Currently more than 200 molecules have been identified in the interstellar medium (ISM). From these, almost one third belong to complex organic molecules (COMs) which have been well established as an important class of molecules for astrochemistry. Many astrophysical laboratory simulation experiments have shown that COMs can be formed via interaction of ionizing radiation with analogue ices (H2O, CH3OH, CO, CO2, CH4, H2CO, NH3) at ISM relevant temperatures (5-10 K). The results of the processing of ice analogues containing carbon monoxide (CO) and methane (CH4) at 5 K with energetic electrons effectively mimicking secondary electrons liberated in the track of galactic cosmic rays once penetrating ISM ices from experiments at the W. M. Keck Laboratory in Astrochemistry will be discussed. Monitoring the ice in situ with Fourier-transform infrared (FTIR) spectroscopy, as well as with the electron impact quadrupole mass spectrometry (EI-QMS) and with a tunable photoionization source coupled to a reflectron time-of-flight mass spectrometer (PI-ReTOF-MS) allows for a thorough analysis of these ices. PI-ReTOF-MS studies revealed the facile synthesis of an array of COMs such as 1-propanol (C3H8O) and iso-butanal (C4H8O) – molecules responsible for the tastes and smells of chocolate. These isomer specific detections demonstrate the advancing of astrophysical laboratory experiments by the coupling of traditional techniques with more sensitive modern techniques, which provide a better understanding towards the reactions taking place within ices upon interaction with ionizing radiation. This information shows that ices processed at ultralow temperatures are likely a main source for the formation of complex organic molecules in the ISM involving non-equilibrium chemistry, and astrochemistry models can be greatly improved by including these types of reactions in reaction networks.

Chocolate molecules in space: Utilizing tunable vacuum ultraviolet light for isomer specific detection of complex organic molecules from astrophysical ice analogues

255th National Meeting (2018)

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