Titelaufnahme

In the present study we performed dissociative electron attachment (DEA) measurements with the tripeptide trialanine, C9H17N3O4, utilizing a crossed electron-molecular beam experiment with high electron energy resolution (~100 meV). Anion efficiency yields as a function of the incident electron energy are obtained for the most abundant anions up to electron energies of ~4 eV. Quantum chemical calculations are performed to determine the thermochemical thresholds for the anions observed in the measurements. There is no evidence of a molecular anion with lifetime of mass spectrometric timescales. The dehydrogenated closed shell anion (M-H)− is one of the fragment anions observed for which the calculations show that H-loss is energetically possible from carboxyl, as well as amide groups. In contrast to the dipeptide dialanine and monomer alanine the cleavage of the N-C [alpha] bond in the peptide chain is already possible by attachment of electrons at ~0 eV.