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Determination of the Gas-phase Acidities of Oligopeptides
Published on: June 24, 2013
Dissociative electron attachment to gas-phase glycine
S Ptasinska1, S Denifl, A Abedi
1Institut für Ionenphysik, Leopold-Franzens Universität Innsbruck, Technikerstr 25, 6020 Innsbruck, Austria.
Analytical and Bioanalytical Chemistry
|October 24, 2003
Summary
Investigating electron attachment to glycine revealed no stable parent anions. The dominant process observed was dissociative electron attachment, forming (glycine-H)- and H at 1.25 eV electron energy.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Molecular Physics
Background:
- Electron attachment studies are crucial for understanding molecular interactions and fragmentation pathways.
- Glycine, a fundamental amino acid, exhibits complex behavior under electron impact.
- Previous research on similar molecules suggests common electron attachment mechanisms involving the carboxyl group.
Purpose of the Study:
- To investigate low-energy electron attachment to gas-phase glycine.
- To identify and characterize product anions formed.
- To determine the dominant electron attachment and dissociation channels.
Main Methods:
- Utilized a high-resolution electron energy monochromator for precise electron energy control.
- Employed mass spectrometric detection to identify and quantify product anions.
- Studied electron attachment across various incident electron energies.
Main Results:
- No stable parent anion of glycine was formed upon free electron attachment.
- The largest dissociative electron attachment (DEA) cross-section, ~5x10⁻²⁰ m², was observed for the (glycine-H)⁻ + H channel at 1.25 eV.
- Formation of smaller fragment anions was observed at higher electron energies.
- Results showed good agreement with prior investigations, with the exception of the unobserved H⁻ fragment.
Conclusions:
- Low-energy electron attachment to glycine primarily leads to dissociative pathways rather than stable anion formation.
- The carboxyl group's π* orbital plays a significant role in the initial electron attachment process.
- The findings contribute to a deeper understanding of electron-molecule interactions in biologically relevant systems.
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