Chiral molecule formation in interstellar ice analogs: alpha-aminoethanol NH2CH(CH3)OH

Aims: Aminoalcohol molecules such as alpha-aminoethanol NH₂CH(CH₃)OH may be aminoacid precursors. We attempt to characterize and detect this kind of molecules which is important to establish a possible link between interstellar molecules and life as we know it on Earth.
Methods: We use Fourier transform infrared (FTIR) spectroscopy and mass spectrometry to study the formation of alpha-aminoethanol NH₂CH(CH₃)OH in H₂O:NH₃: CH₃CHO ice mixtures. Isotopic substitution with ¹⁵NH₃ and ab-initio calculation are used to confirm the identification of alpha-aminoethanol.
Results: After investigating the thermal reaction of solid NH₃ and acetaldehyde CH₃CHO at low temperature, we find that this reaction leads to the formation of a chiral molecule, the alpha aminoethanol NH₂CH(CH₃)OH. For the first time, we report the infrared and mass spectra of this molecule. We also report on its photochemical behavior under VUV irradiation. We find that the main photo-product is acetamide (NH₂COCH₃). Data provided in this work indicates that alpha-aminoethanol is formed in one hour at 120 K and suggests that its formation in warm interstellar environments such as protostellar envelopes or cometary environments is likely.