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Type: Artigo de periódico
Title: Low-energy electron collisions with pyrrole
Author: de Oliveira, EM
Lima, MAP
Bettega, MHF
Sanchez, SD
da Costa, RF
Varella, MTD
Abstract: We report cross sections for low-energy elastic electron scattering by pyrrole, obtained with the Schwinger multichannel method implemented with pseudopotentials. Our calculations indicate pi(*) shape resonances in the B(1) and A(2) symmetries, and two sigma(*) resonances in the A(1) symmetry (the system belongs to the C(2v) point group). The present assignments of pi(*) resonances are very close to those previously reported for the isoelectronic furan molecule, in agreement with electron transmission spectra. The lowest-lying sigma(*) anion is localized on the N-H bond and provides a dissociation coordinate similar to those found in the hydroxyl groups of organic acids and alcohols. This sigma(*)(NH) resonance overlaps the higher-lying pi(*) resonance (possibly both pi(*) states) and could give rise to direct and indirect dissociation pathways, which arise from electron attachment to sigma(*) and pi(*) orbitals, respectively. The photochemistry of pyrrole and 9-H adenine is similar, in particular with respect to the photostability mechanism that allows for the dissipation of the photon energy, and we believe pyrrole would also be a suitable prototype for studies of dissociative electron attachment (DEA) to DNA bases. We point out the connection between the mechanisms of photostability and DEA since both arise from the occupation of sigma(*) and pi(*) orbitals in neutral excited states and in anion states, respectively. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3428620]
Subject: bonds (chemical)
electron attachment
electron impact dissociation
molecule-electron collisions
negative ions
organic compounds
pseudopotential methods
resonant states
Country: EUA
Editor: Amer Inst Physics
Citation: Journal Of Chemical Physics. Amer Inst Physics, v. 132, n. 20, 2010.
Rights: aberto
Identifier DOI: 10.1063/1.3428620
Date Issue: 2010
Appears in Collections:Unicamp - Artigos e Outros Documentos

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