Planetary Original Diagnostics at Extreme Conditions with Raman Spectroscopy

我们掌握的关于巨行星的稀缺信息来自望远镜，它可以看到电磁辐射；太空任务，它只观测行星表面；以及计算模拟。通过这一奖学金的发展，我们将在实验室创造和研究极端条件下的行星材料。我们将第一次知道我们的太阳系是由什么组成的。钻石顶锤(DAC)是一种通用而简单的装置，在这种装置中，通过在两个钻石之间按下一个微小的样品(10^8毫升)，就可以产生高于大气压100万倍以上的压力。DAC将与电阻加热和激光加热相结合，使我们能够达到接近巨行星外层的条件。化学在这些压力下是不同的，不遵循传统上预期的路线。压力使原子之间的距离越来越近，从而导致物质性质的非凡变化。它可以将我们呼吸的空气变成美丽的暗红色晶体(氧气)，可以用氮气制造半导体聚合物，或者把花生酱变成钻石。当我们误解行星物质的性质时，我们所有的行星动力学模型都将失效。这个项目中感兴趣的主要元素将是氢和氦，它们占巨型气体行星质量的87%以上，以及水、氨和甲烷，它们是“冰行星”(海王星和天王星)的主要地幔成分。这些行星的磁场很强，是由发电机机制产生的。在木星的情况下，金属液态氢驱动偶极矩，而在天王星的情况下，它的发电机被认为是由于超离子水。这些分子流体的导电性是由行星地幔中的极端压力和温度引起的，其范围从20 Gpa和2000K到600 Gpa和7000K。该项目的目的是了解氢在行星内部的作用：预计这是一种金属流体状态。然而，尚不清楚它是否会与氦相互作用，或者是否能够穿透海王星和天王星的水、氨和甲烷层，形成新的化学结构或以流体不可穿透的液滴的形式积累。拉曼光谱是一种有效的技术，可以获得物质的物理化学性质。与钻石砧座技术相结合，它为了解行星材料存在的极端条件下的不同寻常的世界打开了一扇完美的窗户。该项目的一个新部分将是在一种名为动态钻石砧座的新装置中实现快速高温等温压缩，以避免氢、氦和水相关材料的特征-基于样品时间的反应问题。这个项目将同时利用我的技能和经验，实现拉曼光谱最现代的进步。这是一个多学科项目，具有约束力的材料，物理，行星和化学科学。FLF将使我能够在与木星行星相关的条件下对物质行为的相变进行第一次测量。天体物理界将受益于基本元素在行星条件下行为的坚实实验证明。另一方面，凝聚物质场将随着极端创造的新材料的知识而扩展，并带回环境条件。因此，这个项目需要在不同的科学分支之间建立独特的联系，即天体物理学和材料科学。这些实验将使英国走在极端条件和天体物理科学的前列。越来越多对高压科学感兴趣的研究小组将直接受益于计划(和现有)的内部高压设施、它们的未来发展以及它们对问题的适应能力。

The scarce information we have about Giant planets comes from telescopes, which see electromagnetic radiation; space missions, which observe only the planetary surface; and computational simulations. Through the development of this fellowship, we will create and study planetary materials under extreme conditions in our laboratory. For the first time, we will know what our solar system is made of. A diamond anvil cell (DAC) is a versatile and simple device, in which pressures of 1 million times above the atmospheric pressure and beyond can be generated by pressing a tiny sample between two diamonds, (10^8 ml). DACs will be coupled to resistive and laser heating, which allows us to reach conditions close to the Giant planets outer layers. Chemistry is different at these pressures and does not follow traditionally expected routes. Pressure causes extraordinary changes in the properties of matter by bringing the atoms closer and closer to each other. It can turn the air we breath into a beautiful dark red crystal (oxygen), make a semiconducting polymer out of nitrogen or transform peanut butter into diamond. When we misunderstand the nature of planetary materials, then all our models of planetary dynamics will go awry.The main elements of interest in this project will be hydrogen and helium which constitute over 87 % of Giant gas planets' mass, and water, ammonia and methane, the main mantle constituents of the "icy planets" (Neptune and Uranus). These planets have strong magnetic fields, created by dynamo mechanism. In the case of Jupiter metallic liquid hydrogen drives the dipole moment, while in the case of Uranus its dynamo is thought to be due to super-ionic water. Conductivity in these molecular fluids is induced by the extreme pressure and temperature in the planetary mantle, which ranges from 20 GPa and 2000 K to 600 GPa and 7000 K. The aim of this project is to understand the role of hydrogen within the planetary interiors: this is expected to be in a metallic fluid state. However, it is not known whether it will be interacting with helium or if it will be able to penetrate the water, ammonia and methane layers of Neptune and Uranus forming new chemical structures or accumulating as fluid impenetrable drops.Raman spectroscopy is an effective technique which gives access to the physico-chemical properties of matter. Coupled with diamond anvil cell technique it opens up a perfect window into the unusual world of extreme conditions at which planetary materials exist. A novel part of the project will be the fast high-temperature isothermal compression achieved within a novel devise called dynamic diamond anvil cell, to avoid problems of sample time-based reactions, characteristic of hydrogen, helium and water related materials. This project will implement the most modern advances of Raman spectroscopy at the same time utilising my skills and experience. This is a multidisciplinary project binding material, physical, planetary and chemical sciences. The FLF will enable me to make the first measurements of phase transformations in material behaviour at conditions relevant to Jovian planets. The astrophysics community will benefit from solid experimental proofs of the behaviour of fundamental elements in planetary conditions. The condensed matter field, on the other hand, will be extended with knowledge of the novel materials created at extreme and brought back to ambient conditions. Therefore, this project entails a unique link between different scientific branches, namely astrophysics and material sciences. These experiments would put the UK in the forefront of extreme conditions and astrophysics sciences. The expanding number of research groups interested in high-pressure science will benefit directly from the in-house, high-pressure facilities planned (and existing), their future development and their adaptability to their problems.