In-situ Probing of Radiation-induced Processing of Organics in Astrophysical Ice Analogs—Novel Laser Desorption Laser Ionization Time-of-flight Mass Spectroscopic Studies

摘要: Understanding the evolution of organic molecules in ice grains interstellar medium (ISM) under cosmic rays, stellar radiation, and local electrons ions is critical to our understanding connection between ISM solar systems. Our study aimed at reaching this goal looking directly into radiation-induced processing these grains. We developed a two-color laser-desorption laser-ionization time-of-flight mass spectroscopic method (2C-MALDI-TOF), similar matrix-assisted laser desorption ionization (MALDI-TOF) spectroscopy. Results presented here with polycyclic aromatic hydrocarbon (PAH) probe embedded water-ice 5 K show for first time that hydrogenation oxygenation are primary chemical reactions occur astrophysical analogs when subjected Lyα radiation. found can over several unsaturated bonds product distribution corresponds their stabilities. Multiple efficiency be higher temperatures (100 K) compared 5 K—close temperatures. Hydroxylation shown have efficiencies or 100 K, indicating addition O atoms OH radicals pre-ionized PAHs barrierless process. These studies—the glimpses chemistry through analog studies—show once accreted onto lose PAH signatures radiation chemistry, which could one reason lack detection grains, particularly outer regions cold, dense clouds upper molecular layers protoplanetary disks.