Proton and Ligand Interactions at Single Crystal Mineral/ Water Interfaces Using Scanning Probe Microscopy and Optical Second Harmonic Generation

环境地球化学和生物化学计划的这一奖项得到了地球科学和化学部门以及刺激竞争研究的实验计划(EPSCoR)的支持。怀俄明大学地质和地球物理系的卡里克·M·埃格尔斯顿博士和史蒂文·R·希金斯博士将开发在矿物表面电荷测量中实现晶面特异性的方法。这项研究的目标是超越表面平均方法，获得有助于了解矿物表面反应性的信息。对于具有代表性的矿物表面，如刚玉、赤铁矿、金红石和石英，将使用原子力显微镜(AFM)和原位光学二次谐波产生(SHG)光谱测量表面电荷和电势随pH和离子介质的函数。这些测量结果将与在矿物-水界面吸附有机分子后得到的结果进行比较。感兴趣的是柠檬酸、草酸、对硝基苯甲酸、4，5-二硝基苯-1，2-二元酸和罗丹明。了解有机和生物化合物与矿物表面的反应对于在分子水平上完成复杂的地质和环境过程的表征越来越重要。目前用于矿物表面地球化学研究的方法还不够完善。在这里，将测试AFM和SHG仪器的能力，作为表征在“现实世界”样品中发现的矿物表面的手段。

This award in the Environmental Geochemistry and Biochemistry Program is supported by the Divisions of Earth Sciences and Chemistry and the Experimental Program to Stimulate Competitive Research (EPSCoR). Dr. Carrick M. Eggleston and Dr. Steven R. Higgins of the Geology and Geophysics Department, University of Wyoming, will develop methods to achieve crystal-face specificity in the measurement of mineral surface charge. The goal of the research is to move beyond a surface-average approach to information helpful to understanding mineral surface reactivity. The surface charge and potential as a function of pH and ionic media will be measured using atomic force microscopy (AFM) and in-situ optical second harmonic generation (SHG) spectroscopy for representative mineral surfaces, such as, corundum, hematite, rutile and quartz. These measurements will be compared to results obtained after the adsoprtion of organic molecules at the mineral-water interface. Of interest are citric, oxalic, p-nitrobenzoic, and 4,5-dinitrobenzene-1,2-dicarboxylic acids and rhodamine. Understanding reactions of organic and biological compounds with mineral surfaces are increasingly important to complete characterization of complex geological and environmental processes at the molecular level. The methods currently used in mineral surface geochemistry are not adequate. Here, the capabilities of AFM and SHG instrumentation will be tested as means of characterizing the surfaces of mineral surfaces found in `real world` samples.