Electron attachment to gas phase cysteine is investigated in a crossed electron/molecular beam experiment. The yield functions of the detected anions exhibit signatures of dissociative electron attachment (DEA), initiated by shape (5 eV) resonances. These parent anion precursor states decompose into a variety of negatively charged fragments with one of the most dominant channels being dehydrogenation, i.e., abstraction of the H radical with the excess electron remaining on the cysteine-like moiety. While this reaction is operative only within the low energy range, S⁻ and SH⁻ appear from both resonance regions. From energy considerations it is shown that formation of S⁻ below 3 eV must be associated with a conversion of cysteine into alanine. The present results demonstrate the capacity of electrons at subexcitation energies to effectively change the nature of amino acids.

Understanding the fundamental processes underlying the interaction of organometallic compounds with low energy electrons is desirable for optimizing methodologies for nanoscale applications. In this work, we couple experimental measurements with theories to investigate the interaction of gas phase copper(II) acetylacetonate, Cu(acac)₂, with low energy (<12 eV) electrons. Near 0 eV, a multipole-bound anion is likely to act as the doorway for the formation of a transitory molecular anion which then undergoes stabilization via a 90°-rotation of one of the acac units. The production of the parent anion competes with the dissociation processes, generating preferentially the acetylacetonate negative ion. Moreover, at incident electron energies above 3.5 eV, the electron driven fragmentation of Cu(acac)₂ is likely to produce atomic Cu. These results can suggest some potential strategies for the deposition of pure copper using an appropriate electron irradiation technique.

How the information obtained from the gas phase experiments can reflect the processes in solution is a crucial question for analytical chemistry, and particularly the selective host–guest recognition mechanisms which are fundamental in biology.