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Possible dissociation pathways for formation of H ˉ (A), O ˉ (B and C), OH ˉ (D), S ˉ (E), SH ˉ (F) and COOH – /HCOOH – (G) after LEE
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We investigate electron attachment to chemisorbed and physisorbed L-cysteine/Au(111) films and its subsequent dissociation via electron stimulated desorption (ESD) measurements; More specifically, dissociative electron attachment (DEA) which in essentially, molecular dissociation into a neutral and anionic fragment following initial electron captur...
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Here we report the results of dissociative electron attachment (DEA) to gas-phase chromium(0) hexacarbonyl (Cr(CO)6) and benzene-chromium(0) tricarbonyl ((η⁶-C6H6)Cr(CO)3) in the energy range of 0-12 eV. Measurements have been performed utilizing an electron-molecular crossed beam setup. It was found that DEA to Cr(CO)6 results (under the given exp...
Dissociative electron attachment (DEA) and ion-pair dissociation (IPD) processes of Difluoromethane (CH2F2) have been studied in the incident electron energy range 0 to 45 eV. Three different fragment anions (F − , CHF − and F − 2) are detected in the DEA range and two anions (F − and CHF −) are detected in IPD range. Absolute cross-section of the...
We investigate electron attachment to large ammonia clusters doped with a single benzene (Bz) molecule (NH3)N·Bz, N̄ ≈ 320. Negatively charged clusters are probed by mass spectrometry, and the energy-dependent ion yields are derived from mass spectra measured at different electron energies. The ion efficiency curves of pure ammonia clusters exhibit...
We have measured the electron stimulated desorption (ESD) yields of anions and cations from thin films of Fe(CO)5 deposited onto both Xe or Pt surfaces. Measurements were made as functions of incident electron energy, incident current, and the thickness of both the Fe(CO)5 and Xe layers. The desorption of C? and O? occur exclusively via dipolar dis...
Citations
... Although these authors could observe the cation ESD yield from the benzene molecule adsorbed on the argon spacer layer, the low sensitivity of the experimental setup prevented the detection of any other desorbed fragments, apart from H + after benzene deposited directly on the Pt surface. Many of the main experimental contributions to ESD from biomolecules of relevant radiobiological interest such as thiophene 41 , nitromethane 42,43 , NO and N2O 44 and DNA [45][46][47] , have been performed in our laboratory at the University of Sherbrooke using the experimental set up employed in the present study. ...
The electron induced dissociation of condensed benzene (C6H6) in thin films deposited on a Pt substrate is investigated by the electron stimulated desorption (ESD) of anions and cations. The desorbed...
Cysteine is the simplest thiolated, chiral amino acid and is often used as the anchor for studies of self-assembled monolayers (SAMs) of complex biomolecules such as peptides. Understanding the interaction of SAMs of cysteine with low-energy secondary electrons (SEs) produced by X-rays can further our understanding of radiation damage in biomolecules. In particular, if the electrons are polarized, chiral-selective chemistry could have bearing on the origin of homochirality in nature. In the present paper, we use synchrotron radiation-based X-ray photoelectron spectroscopy to determine the changes that occur in the bonding of self-assembled layers of cysteine on gold as a result of soft X-ray irradiation. To investigate the possibility of chiral selectivity resulting from the interaction of low-energy, spin-polarized SEs (SPSEs), measurements were conducted on cysteine adsorbed on a 3 nm-thick gold layer deposited on a CoPt thin-film multilayer with perpendicular magnetic anisotropy. Time-dependent measurements of the C 1s, N 1s, O 1s, S 2p, and Au 4f core levels are used to follow the changes in surface chemistry and determine reaction cross-sections as a function of SE exposure. Analysis of the data results in cross-sections in the range of 5-7 Mb and suggests possible reaction pathways. Changing the magnetization direction of the CoPt multilayer produces SPSEs with opposite polarity. Some evidence of spin-dependent reactions is indicated but is inconclusive. Possible reasons for the discrepancy are posited.
