In situ measurements of the radiation stability of amino acids at 15–140 K

We present new kinetics data on the radiolytic destruction of amino acids measured in situ with infrared spectroscopy. Samples were irradiated at 15, 100, and 140 K with 0.8-MeV protons, and amino-acid decay was followed at each temperature with and without H2O present. Observed radiation products included CO2 and amines, consistent with amino-acid decarboxylation. The half-lives of glycine, alanine, and phenylalanine were estimated for various extraterrestrial environments. Infrared spectral changes demonstrated the conversion from the non-zwitterion structure NH2CH2(R)COOH at 15 K to the zwitterion structure +NH3CH2(R)COO− at 140 K for each amino acid studied.

► We present new kinetics data on the radiolytic destruction of amino acids at 15, 100, and 140 K. ► The amino acids glycine, alanine, and phenylalanine were studied. ► Destruction of amino acids was measured in situ with infrared spectroscopy. ► The half-lives of amino acids were estimated for various extraterrestrial environments.