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Title: Coincidence electron spectroscopy of electron-impact multiple ionization of argon

Abstract

Measurements of the partial double differential ionization cross sections of argon atoms have been made by performing coincidences between recoil ions and energy- and angle-selected slow electrons produced in 12-24 keV e{sup -}-Ar collisions. Results show that the Ar{sup 3+} ions are formed mainly by a two-step-one process via electron shake-off. These measurements have enabled determination of the shake-off probability S=0.14{+-}0.01 for L{sub 2,3} subshell, which is in good agreement with a theoretical predication. Additionally, Ar{sup 2+} and Ar{sup +} ions are found to arise respectively from the filling of L-shell vacancy by an auger transition and from the direct ionization of M-shell of the argon atom.

Authors:
;  [1]
  1. Atomic Physics Laboratory, Department of Physics, Banaras Hindu University, Varanasi-221 005 (India)
Publication Date:
OSTI Identifier:
20786320
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 72; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevA.72.062721; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ARGON; ARGON IONS; ATOMS; AUGER EFFECT; CROSS SECTIONS; ELECTRON SPECTRA; ELECTRON SPECTROSCOPY; ELECTRON-ATOM COLLISIONS; ELECTRONS; INNER-SHELL IONIZATION; KEV RANGE; L SHELL; M SHELL; PROBABILITY; RECOILS; VACANCIES

Citation Formats

Mondal, S., and Shanker, R. Coincidence electron spectroscopy of electron-impact multiple ionization of argon. United States: N. p., 2005. Web. doi:10.1103/PHYSREVA.72.0.
Mondal, S., & Shanker, R. Coincidence electron spectroscopy of electron-impact multiple ionization of argon. United States. doi:10.1103/PHYSREVA.72.0.
Mondal, S., and Shanker, R. Thu . "Coincidence electron spectroscopy of electron-impact multiple ionization of argon". United States. doi:10.1103/PHYSREVA.72.0.
@article{osti_20786320,
title = {Coincidence electron spectroscopy of electron-impact multiple ionization of argon},
author = {Mondal, S. and Shanker, R.},
abstractNote = {Measurements of the partial double differential ionization cross sections of argon atoms have been made by performing coincidences between recoil ions and energy- and angle-selected slow electrons produced in 12-24 keV e{sup -}-Ar collisions. Results show that the Ar{sup 3+} ions are formed mainly by a two-step-one process via electron shake-off. These measurements have enabled determination of the shake-off probability S=0.14{+-}0.01 for L{sub 2,3} subshell, which is in good agreement with a theoretical predication. Additionally, Ar{sup 2+} and Ar{sup +} ions are found to arise respectively from the filling of L-shell vacancy by an auger transition and from the direct ionization of M-shell of the argon atom.},
doi = {10.1103/PHYSREVA.72.0},
journal = {Physical Review. A},
number = 6,
volume = 72,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}
  • Angular correlations between the three outgoing electrons in the double ionization of argon by electron impact have been measured for the first time. Double and triple coincidence techniques are used to determine simultaneously all final electron energies and angles, and provide fourfold and fivefold differential cross sections, respectively. The angular distributions are consistent with a two-step model for the double ionization mechanism. The present results clearly show the feasibility and potentiality of ({ital e},3{ital e}) experiments.
  • No abstract prepared.
  • Doubly differential cross sections for single and multiple ionization of Ar have been measured for 500, 750, and 1000 eV electron impact. The cross sections were measured as a function of projectile energy loss and scattering angle. The energy loss range was 0-85% of the initial projectile energy and scattering angles were between {+-}22 deg. The data were put on an absolute scale by normalizing to total ionization cross sections available in the literature and found to be in good agreement with the absolute electron impact cross sections from DuBois and Rudd. For 750 eV impact, a comparison was mademore » between the present electron impact data and positron impact data obtained using the same experimental conditions. The same energy dependence and yields for single ionization were found for both electron and positron impact. On the other hand, the double- and triple-ionization yields are smaller for positron impact as compared to electron impact. Comparisons with photoionization data showed that for outer shell ionization the fractions of double and triple ionization of argon by photon impact are in quite good agreement with the present electron impact data.« less
  • An ({ital e},3{ital e}) spectrometer for the study of double ionization of magnesium by electron impact is described. With the spectrometer the angular and energy distributions of the ejected electrons can be measured over a range of incident-electron energies. The spectrometer incorporates two ejected-electron electrostatic energy analyzers and a tandem electrostatic analyzer for the scattered electrons. Up to eight detectors can be placed at the focal planes of each of the ejected analyzers. This increases the data rate by a factor of 64 over arrangements with two ejected-electron detectors. In order to reduce noise and establish the energy of themore » final state of the doubly charged residual magnesium ion, triple-coincidence electronics are used with a preprocessing circuit to reduce dead time. The first double-ionization study with the instrument was the ejection of a 2{ital p} inner valence electron by a 3.5 keV incident electron accompanied by the subsequent filling of the 2{ital p} hole and the emission of a 35 eV Auger electron. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.« less
  • The formation of multiply charged ions by electron impact in argon and krypton was studied with? mass spectrometer. The behavior of the ionization cross section as a function of electron energy was investigated for electron energies up to 600 ev. The ionization potentials in ev were determined to be as follows: Kr/sup 2+/ 38.45 combination rat 0.1, Kr/sup 3+/ 75.6 combination rat 0.5, Kr/sup 4+/ 146.6 combination rat 2, Kr/sup 5+/ 217.5 combination rat 10, Kr/sup 6+/ 350 combination rat 10 Ar/pp 2+/ 43.4 combination rat 0.3, Ar/ sup 3+/ 84.8 combination rat 0.5, Ar/sup 4+/ 150.0 combination rat 5.more » The shapes of the ionization curves near threshold were studied and discussed in terms of the threshold law for ionization. The maximum cross sections for each multiply charged ion was determined relative to that of the singly charged ion and compared to data obtained by previous investigators. (auth)« less