title: Formation and decay of the dehydrogenated parent anion upon electron attachment to dialanine.
abstract: The dehydrogenated parent anion [M-H](-)  is one of the most dominant anions formed in dissociative electron attachment to various small biomolecules like nucleobases and single amino acids. In the present study, we investigate the [M-H](-)  channel for the dipeptide dialanine by utilizing an electron monochromator and a two-sector-field mass spectrometer. At electron energies below 2 eV, the measured high-resolution ion-efficiency curve has a different shape to that for the single amino acid alanine, which is explained by the altered threshold energies for formation of [M-H](-)  determined in quantum chemical calculations. Moreover, the structure of the formed [M-H](-)  anion is further studied by investigating the unimolecular and collision-induced decay of this anion. Trajectory calculations have been carried out to aid the interpretation of the experimentally observed fragmentation patterns.
authors.affiliation: Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck, Leopold-Franzens-Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.
authors.forename: David
authors.initials: D
authors.lastname: Gschliesser
authors.forename: Violaine
authors.initials: V
authors.lastname: Vizcaino
authors.forename: Michael
authors.initials: M
authors.lastname: Probst
authors.forename: Paul
authors.initials: P
authors.lastname: Scheier
authors.forename: Stephan
authors.initials: S
authors.lastname: Denifl
mesh_terms: D000409:Alanine / Q000737:chemistry*; D000596:Amino Acids / Q000737:chemistry*; D000838:Anions / Q000737:chemistry*; D004583:Electrons; D006865:Hydrogenation; D013058:Mass Spectrometry; D008958:Models, Molecular; D011789:Quantum Theory
chemical_list: D000596:Amino Acids; D000838:Anions; D000409:Alanine