Electron Energy-Loss Spectroscopy of Iron Nanoparticles in Lunar Soil using an Aberration-Corrected Scanning Transmission Electron Microscope

Introduction and Motivation: Mineral grains on the surfaces of airless planetary bodies like the Moon are subjected to continuous radiation processing from solar energetic ions and also experience micrometeorite impact events. Together these processes alter the morphology, chemistry, and microstructure of surface particles and are collectively known as space weathering [1]. The optical properties of material on airless body surfaces are altered by space weathering, making it difficult to understand the chemical composition or mineralogy of that planetary body from remote sensing data [2]. Space-weathering features were first recognized in lunar soil samples returned by the Apollo missions e.g., [3]. These features primarily develop in the outer 100 nm of mineral grains exposed to interplanetary space, making transmission electron microscopy (TEM) uniquely suited for studying this surface process [3].