Radiation and Surface-Driven Evolution of Prebiotic Astrophysical Ices

The emergence of life from non-living matter remains one of the most profound questions inmodern science. Addressing this challenge requires understanding the physical and chemicalpathways that connect the molecular inventory of the interstellar medium to the formation ofhabitable planetary environments. This thesis investigates the role of astrophysical ices withinthis continuum, combining laboratory astrochemistry, molecular spectroscopy, and planetaryscience to explore how simple cosmic molecules are processed, transformed, and ultimatelyincorporated into environments relevant for prebiotic chemistry.The first part of this work focuses on the evolution of volatile species from molecular clouds toprotoplanetary discs. Through infrared spectroscopic investigations of laboratory ice analogues,the structural organization of carbon monoxide and other volatile molecules was characterizedunder astrophysically relevant conditions. Particular attention was devoted to distinguishingmixed and segregated ice phases and to identifying spectroscopic signatures capable of tra-cing the thermal and chemical history of icy mantles. These studies demonstrate how themicroscopic architecture of interstellar ices influences subsequent chemical evolution, affectingthe trapping, mobility, and reactivity of molecules during star and planet formation. Whilethe macroscopic architecture of ice, whether layered or mixed, is a primary driver of chemicalevolution, the underlying template upon which these ices condense may also play a signifi-cant role. To explore this, we extended our laboratory simulations beyond inert substratesto include the use of ground meteoritic material as a proxy for innterplanetary dust particles.This allowed us to investigate the interfacial dynamics between the mineral surface and theice mantle, specifically looking for evidence of surface-mediated structural changes that occurduring the accretion. Comparative analysis reveals that while CO ice deposited on inert ZnSeat 10 K remains predominantly amorphous, the presence of a meteoritic backbone induces amulti-component infrared profile characterized by a distinct blue-shifted shoulder. We proposethat this feature arises from the high rugosity and intrinsic mineralogy of the meteorite, whichprovide specific adsorption sites that act as a physical template. These sites appear to facilitatea more ordered molecular arrangement than is typically observed on flat, inert surfaces at 10K, altering the physical architecture of ice mantles. If robustly confirmed, the nature of thecondensing surface should be considered when interpreting the high resolution spectroscopicsignatures of cold astrophysical environments. The resulting molecular inventory representsthe initial reservoir from which comets, planetesimals, and ultimately terrestrial planets inherittheir volatile content. The second part of the thesis investigates the effects of energetic proces-sing on astrophysical ice analogues. Using vacuum-ultraviolet photons, X-rays, and energeticelectrons, simple ice mixtures were subjected to irradiation conditions representative of inter-stellar and circumstellar environments. The experiments reveal how ionizing radiation initiatescomplex non-equilibrium chemistry through molecular dissociation, radical formation, and se-condary electron cascades. These processes drive the synthesis of increasingly complex organicspecies, including key prebiotic intermediates such as formaldehyde and formic acid. Such mo-lecules occupy central positions in reaction networks leading to sugars, amino acids, and othercompounds of biological relevance. The results highlight the fundamental role of radiation as auniversal driver of molecular complexity in environments where thermal chemistry alone wouldbe severely limited.The final part of the thesis extends this astrochemical perspective to planetary environments,focusing on the potential habitability of icy ocean worlds. In particular, the interaction betweensodium orthophosphate and water ice under electron irradiation was investigated as a modelfor surface processes occurring on Saturn’s moon Enceladus. Phosphorus is widely recognizedas one of the principal bottlenecks in origin-of-life scenarios because of its tendency to remaintrapped in chemically inert mineral phases. The experiments presented here demonstrate thatradiolytically generated hydrogen species can efficiently interact with phosphate-bearing mate-rials, promoting protonation reactions and potentially increasing phosphorus reactivity. Thesefindings suggest that surface irradiation may contribute to overcoming limitations in phosphorusbioavailability, thereby enhancing the prebiotic potential of icy planetary environments.Taken together, the results presented in this thesis reveal a continuous chemical threadlinking the cold molecular clouds of the interstellar medium to the emergence of potentiallyhabitable worlds. The structure of interstellar ices determines the initial conditions for molecu-lar evolution; energetic processing transforms simple species into increasingly complex organiccompounds; and planetary surface chemistry may activate essential nutrients required for the transition from chemistry to biology. By integrating laboratory experiments with astrophysicaland planetary contexts, this work contributes to a broader understanding of how molecularcomplexity develops across cosmic environments and how the fundamental ingredients of lifemay arise throughout the Universe.Ultimately, the study of cosmic ices extends beyond the characterization of frozen matterin space. It provides a framework for reconstructing the chemical history that connects stars,planets, and biology, offering insight into the universal processes that may transform simplemolecules into living systems.