Thermal conductivity of Deep Earth's materials studied by combined fast pulsed laser and optical spectroscopy techniques

了解极端条件下地幔和地核物质的热导率，对于了解地球的物理和化学过程及其演化具有重要意义。地幔持续的热传输对地球磁场的存在和稳定至关重要。地球的地幔动力学取决于对流、传导和辐射的热传递速率，理解这些过程需要了解热导率的传导和辐射部分。研究人员将在与地球深部相关的极端压力和温度条件下测量热导率的传导和辐射部分。在这项工作中开发的激光技术将推进其他领域，这些领域受益于极端情况下的热导率知识，例如各种能源应用。一系列的学生，包括地区高中生，本科生，研究生和博士后助理，将受益于高质量的科学培训在卡内基，将通过参与尖端科学，将在这项工作的过程中开发提供。研究人员将通过使用泵浦探测脉冲激光技术来确定地球关键矿物在高压和高温条件下（高达150 GPa和6000 K）的热导率。为了确定晶格热导率，他们将使用时间和空间分辨光谱辐射和/或时域热反射测量样品的热通量历史。为了推断辐射热导率，研究小组将研究这些地幔矿物在紫外到红外光谱范围内的光谱。他们将应用他们以前开发的时间分辨发射和光学宽带光谱工具，包括脉冲白色激光（超连续谱）与时间分辨多通道探测器（条纹相机和增强型CCD）相结合。这些实验将在铁和富铁合金、在大体积装置中在高P-T条件下预合成的高质量地质相关样品（例如硼镁石单晶）、硅酸盐和氧化物熔体以及行星冰上进行。这些高P-T实验数据将能够直接估计地球地幔和地核热导率的辐射和传导部分。这些测量将阐明复杂的规律，这些规律支配着深层内部的导热性，并达到足够的精确度，以极大地改进现有的行星模型。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Knowledge of thermal conductivity of the Earth's mantle and core materials under extreme conditions is important for understanding the physical and chemical processes and their evolution in the Earth. Sustained heat transport through the mantle is crucial for the existence and stability of the Earth's magnetic field. The Earth's mantle dynamics depends on the rate of heat transfer by convection, conduction, and radiation, and understanding these processes requires knowledge on the conductive and radiative parts of thermal conductivity. The investigators will conduct measurements of the conductive and radiative parts of thermal conductivity at extreme conditions of pressure and temperature that are relevant for the Earth's deep interior. The laser techniques developed in this work will advance other fields, which benefit from knowledge of thermal conductivity under extremes, for example various energy applications. A range of students, including area high school students, undergraduates, graduate students, and postdoctoral associates, will benefit from high-quality scientific training at Carnegie that will be provided by participation in the cutting-edge science that will be developed in the course of this work. The investigators will determine the thermal conductivity of the Earth's key minerals under high pressure and high temperature conditions (up to 150 GPa and 6000 K) by using pump-probe pulsed laser techniques. To determine the lattice thermal conductivity, they will measure the heat flux histories across the sample using time- and spatially- resolved spectroradiometry and/or time-domain thermoreflectance. To infer the radiative thermal conductivity, the team will study the optical spectra of these mantle minerals in the ultraviolet-to-infrared spectral range. They will apply the time-resolved emission and optical broad band spectroscopy tools that they have previously developed including pulsed white laser (supercontinuum) in combination with time-resolved multichannel detectors (streak camera and intensified CCD). The experiments will be performed on Fe and Fe-rich alloys, high-quality geologically relevant samples pre-synthesized at high P-T condition in large-volume devices (e.g. single crystals of bridgmanite), silicate and oxide melts, and planetary ices. These high P-T experimental data will enable a direct estimate of the radiative and conduction parts of the thermal conductivity of the Earth's mantle and core. These measurements will elucidate complex laws which govern thermal conductivity in the deep interior and reach sufficient accuracy to critically improve existing planetary models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.