Extraterrestrial prebiotic molecules: photochemistryvs.radiation chemistry of interstellar ices

Abstract

Photochemistry and radiation chemistry of interstellar ices lead to the synthesis of prebiotic molecules which may be delivered to planets by meteorites and/or comets.

Extra‐Terrestrial Gas‐Phase Stereoinversion in Amino Acid Leucine: Thermal and Photochemical Channels

“…As evident from figure, there is a transfer of electron density from the lone pair of electrons on the carbonyl oxygen to the anti‐bonding orbitals of carbonyl double bond, corresponding to n →π* transition which involves an excitation energy of 234 nm corresponding to the UV region. As already introduced, the UV radiations are known to be the main source for chemical processing on interstellar ices for the formation of complex organic molecules …”

“…Though meteoritic samples analyzed contain diverse range of amino acids, however, the actual detection of even the simplest amino acid in the ISM has remained elusive so far . A number of laboratory studies have been performed to synthesize amino acids and other complex prebiotic molecular species under conditions akin to interstellar ice analogues.…”

“…Notably, several experimental and theoretical studies, have indicated that the chemical processing on the surface and even in the bulk of cosmic ices is mainly induced by ultraviolet (UV) radiations. In fact, at low temperatures of interstellar ices, UV photons are known to initiate the production of crucial intermediates which can act as precursors for complex molecules in subsequent stages of cosmic cycles . Moreover, laboratory studies mimicking the conditions of ISM, had reported the synthesis of proteinecious amino acids in ‘Urey‐Miller’ type experiments based on ‘Strecker’ reaction .…”

Nonadiabatic dynamics in multidimensional complex potential energy surfaces

“…From all the above-mentioned processes that can be formulated in terms of a complex-valued Hamiltonian, we have chosen to survey a DEA reaction as the rst application of our proposed methodology. DEA is known to play important roles, to a greater or lesser degree, in DNA damage induced by ionizing radiation, 32,33 in the action of radiosensitizing drugs, 33,34 in the chemical evolution of interstellar media 35 and planetary atmospheres, 36,37 in plasma technologies, 38 among many other examples. 19,39 Of particular relevance herein, low energy electrons can very efficiently promote DEA reactions in halogen-containing unsaturated compounds.…”

Photochemistry vs. radiation chemistry of cosmic ice analogs

“…The energetic processing of ices surrounding interstellar dust grains can be broadly categorized as either radiation chemistry or photochemistry (Arumainayagam et al 2019). Radiation chemistry involves ionizing radiation, which, in cosmic chemistry, includes high-energy particles (e.g., cosmic rays consisting mostly of protons) and high-energy photons (e.g., extreme-UV (12.4-124 eV), X-rays, and γ-rays).…”