On the Formation of Complex Organic Molecules in Astrophysically-Relevant Laboratory Ices

Extraterrestrial ices, such as those found on interstellar icy grains, comets, and Kuiper Belt Objects (KBOs), serve as incubators for the formation of complex organic molecules (COMs). The accretion of common reactants like water, carbon monoxide, carbon dioxide, methanol, and ammonia into these ices along with an external source of energy such as solar wind, cosmic rays, or ultraviolet photons to process these ices can lead to a variety of COMs, some of which may have biological significance. To better understand the possible inventory of COMs and their formation mechanisms inside the ices, laboratory experiments are necessary to simulate their chemical, energetic, and temperature conditions. This presentation describes an ultrahigh vacuum machine used to simulate these conditions to monitor and isomer-selectively detect key organic molecules capable of formation inside extraterrestrial ices. By utilizing tunable laser photon energies coupled with reflectron time-of-flight mass spectrometry (ReTOF-MS), techniques such as selective photoionization (PI), resonance enhanced multiphoton ionization (REMPI), photoionization efficiency (PIE) curves, and selective photolysis, which are all supported by theoretical chemical calculations, specific isomers of COMs can be identified. These experiments demonstrate how COMs can be synthesized via non-equilibrium chemistry initiated by high energy ions and photons inside extraterrestrial ices.