Institute for Molecules and Materials , Radboud University , Heyendaalseweg 135 , Nijmegen 6525 AJ , The Netherlands.
European Synchrotron Radiation Facility , Grenoble 38043 , France.
Langmuir. 2018 Apr 10;34(14):4241-4248. doi: 10.1021/acs.langmuir.8b00504. Epub 2018 Mar 30.
The structure of the solid-liquid interface formed by muscovite mica in contact with two divalent ionic solutions (SrCl and BaCl) is determined using in situ surface X-ray diffraction using both specular and non-specular crystal truncation rods. The 0.5 monolayer of monovalent potassium present at the surface after cleavage is replaced by approximately 0.25 monolayer of divalent ions, closely corresponding to ideal charge compensation within the Stern layer in both cases. The adsorption site of the divalent ions is determined to be in the surface ditrigonal cavities with minor out-of-plane relaxations that are consistent with their ionic radii. The divalent ions are adsorbed in a partly hydrated state (partial solvation sphere). The liquid ordering induced by the presence of the highly ordered crystalline mica is limited to the first 8-10 Å from the topmost crystalline surface layer. These results partly agree with previous studies in terms of interface composition, but there are significant differences regarding the structural details of these interfaces.
利用镜面和非镜面晶体截断棒的原位表面 X 射线衍射，确定了白云母与两种二价离子溶液（SrCl 和 BaCl）接触形成的固-液界面的结构。解理后表面存在的 0.5 单层单价钾被大约 0.25 单层的二价离子取代，这两种情况下的斯特恩层内的理想电荷补偿非常接近。二价离子的吸附位置被确定为在表面的三方锥形空腔中，存在少量的面外弛豫，这与它们的离子半径一致。二价离子以部分水合状态（部分溶剂化球）被吸附。由高度有序的结晶云母存在引起的液体有序性仅限于最顶层的结晶表面层的前 8-10 Å。这些结果在界面组成方面与以前的研究部分一致，但在这些界面的结构细节方面存在显著差异。
