SE1051: Connecting interstellar ice chemistry to astronomical observations: Laboratory constraints for molecular astrophysics

Infrared spectroscopy with the James Webb Space Telescope (JWST) and millimeter-wave observations with the Atacama Large Millimeter/submillimeter Array (ALMA) have transformed our view of molecular complexity in star-forming regions, protoplanetary disks, and icy environments. JWST reveals the composition and evolution of interstellar ices, while ALMA traces gas-phase molecules released into warm, chemically active regions. A central challenge, however, is connecting chemistry within icy grains to the molecular inventories observed in the gas phase. Laboratory experiments that reproduce astrophysical conditions while providing molecular-level detail are essential to address this challenge and to enable astronomical observations to more reliably constrain chemical environments.We have developed CPICE (Chirped-Pulse Ice), a laboratory platform designed to bridge solid- and gas-phase astrochemistry. CPICE combines in situ FTIR spectroscopy of cryogenic ices with chirped-pulse rotational spectroscopy of molecules following their release during controlled thermal desorption. This approach enables direct comparison of condensed-phase chemistry with gas-phase products accessible to astronomical observation, while providing sensitivity to structural isomers, conformers, and minor reaction products that can be difficult to identify using conventional techniques.We will describe applications of CPICE to problems of broad relevance to observational astronomy, including energetic processing of nitrile-containing ices by vacuum ultraviolet irradiation and keV electron bombardment, simulating the effects of photons and charged particles in interstellar environments. These experiments reveal how molecular complexity evolves under different radiation fields and how abundance ratios of related species may retain information about environmental history. We will also present experiments investigating the sublimation of molecules from icy grains during controlled warm-up. Temperature-programmed desorption measurements demonstrate that sublimation can be non-equilibrium, composition dependent, and in some cases conformer selective, potentially influencing gas-phase abundances, excitation conditions, and observed spectral signatures toward protostars and disks. As JWST and ALMA continue to reveal increasingly complex molecular inventories, laboratory tools such as CPICE will be essential for translating these observations into a deeper understanding of astrochemical evolution.