Production of Similar Fragments from the Glycine, Alanine, and Methionine Amino Acid Molecules under Low-Energy Electron Impact

Production of the ionic fragments of the same chemical composition due to a low-energy electron impact on the glycine, alanine, and methionine amino acid molecules has been studied both experimentally and theoretically. The mass-spectrometric technique was applied to detect the above ionic fragments within the 1-720 a.m.u. mass range with the ± 0.25 a.m.u. resolution, while the density functional theory based theoretical approach allowed the relevant species to be identified and the mechanisms of their production to be clarified. A special attention has been paid to analysis of the geometrical structures of the molecules under study as well to finding the appearance potentials of their fragments with the accuracy of ±0.1 eV.