Simple Molecular Systems at Ultrahigh Pressure

* 非技术摘要 * 该项目探索极端条件下材料的性质-压力高达或超过300万个大气压（3兆巴），温度从低温条件到数千度。在这些极端条件下，简单的液体和气体可以转化为新材料，包括不寻常的金属，甚至超导体。这项研究将研究这些和相关的高压转换的性质，并将寻找当简单材料被压缩到非常高的密度时的全新现象。因此，这项工作将扩大我们对凝聚态物质中基本相互作用的了解，并导致新材料的创造。这些实验将利用国家的主要设施，如新的同步辐射和中子散射源。广泛的参与者将从这项工作中受益，包括高中生，本科生，研究生，博士后助理和访问调查员。就其对基础科学的重要性、对技术的潜在应用以及科学家的培训而言，这项工作处于快速发展的物理科学领域的最前沿。技术摘要 * 这项个人研究者奖将支持使用最近开发的金刚石压砧室、同步加速器X射线、中子散射、光谱学和传输探针，在压力高达300 GPa（3兆巴）以上的宽温度范围内继续研究简单分子材料的行为。实验将集中在低Z双原子系统，稀有气体，致密化合物和合金含有这些物种形成的代表性固体的转变。同步加速器X射线和中子衍射技术将用于确定氧、氮和氢的新型高压相的晶体结构，以及选定的多原子和新发现的高压化合物的晶体结构。拉曼、红外和光学光谱将在更广泛的条件下探测这些系统中的键合、相变和电子性质，包括在氢的致密导电流体相中的测量。化学计量氢化合物，掺杂氢系统，选定的笼形物，和其他分子材料的高压行为也将进行研究。高压x射线非弹性散射将用于测量压力对动态结构因子和电子结构的影响，扩展了对压缩激子和带隙的直接测量。高灵敏度的磁化率和新的电阻率方法将被用来研究这些材料的超导性到300 GPa的范围。这些研究中的每一项都将涉及对学生、博士后研究员和其他研究人员进行最先进的凝聚态技术的培训。

*** NON-TECHNICAL ABSTRACT ***This project explores the nature of materials at extreme conditions -- pressures up to and beyond 3 million atmospheres (3 megabars), and temperatures from cryogenic conditions to thousands of degrees. Under these extreme conditions, simple liquids and gases can be converted to novel materials, including unusual metals and even superconductors. This research will examine the nature of these and related high-pressure transformations and will search for altogether new phenomena when simple materials are compressed to very high densities. As such, the work will expand our knowledge of fundamental interactions in condensed matter as well as lead to the creation of new materials. The experiments will make use of major national facilities such as new synchrotron radiation and neutron scattering sources. A wide cross-section of participants will benefit from the work, including high school students, undergraduates, graduate students, postdoctoral associates, and visiting investigators. In terms of its importance to fundamental science, potential applications to technology, and the training of scientists, the work is at the forefront of a rapidly growing area of the physical sciences.*** TECHNICAL ABSTRACT *** This individual investigator award will support continued studies of the behavior of simple molecular materials at pressures up to above 300 GPa (3 megabars) over a broad range of temperatures using recently developed diamond-anvil cell, synchrotron x-ray, neutron scattering, optical spectroscopy, and transport probes. The experiments will focus on transformations in representative solids formed from low-Z diatomic systems, rare gases, and dense compounds and alloys containing these species. Synchrotron x-ray and neutron diffraction techniques will be used to identify crystal structures of novel high-pressure phases of oxygen, nitrogen, and hydrogen, as well as of selected polyatomics and newly discovered high-pressure compounds. Raman, infrared, and optical spectroscopy will probe bonding, phase transformations, and electronic properties in these systems over a broader range of conditions, including measurements in the dense conducting fluid phase of hydrogen. The high-pressure behavior of stoichiometic hydrogen compounds, doped hydrogen systems, selected clathrates, and other molecular materials will also be investigated. High-pressure x-ray inelastic scattering will be used to measure pressure effects on dynamic structure factors and electronic structure, extending direct measurements of excitons and band gaps on compression. Highly sensitive magnetic susceptibility and new resistivity methods will be used to study superconductivity in these materials to the 300-GPa range. Each of these studies will involve the training of students, post-doctoral fellows, and other researchers in state-of-the-art condensed matter techniques.