Shim Sang-Heon, Ko Byeongkwan, Sokaras Dimosthenis, Nagler Bob, Lee He Ja, Galtier Eric, Glenzer Siegfried, Granados Eduardo, Vinci Tommaso, Fiquet Guillaume, Dolinschi Jonathan, Tappan Jackie, Kulka Britany, Mao Wendy L, Morard Guillaume, Ravasio Alessandra, Gleason Arianna, Alonso-Mori Roberto
School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA.
SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, CA 94025, USA.
Sci Adv. 2023 Oct 20;9(42):eadi6153. doi: 10.1126/sciadv.adi6153.
The spin state of Fe can alter the key physical properties of silicate melts, affecting the early differentiation and the dynamic stability of the melts in the deep rocky planets. The low-spin state of Fe can increase the affinity of Fe for the melt over the solid phases and the electrical conductivity of melt at high pressures. However, the spin state of Fe has never been measured in dense silicate melts due to experimental challenges. We report detection of dominantly low-spin Fe in dynamically compressed olivine melt at 150 to 256 gigapascals and 3000 to 6000 kelvin using laser-driven shock wave compression combined with femtosecond x-ray diffraction and x-ray emission spectroscopy using an x-ray free electron laser. The observation of dominantly low-spin Fe supports gravitationally stable melt in the deep mantle and generation of a dynamo from the silicate melt portion of rocky planets.
铁的自旋态能够改变硅酸盐熔体的关键物理性质，影响岩石行星深部熔体的早期分异及动力学稳定性。铁的低自旋态可增强铁在熔体中相对于固相的亲和性以及熔体在高压下的电导率。然而，由于实验上的挑战，铁的自旋态从未在高密度硅酸盐熔体中被测量过。我们报告了利用激光驱动冲击波压缩，结合飞秒X射线衍射以及使用X射线自由电子激光的X射线发射光谱，在150至256吉帕斯卡压力和3000至6000开尔文温度下动态压缩的橄榄石熔体中检测到主要为低自旋的铁。主要为低自旋铁的观测结果支持了下地幔中重力稳定的熔体以及岩石行星硅酸盐熔体部分产生发电机效应。
