Low-energy electron-induced dissociation in condensed-phase L-cysteine I: Desorption of anions from chemisorbed films

[摘要] Among amino acids, cysteine has been widely studied, becoming a standard for molecular self-assembly experiments, because its mercapto group (-SH) allows the formation of self-assembled monolayers (SAMs) on metal surfaces. Dissociative electron attachment (DEA) on L-cysteine SAMs is investigated utilizing a time-of-flight mass spectrometer coupled with a low-energy electron gun. The results show that electrons with kinetic energies of 3 to 15 eV attach to L-cysteine producing anionic fragments of different masses (e.g., H-, O-, OH-, S-, SH-) via dissociation of intermediate transient anions. The anion yield functions exhibited purely resonant behaviour with electron energies below 15 eV, indicating that the formation of transient anions is the predominant mechanism of production of anionic fragments from L-cysteine dissociation.

[发布机构] Department of Chemistry and Biochemistry, University of Guelph, Guelph; ON; N1G 2W1, Canada^1;Groupe en Sciences des Radiations, Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke; QC; J1H 5N4, Canada^2

[关键词] Condensed phase;Dissociative electron attachment;Electron energies;Low energy electrons;Mercapto groups;Metal surfaces;Molecular self assembly;Time-of-flight mass spectrometers