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Title: Absolute cross sections for dissociative electron attachment to HCN and DCN

Abstract

Absolute partial cross sections for the formation of CN{sup -} in dissociative electron attachment to HCN and DCN have been measured using a time-of-flight ion spectrometer combined with a trochoidal electron monochromator to be 940pm{sup 2} for CN{sup -}/HCN and 340pm{sup 2} for CN{sup -}/DCN at peaks of the bands due to the {sup 2{Pi}}-shape resonance. The dissociative electron attachment bands were then recorded under higher resolution, 60 meV, with a trochoidal monochromator plus quadrupole mass filter combination and found to have a nearly vertical onset at the threshold energy and to peak at 1.85 eV. Broad structure was observed on the bands, assigned to formation of vibrationally excited CN{sup -}, from which the branching ratios could be determined to be 1,0.49, and 0.22 for the formation of CN{sup -} in the v=0,1, and 2 states, respectively. The results are compared to the recent multidimensional ab initio calculations of Chourou and Orel [Phys. Rev. A 80, 032709 (2009)].

Authors:
; ;  [1]
  1. Department of Chemistry, University of Fribourg, Chemin du Musee 9, CH-1700 Fribourg (Switzerland)
Publication Date:
OSTI Identifier:
21440439
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 82; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevA.82.010701; (c) 2010 The American Physical Society
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; BRANCHING RATIO; CROSS SECTIONS; CYANIDES; DEUTERIUM COMPOUNDS; DISSOCIATION; ELECTRON ATTACHMENT; ELECTRONIC STRUCTURE; ELECTRON-MOLECULE COLLISIONS; ELECTRONS; EV RANGE; HYDROCYANIC ACID; RESONANCE; THRESHOLD ENERGY; TIME-OF-FLIGHT METHOD; VIBRATIONAL STATES; COLLISIONS; DIMENSIONLESS NUMBERS; ELECTRON COLLISIONS; ELEMENTARY PARTICLES; ENERGY; ENERGY LEVELS; ENERGY RANGE; EXCITED STATES; FERMIONS; HYDROGEN COMPOUNDS; INORGANIC ACIDS; INORGANIC COMPOUNDS; LEPTONS; MOLECULE COLLISIONS

Citation Formats

May, O., Kubala, D., and Allan, M. Absolute cross sections for dissociative electron attachment to HCN and DCN. United States: N. p., 2010. Web. doi:10.1103/PHYSREVA.82.010701.
May, O., Kubala, D., & Allan, M. Absolute cross sections for dissociative electron attachment to HCN and DCN. United States. doi:10.1103/PHYSREVA.82.010701.
May, O., Kubala, D., and Allan, M. Thu . "Absolute cross sections for dissociative electron attachment to HCN and DCN". United States. doi:10.1103/PHYSREVA.82.010701.
@article{osti_21440439,
title = {Absolute cross sections for dissociative electron attachment to HCN and DCN},
author = {May, O. and Kubala, D. and Allan, M.},
abstractNote = {Absolute partial cross sections for the formation of CN{sup -} in dissociative electron attachment to HCN and DCN have been measured using a time-of-flight ion spectrometer combined with a trochoidal electron monochromator to be 940pm{sup 2} for CN{sup -}/HCN and 340pm{sup 2} for CN{sup -}/DCN at peaks of the bands due to the {sup 2{Pi}}-shape resonance. The dissociative electron attachment bands were then recorded under higher resolution, 60 meV, with a trochoidal monochromator plus quadrupole mass filter combination and found to have a nearly vertical onset at the threshold energy and to peak at 1.85 eV. Broad structure was observed on the bands, assigned to formation of vibrationally excited CN{sup -}, from which the branching ratios could be determined to be 1,0.49, and 0.22 for the formation of CN{sup -} in the v=0,1, and 2 states, respectively. The results are compared to the recent multidimensional ab initio calculations of Chourou and Orel [Phys. Rev. A 80, 032709 (2009)].},
doi = {10.1103/PHYSREVA.82.010701},
journal = {Physical Review. A},
number = 1,
volume = 82,
place = {United States},
year = {Thu Jul 15 00:00:00 EDT 2010},
month = {Thu Jul 15 00:00:00 EDT 2010}
}
  • The nonlocal resonance model developed earlier for the description of low-energy inelastic and reactive electron-HCl collisions has been adapted to the electron-HBr collision system. The parameters of the model have been determined by fitting the eigenphase sum in the fixed-nuclei approximation to the data of an {ital ab} {ital initio} {ital R}-matrix calculation of Morgan, Burke, and collaborators. The Schwinger-Lanczos method has been employed to solve the nuclear scattering problem with a nonlocal, complex, and energy-dependent effective potential. Fully converged cross sections have been obtained on a dense grid of energies for many vibrational excitation, deexcitation, and dissociative channels inmore » both HBr and DBr. The computed cross sections are generally in good agreement with experiment as far as data are available. {copyright} {ital 1996 The American Physical Society.}« less
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  • The process of dissociative attachment of electrons to molecular hydrogen and its isotopes in the energy range at approximately 14 eV is investigated. The dissociative electron attachment cross sections for all six hydrogen isotopes are calculated over an extended range of electron energies using the local complex potential model with the excited Rydberg {sup 2}{Sigma}{sub g}{sup +} electronic state of H{sub 2}{sup -} acting as the intermediate resonant state. A significant isotope effect in theoretical electron attachment cross sections is observed, in agreement with previous predictions and experimental observations. A two-parameter analytic expression for the cross section is derived frommore » the theory that fits accurately the numerically calculated cross sections for all isotopes. Similarly, an analytic mass-scaling relation is derived from the theory that accurately reproduces the numerically calculated rate coefficients for all isotopes in the 0.1-1000 eV temperature range by using the rate coefficient for the H{sub 2} isotope only. The latter is represented by an analytic fit expression with two parameters only.« less