Foundations of Astrochemistry I: Observations and Ion- and Electron-Induced Processes in Ices

Astrochemistry is one of the newest but also most rapidly growing interdisciplinary fields of modern astronomy and space science. It is now recognised that space is a rich chemical environment in which more than 320 different molecular species are synthesised as part of star and planet formation, with such chemistry playing a crucial role in these formation processes. Furthermore, the evidence of this ‘universal’ chemistry is essential for unravelling the mechanisms that led to the origins of life on Earth and for assessing the likelihood of life existing elsewhere, both within our own solar system and among those thousands of exoplanets we can now detect and study. Built upon the foundations of atomic and molecular physics, astrochemistry relies on spectroscopy to observe the Universe and on collisional and radiation-induced processes to understand the evolution pathways of molecular synthesis, planet formation, and planetary atmospheres. This chapter provides an overview of the critical role atomic and molecular processes play in astrochemistry, emphasising the significance of both gas and condensed phases. The latter is particularly vital for the study of dust grains in the interstellar medium, where they frequently serve as sites for molecular synthesis. We also discuss the essential contribution of experimental research and the considerable challenges involved in replicating space environments. As we enter a new era of astronomy and space science, a comprehensive understanding of chemical processes, alongside physical phenomena, is indispensable for addressing some of the most profound questions in modern science – questions that demand an even deeper insight into atomic and molecular physics.