inner-sphere surface complexes, the experimental finding that the heights of adsorbed cations from the muscovite surface are proportional to the ionic radius for K+and Cs+but inversely proportional to the ionic radius for Ca2+and Ba2+was explained. We find that Na+, Ca2+, Sr2+, and Ba2+can form both IS1 and IS2; K+, Rb+, and Cs+can form only IS1; and Mg2+can form only IS2. It is suggested that the formation of IS1 and IS2 is governed by the charge density of the ions. Among the eight ions, we also find that the hydration structure for the outer-sphere surface complexes of divalent cations differs from that of the monovalent cations by one adsorbed water molecule (i.e., a water molecule located in a ditrigonal cavity).
authors.affiliation: Department of Energy and Hydrocarbon Chemistry, Kyoto University , Kyoto 615-8510, Japan.|Environment and Resource System Engineering, Kyoto University , Kyoto 615-8540, Japan.
authors.forename: Kazuya
authors.identifier: 0000-0002-1360-2196
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Environment and Resource System Engineering, Kyoto University , Kyoto 615-8540, Japan.|Center for Engineering, Research into Artifacts (RACE), The University of Tokyo , Kashiwa, Chiba 277-8568, Japan.
authors.forename: Yunfeng
authors.identifier: 0000-0002-8832-1778
authors.initials: Y
authors.lastname: Liang
authors.affiliation: Environment and Resource System Engineering, Kyoto University , Kyoto 615-8540, Japan.
authors.forename: Sumihiko
authors.initials: S
authors.lastname: Murata
authors.affiliation: Environment and Resource System Engineering, Kyoto University , Kyoto 615-8540, Japan.|Fukada Geological Institute , Tokyo 113-0021, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Matsuoka
authors.affiliation: Japan Oil, Gas and Metals National Corporation (JOGMEC) , Chiba, Chiba 261-0025, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Takahashi
authors.affiliation: Department of Energy and Hydrocarbon Chemistry, Kyoto University , Kyoto 615-8510, Japan.
authors.forename: Naoya
authors.identifier: 0000-0002-5654-5603
authors.initials: N
authors.lastname: Nishi
authors.affiliation: Department of Energy and Hydrocarbon Chemistry, Kyoto University , Kyoto 615-8510, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Sakka