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Title: High Resolution Studies of Electron Attachment to Molecules

Abstract

In this paper, we survey recent progress in studies of anion formation via (dissociative) electron attachment (DEA) to simple molecules, as measured with the laser photoelectron attachment (LPA) method at high resolution. The limiting (E{yields}0) threshold behavior of the cross sections is elucidated for s-wave and p-wave attachment. Cusps at onsets for vibrational excitation (VE), due to interaction of the DEA channnel with the VE channel, are clearly detected, and vibrational Feshbach resonances just below vibrational onsets are observed for molecules with sufficiently strong long-range attraction between the electron and the molecule. From the LPA anion yields, absolute DEA cross sections (energy range typically E = 0.001-2 eV) are determined with reference to rate coefficients for thermal electron attachment at the appropriate gas temperature (normally T{sub G} = 300 K). The experimental data are compared with theoretical cross sections, calculated within the framework of an R-matrix or an Effective Range theory approach.

Authors:
; ;  [1];  [1];  [2]
  1. Fachbereich Physik, Technische Universitaet Kaiserslautern, 67653 Kaiserslautern (Germany)
  2. (United States)
Publication Date:
OSTI Identifier:
21304846
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1125; Journal Issue: 1; Conference: ICAMDATA-2008: 6. international conference on molecular data and their applications, Beijing (China), 27-31 Oct 2008; Other Information: DOI: 10.1063/1.3141697; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ANIONS; CROSS SECTIONS; DISSOCIATION ENERGY; EFFECTIVE RANGE THEORY; ELECTRON ATTACHMENT; ELECTRON COLLISIONS; ELECTRONS; EV RANGE; EXCITATION; MOLECULAR CLUSTERS; MOLECULES; P WAVES; PHOTOIONIZATION; R MATRIX; RESOLUTION; RESONANCE; S WAVES; SYMMETRY; VIBRATIONAL STATES

Citation Formats

Braun, M., Ruf, M.-W., Hotop, H., Fabrikant, I. I., and Department of Physics and Astronomy, University of Nebraska, Lincoln, NE. High Resolution Studies of Electron Attachment to Molecules. United States: N. p., 2009. Web. doi:10.1063/1.3141697.
Braun, M., Ruf, M.-W., Hotop, H., Fabrikant, I. I., & Department of Physics and Astronomy, University of Nebraska, Lincoln, NE. High Resolution Studies of Electron Attachment to Molecules. United States. doi:10.1063/1.3141697.
Braun, M., Ruf, M.-W., Hotop, H., Fabrikant, I. I., and Department of Physics and Astronomy, University of Nebraska, Lincoln, NE. 2009. "High Resolution Studies of Electron Attachment to Molecules". United States. doi:10.1063/1.3141697.
@article{osti_21304846,
title = {High Resolution Studies of Electron Attachment to Molecules},
author = {Braun, M. and Ruf, M.-W. and Hotop, H. and Fabrikant, I. I. and Department of Physics and Astronomy, University of Nebraska, Lincoln, NE},
abstractNote = {In this paper, we survey recent progress in studies of anion formation via (dissociative) electron attachment (DEA) to simple molecules, as measured with the laser photoelectron attachment (LPA) method at high resolution. The limiting (E{yields}0) threshold behavior of the cross sections is elucidated for s-wave and p-wave attachment. Cusps at onsets for vibrational excitation (VE), due to interaction of the DEA channnel with the VE channel, are clearly detected, and vibrational Feshbach resonances just below vibrational onsets are observed for molecules with sufficiently strong long-range attraction between the electron and the molecule. From the LPA anion yields, absolute DEA cross sections (energy range typically E = 0.001-2 eV) are determined with reference to rate coefficients for thermal electron attachment at the appropriate gas temperature (normally T{sub G} = 300 K). The experimental data are compared with theoretical cross sections, calculated within the framework of an R-matrix or an Effective Range theory approach.},
doi = {10.1063/1.3141697},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1125,
place = {United States},
year = 2009,
month = 5
}
  • No abstract prepared.
  • Significant changes have been observed in both the magnitude and the energy dependence of the rate of attachment of slow (approximately equal to 3 eV) electrons to bromoethane (C/sub 2/H/sub 5/Br) in either N/sub 2/ or Ar gases with increasing density of these media from 500 to 25,000 torr for N/sub 2/ and from 500 to 42,000 torr for Ar. The observed density and energy dependences of the attachment rates are discussed on the basis of two plausible reaction schemes involving either one or two states of C/sub 2/H/sub 5/Br/sup -/. On the basis of the one-state reaction scheme, determinationsmore » were made of the absolute rate of formation of C/sub 2/H/sub 5/Br/sup -/* and of the relative magnitudes of the rates for dissociation and autoionization of the metastable C/sub 2/H/sub 5/Br/sup -/* ion as a function of the mean electron energy (epsilon). On the basis of the same reaction scheme, the lifetime of C/sub 2/H/sub 5/Br/sup -/* was estimated to be greater than or equal to13 psec in the mean energy range 0.3--1 eV. Although the vertical attachment energy for the C/sub 2/H/sub 5/Br molecule is approx.0.75 eV, the present results imply that its adiabatic electron affinity is positive (>0 eV). (auth)« less
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