Processing of astrophysical ices by soft X-rays and swift ions

Abstract

The employment of soft X-rays and swift ions has been used in laboratory to simulate the physicochemical processing of astrophysical ice analogs by energetic photons and cosmic rays. This processing includes excitation, ionization and molecular dissociation, desorption, as well as triggers the formation of new compounds. Here we present some results from experiments employing infrared spectroscopy in two different laboratories: LNLS/CNPEM in Campinas/Brazil and GANIL/CIRIL/CIMAP in Caen/France. Among the results are the formation of alkenes and aromatic compounds during the irradiation of saturated hydrocarbon-containing ices by cosmic ray analogs, the production of the nucleobase adenine during soft X-ray photolysis of N2:CH4 ice, as well as the formation of peptide bonds during the bombardment of frozen glycine by cosmic ray analogs. The interaction between cosmic ray analogs and ionizing soft X-rays probed in the laboratory allows us to identify reaction routes that lead to chemistry enhancement of astrophysical ices and help us put constrains in prebiotic chemistry.

Photochemistry and desorption induced by X-rays in water rich astrophysical ice analogs: implications for the moon Enceladus and other frozen space environments

“…Additionally, in spite of the current datasets be representative and are in good agreement with previous experiments on irradiating of astrophysical ice analogs by strong ionizing radiation, 10,16,[23][24][25][29][30][31][32]46,49,50 additional experiments increasing the dataset at larger uences help to decrease uncertainties in the determination of F E . Future experiment may also investigate different temperatures and radiation ux to extend the current work and better clarify the chemical equilibrium scenario, an important stage for ices irradiated at astrophysical environments.…”

“…A comparison between the results of radiochemistry (ion and electron bombardment) and X-ray induced photochemistry (Xray irradiation) of astrophysical ice analogs presents lots of similarities indicating that both penetrating and ionizing agents can change considerably the chemistry of frozen species in space. 22,31,43,50 Adapted from Pilling and Bergantini 10 and Gueymard 59 and considering r À2 law Triton orbit ($30 AU) 9 Â 10 6 7.0 Â 10 3 1.1 Â 10 4…”

Photolysis of CH3CN Ices by Soft X-rays: Implications for the Chemistry of Astrophysical Ices at the Surroundings of X-ray Sources

“…Processing of astrophysical ice analogs by X-rays is a key question in understanding molecular formation, abundances, and desorption in interstellar medium and other space environments. Several experiments on X-ray irradiation showed how X-rays promote chemical evolution of astrophysical ices. − Experiments on X-ray irradiation of astrophysical ice analogs have also shown: the possible formation of S 2 on comets by X-ray irradiation of H 2 S and CH 3 CN formation by X-ray processing of water-rich astrophysical ice analogs (H 2 O/CO/NH 3 ) . The present study is one more step in understanding how X-rays affect chemical evolution of astrophysical ices not only in star forming regions but also in regions close to compact objects.…”

Sulfur Ice Astrochemistry: A Review of Laboratory Studies

“…Given that radiolysis induced by X-ray absorption can occur in interstellar and circumstellar environments, such as near T-Tauri phase stars (Gullikson and Henke 1989;Pilling and Bergantini 2015;Pilling 2017), there is also some scope for recording the X-ray absorbance spectra of astrophysical ice analogues. X-ray absorption studies have been carried out in the past in order to determine the speciation of sulfur in coal and petroleum (Spiro et al 1984;George and Gorbaty 1989;Huffmann et al 1991;Waldo et al 1991), soils (Morra et al 1997;Xia et al 1999), microbial biochemical products (Pickering et al 1998(Pickering et al , 2001Prange et al 2002), and batteries (Cuisinier et al 2013;Pascal et al 2014).…”