Precursor anion states in dissociative electron attachment to chlorophenol isomers

Author(s)

Kossoski, F. ; Varella, M. T. do N.

• Document type: Journal article
• Source: Journal of Chemical Physics; v. 145, n. 4 JUL 28 2016.
• Web of Science Citations: 4

Abstract

We report a theoretical study on low-energy (<10 eV) elastic electron scattering from chlorophenol isomers, namely, para-chlorophenol (pCP), meta-chlorophenol (mCP), and ortho-chlorophenol (oCP). The calculations were performed with the Schwinger multichannel method with pseudopotentials, and analysis of the computed integral cross sections and virtual orbitals revealed one sigma(CCl){*}, one sigma(OH){*}, and three pi{*} shape resonances. We show that electron capture into the two lower lying pi{*} orbitals initiates dissociative processes that lead to the elimination of the chloride ion, accounting for the two overlapping peaks where this fragment was observed. Despite the relatively small differences on the energetics of the pi{*} resonances, a major isomeric effect was found on their corresponding autodetachment lifetimes, which accounts for the observed increasing cross sections in the progression pCP < mCP < oCP. In particular, dissociation from the pi(1){*} anion of pCP is largely suppressed because of the unfavorable mixing with the sigma(CCl){*} state. We found the intramolecular hydrogen bond present in oCP to have the opposite effects of stabilizing the sigma(CCl){*} resonance and destabilizing the sigma(OH){*} resonance. We also suggest that the hydrogen abstraction observed in chlorophenols and phenol actually takes place by a mechanism in which the incoming electron is directly attached to the dissociative sigma(OH){*} orbital. Published by AIP Publishing. (AU)

• FAPESP's process: 15/23792-5 - Semiclassical non-adiabatic dynamics of transient anions
• Grantee: Fábris Kossoski
• Support Opportunities: Scholarships in Brazil - Post-Doctoral