Surface reactivity of silicates at the atomic level

The interstellar medium is largely, but not entirely, empty space. In between stars and planets swarm clouds of molecules and dust grains. These are mostly composed of silicates, carbonaceous materials, and ices such as water, carbon dioxide, and ammonia. New planets, including Earth, form through the gradual accumulation of these interstellar dust grains. During this process, various reactions occur on the surfaces of the grains, shaping the chemistry of the developing planet. Many fundamental questions about these surface reactions on interstellar grains remain unanswered. This proposal aims to address some of them with a focus on interstellar silicates: (i) How do molecules form in outer space, and what is the role of silicate surfaces in promoting reactions? (ii) How was water brought to the Earth, and did silicates incorporate water during Earth`s early formation stages? (iii) How do exoplanet atmospheres form? Specifically, how does ice nucleation occur on dust silicate particles present in exoplanet atmospheres? Addressing the questions above has traditionally involved a combination of astronomical observations and sophisticated modeling techniques. So-called laboratory astrochemistry offers an alternative approach. By experimentally simulating the extreme conditions of outer space (temperatures below -170C and vacuum pressures), one can investigate reactions in a controlled environment and develop models one reaction at a time, contributing valuable insights into the more complex processes measured by astronomical instruments. Here, the boundaries of laboratory astrochemistry will be pushed by using state-of-the-art atomically resolved techniques; these will enable an unprecedented atom-by-atom understanding of the surface structure of interstellar silicates and the reactions thereby occurring. The research lies at the interface between surface physics, mineralogy, atmospheric physics, and astronomy. The selected topics, never studied at this fundamental level before, will help validate current theories on critical gas-silicate reactions in interstellar space and significantly advance our understanding of silicate surfaces.