Astrochemical Pathways to Complex Organic and Prebiotic Molecules: Experimental Perspectives for In Situ Solid-State Studies

Abstract

A deep understanding of the origin of life requires the physical, chemical, and biological study of prebiotic systems and the comprehension of the mechanisms underlying their evolutionary steps. In this context, great attention is paid to the class of interstellar molecules known as “Complex Organic Molecules” (COMs), considered as possible precursors of prebiotic species. Although COMs have already been detected in different astrophysical environments (such as interstellar clouds, protostars, and protoplanetary disks) and in comets, the physical–chemical mechanisms underlying their formation are not yet fully understood. In this framework, a unique contribution comes from laboratory experiments specifically designed to mimic the conditions found in space. We present a review of experimental studies on the formation and evolution of COMs in the solid state, i.e., within ices of astrophysical interest, devoting special attention to the in situ detection and analysis techniques commonly used in laboratory astrochemistry. We discuss their main strengths and weaknesses and provide a perspective view on novel techniques, which may help in overcoming the current experimental challenges.

Systems Astrochemistry: A New Doctrine for Experimental Studies

“…Ex situ analysis does present some challenges due to the need to remove the sample from the astrochemical chamber and secure its transportation, all the while being sure to preclude unwanted physico-chemical changes to the residue (e.g., oxidation due to contact with ambient air). A properly validated analytical methodology should thus account for these factors (Fulvio et al, 2021).…”

Formation of Complex Organic and Prebiotic Molecules in H2O:NH3:CO2 Ices at Temperatures Relevant to Hot Cores, Protostellar Envelopes, and Planet-Forming Disks

“…It is well-known that identification of molecules, particularly COMs, with infrared spectroscopy is problematic. 45 As can be seen from Table 2, different molecules can contribute to the same bands. TPD experiments give additional information and help in the identification of newly formed COMs.…”

“…However, it is not always possible to distinguish between contributions of different species. It is well-known that identification of molecules, particularly COMs, with infrared spectroscopy is problematic . As can be seen from Table , different molecules can contribute to the same bands.…”

Formation of the Simplest Amide in Molecular Clouds: Formamide (NH2CHO) and Its Derivatives in H2O-rich and CO-rich Interstellar Ice Analogs upon VUV Irradiation

“…Complex organic molecules (COMs) have been widely observed in massive molecular clouds, high-and low-mass protostars, and cometary material (see reviews by Herbst & van Dishoeck 2009;Herbst 2017;Altwegg et al 2019). Among the successfully identified O-, N-, and S-bearing COMs, some of them attract exceptional attention in the field of astrochemistry due to their potential role in the extraterrestrial origin of building blocks of life (Muñoz Caro et al 2002;Meierhenrich 2005;Nuevo et al 2008;Fulvio et al 2021;Ioppolo et al 2021). For example, formamide (NH 2 CHO) has been suggested to be an important precursor for the formation of nucleobases (e.g., adenine, uracil, thymine, cytosine, and guanine), which are found in RNA and/or DNA structures (Saladino et al 2006; Barks et al 2010;Rotelli et al 2016).…”