Adsorption, Diffusion and Structure Formation of Water on Calcite: Fundamental Processes in Wetting of an Omnipresent Mineral Surface

水在方解石上的吸附、扩散和结构形成：无所不在的矿物表面润湿的基本过程

• 批准号: 394742005
• 负责人: Professorin Dr. Angelika Kühnle
• 金额: --
• 依托单位: Department of Applied Physics
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/394742005?language=en
• 关键词: Adsorption; Diffusion; Structure; Formation; Water

Water at surfaces is omnipresent both in nature and technology. Therefore, solid-water interfaces are pivotal in a broad range of fields, including, e.g., geochemistry, environmental chemistry as well as catalysis. Ice nucleation at surfaces is a particularly interesting phenomenon in this context, which has been studied since centuries. Yet, many fundamental questions regarding the physico-chemical mechanisms responsible for water adsorption and structure formation at surfaces remain poorly understood.Calcite is a particularly interesting substrate to study water nucleation phenomena, since it represents the most abundant carbonate on earth. It plays a major role in many every day's life and industrial processes, including such diverse fields as scale inhibition, oil recovery, or construction. Despite the importance of the calcite-water interface, very little is known about the molecular-scale details of water adsorption, diffusion and structure formation on this surface. This lack of information is mostly due to the fact that calcite, being an electrically insulating material, represents a major challenge for classical surface science techniques. In this respect, dynamic atomic force microscopy carried out in ultra-high vacuum has proven to constitute an ideally suited technique to obtain atomic resolution on bulk insulator surfaces.The goal of the project is unravelling fundamental steps in water adsorption, diffusion and structure formation on the natural cleavage plane of calcite, namely calcite (10.4), kept in ultra-high vacuum. We will determine basic parameters in water adsorption such as free energy and entropy of adsorption as well as water monomer diffusion barriers. To elucidate temperature-dependent water structure formation, we will study water cluster formation and diffusion as well as temperature-dependent mono- and multilayer growth. Experiments with both light (H2O) and heavy (D2O) water are planned to shed light onto the influence of hydrogen bonding in these structures.In summary, the project aims at elucidating the basic physical mechanisms in water adsorption, diffusion as well as structure formation and growth on calcite (10.4) by recording AFM data at low and variable temperatures. These insights are expected to provide important fundamental input for understanding the reactivity of water-calcite interfaces in a broad range of different areas.

表面的水在自然界和技术中都无处不在。因此，固体-水界面在广泛的领域中是关键的，包括，例如，地球化学、环境化学以及催化。在这种情况下，表面的冰成核是一个特别有趣的现象，几个世纪以来一直在研究。然而，许多基本问题的物理化学机制，负责水的吸附和结构形成的表面仍然知之甚少。方解石是一个特别有趣的基板，研究水的成核现象，因为它代表了地球上最丰富的碳酸盐。它在许多日常生活和工业过程中发挥着重要作用，包括阻垢、采油或建筑等不同领域。尽管方解石-水界面的重要性，很少有人知道水的吸附，扩散和结构形成在这个表面上的分子尺度的细节。这种信息的缺乏主要是由于方解石是一种电绝缘材料，对经典的表面科学技术来说是一个重大挑战。在这方面，在超高真空中进行的动态原子力显微镜已被证明构成一个理想的合适的技术，以获得大绝缘体表面上的原子分辨率。该项目的目标是解开水的吸附，扩散和结构形成的方解石，即方解石（10.4），保持在超高真空的天然解理面的基本步骤。我们将确定水吸附的基本参数，如自由能和吸附熵以及水单体的扩散障碍。为了阐明温度依赖的水结构的形成，我们将研究水簇的形成和扩散以及温度依赖的单层和多层的生长。计划用轻水（H2O）和重水（D2 O）进行实验，以阐明氢键在这些结构中的影响。总之，该项目旨在通过记录低温和变温下的AFM数据，阐明水在方解石（10.4）上吸附、扩散以及结构形成和生长的基本物理机制。这些见解预计将提供重要的基本输入，了解水方解石界面的反应性在广泛的不同领域。