Foundations of Astrochemistry II: Photon- and Radical-Induced Processes in Ices, Computational Approaches, and Biomolecular Chirality

In this chapter, key atomic and molecular processes shaping modern astrochemistry are examined, with a focus on the role of spectroscopy in interpreting astronomical data. Photon-induced processes – absorption, ionisation, and dissociation – are explored for their impact on the chemical evolution of interstellar environments. The chapter discusses experimental investigations utilising synchrotron radiation facilities to study the chemistry of interstellar ices, dust grains, and molecular clouds. Surface reactions on dust grains within icy mantles, including Langmuir– Hinshelwood and non-diffusive mechanisms, are highlighted as pathways for the formation of fundamental and complex organic molecules. Computational astrochemistry is introduced as a cornerstone of the field, encompassing wavefunction-based methods, density functional theory, and multiscale modelling, with applications that address complex astrochemical phenomena. Chirality is also explored, highlighting mechanisms such as circularly polarised light and spin-polarised electrons as potential drivers of biological homochirality. Emphasis is placed on interdisciplinary efforts and robust data repositories to advance astrochemistry and unravel the chemical complexity of the Universe and the origins of life.