Ethanolamine ices: Experiments in simulated space conditions

¹ Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo, Trento, Italy
² Italian Space Agency (ASI), Viale del Politecnico snc, 00133 Rome, Italy
³ Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Florence, Italy
⁴ INAF – Astrophysical Observatory of Arcetri, Largo E. Fermi 5, 50125 Florence, Italy
⁵ Centro de Astrobiologia (CAB, INTA-CSIC), 28850 Madrid, Spain

^⋆ Corresponding authors; john.brucato@inaf.it; sole.biancalani@unitn.it

Received: 18 March 2024
Accepted: 16 September 2024

Abstract

Context. Laboratory experiments on the interactions between complex organic molecules, interstellar dust, and ultraviolet (UV) radiation are crucial to understanding the physicochemical mechanisms that lead to the synthesis of the observed interstellar complex organic molecules (iCOMs), and to search for new molecular species not yet observed in the gas phase of the interstellar medium (ISM).

Aims. We aim to study the role of a new, recently discovered interstellar molecule, ethanolamine (EtA, NH₂CH₂CH₂OH), in surface chemistry in the ISM.

Methods. In the laboratory, thanks to a combination of temperature programmed desorption (TPD) experiments and electron ionization (EI) mass spectrometry analyses, we studied the thermal desorption of pure ethanolamine and its mixture with water from nanometric amorphous olivine grains cooled down to 10 K, with or without UV irradiation.

Results. Ethanolamine was found to be stable, even in the presence of water, when irradiated with UV light. The presence of olivine grains strongly modified the TPD curves, trapping the molecule up to about 295 K, meaning that the precursors of some biological molecules could be retained on the grains even in the innermost parts of protoplanetary disk. We then identified a series of products formed when the molecule was irradiated onto the dust substrate.

Conclusions. Of particular interest is the fact that irradiation of ice containing ethanolamine, a molecule known to be present in the ISM, can produce more complex and astrobiologically interesting species. Furthermore, our results further our understanding of existing observational data.