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Title: Excitation into 3p{sup 5}5p levels from the metastable levels of Ar

Abstract

Measurements of cross sections for electron-impact excitation out of the J=0 and J=2 3p{sup 5}4s metastable levels of argon into nine of the ten levels of the 3p{sup 5}5p manifold are presented in the energy range from threshold to 10 eV. A mixed target of atoms in both metastable levels was created by a hollow cathode discharge. Laser quenching was used to depopulate either one of the metastable levels, allowing separate measurements of the cross sections from each of the two metastable levels. Unlike the metastable excitation cross sections into 3p{sup 5}4p levels, the cross sections into the 3p{sup 5}5p levels are not found to be proportional to optical oscillator strengths.

Authors:
; ; ;  [1]
  1. Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)
Publication Date:
OSTI Identifier:
20982525
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.75.052707; (c) 2007 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; ATOMS; CROSS SECTIONS; ELECTRON-ATOM COLLISIONS; ELECTRONIC STRUCTURE; ELECTRONS; EXCITATION; GLOW DISCHARGES; HOLLOW CATHODES; LASER RADIATION; LASERS; METASTABLE STATES; OSCILLATOR STRENGTHS; PHOTON-ELECTRON INTERACTIONS

Citation Formats

Jung, R. O., Boffard, John B., Anderson, L. W., and Lin, Chun C. Excitation into 3p{sup 5}5p levels from the metastable levels of Ar. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.052707.
Jung, R. O., Boffard, John B., Anderson, L. W., & Lin, Chun C. Excitation into 3p{sup 5}5p levels from the metastable levels of Ar. United States. doi:10.1103/PHYSREVA.75.052707.
Jung, R. O., Boffard, John B., Anderson, L. W., and Lin, Chun C. Tue . "Excitation into 3p{sup 5}5p levels from the metastable levels of Ar". United States. doi:10.1103/PHYSREVA.75.052707.
@article{osti_20982525,
title = {Excitation into 3p{sup 5}5p levels from the metastable levels of Ar},
author = {Jung, R. O. and Boffard, John B. and Anderson, L. W. and Lin, Chun C.},
abstractNote = {Measurements of cross sections for electron-impact excitation out of the J=0 and J=2 3p{sup 5}4s metastable levels of argon into nine of the ten levels of the 3p{sup 5}5p manifold are presented in the energy range from threshold to 10 eV. A mixed target of atoms in both metastable levels was created by a hollow cathode discharge. Laser quenching was used to depopulate either one of the metastable levels, allowing separate measurements of the cross sections from each of the two metastable levels. Unlike the metastable excitation cross sections into 3p{sup 5}4p levels, the cross sections into the 3p{sup 5}5p levels are not found to be proportional to optical oscillator strengths.},
doi = {10.1103/PHYSREVA.75.052707},
journal = {Physical Review. A},
number = 5,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • In the light of recent experimental results of Jung et al. [Phys. Rev. A 75, 052707 (2007)], we have carried out relativistic distorted wave calculations for electron impact excitation of the ten higher-lying fine-structure levels of the 3p{sup 5} 5p configuration of argon from the lowest metastable states (the J=0,2 levels of the 3p{sup 5} 4s configuration). We compare our theoretical results with their experimental results and discuss the differences from the similar excitation to the 3p{sup 5} 4s levels from the same metastable states.
  • The radiative lifetimes and collisional deactivation rate constants of Ar(3p/sup 5/(/sup 2/P/sup 0//sub 1/2/)5p) and Ar(3p/sup 5/(/sup 2/P/sup 0//sub 3/2/)5p) levels with argon atoms have been measured by time resolved laser induced fluorescence combined with a pulsed discharge for preparation of populations in the Ar(4s) precursor levels. The radiative lifetimes of Ar(5p) levels are 100--140 ns, and their two-body deactivation rate constants are in the range of (1.2--5.6) x 10/sup -10/ cm/sup 3/ atom/sup -1/ s/sup -1/. About half of the two-body energy transfer is intramultiplet relaxation. Only about 20% of the Ar(5p) radiative decay is via 5p--4s transitions; themore » reminder is via transitions to the 5s and 3d states. The radiative cascading through the 5s and 3d states populates the 4p states with conservation of the inner core configuration. From the time dependence of the emission intensities from the 4p levels, the radiative lifetimes of the 5s and 3d states were estimated to be approx.50 ns.« less
  • We present experimental cross-section measurements for electron-impact excitation from the ground level and from the Xe(5p{sup 5}6s) J=2 metastable level into levels of the Xe(5p{sup 5}7p) manifold using the optical method. The magnitudes of cross sections for excitation out of the ground-state range from (65-365)x10{sup -20} cm{sup 2}. Cross sections out of the ground level are also investigated for pressures ranging from 0.1-1.0 mTorr, and show moderate dependence (particularly at high energies) on pressure due to cascades from resonant levels. Cross sections for excitation out of the metastable level have peak magnitudes that are on average more than an ordermore » of magnitude larger than their ground-state counterparts. Furthermore, cross sections out of the metastable levels into the Xe(5p{sup 5}7p) levels as a function of energy display a surprising variety of shapes which are discussed in relation to oscillator strengths. Together, the ground state and metastable cross sections measured in this work are expected to be useful for optical diagnostics of plasmas containing xenon.« less
  • The electron-impact excitation cross sections at low electron energies have been calculated using a fully relativistic R-matrix method for transitions between levels of 4p{sup 6}, 4p{sup 5}5s, and 4p{sup 5}5p configurations. To ensure the convergence of results, we have paid special attention to the factors that may affect the convergence of cross sections. For examples, we have included extensive configuration interactions in the wave-function expansion of the target states. A large enough R-matrix boundary has been taken to ensure the convergence of atomic wave functions. Contributions to cross sections from a large number of partial waves (up to J=39.5) havemore » been explicitly calculated. The final results are in good agreement with recent experimental data by Jung et al. [Phys. Rev. Lett. 94, 163202 (2005)] after shifting the position of electron energy. The relative difference is about 10% for four transitions out of the metastable levels. The results eliminated the significant discrepancies between theory and experimental work on excitation cross sections out of the metastable levels reported in the literature.« less
  • The radiative lifetimes and the collisional deactivation constants by Ne and Ar for all 6p, 6p', 7p, and 6d states of Xe, except two, were studied by single or two-photon laser induced fluorescence in the afterglow of a pulsed discharge (the prime symbol denotes the Xe/sup +/(/sup 2/P/sub 1//sub ///sub 2/) core rather than the Xe/sup +/(/sup 2/P/sub 3//sub ///sub 2/) core). The radiative lifetimes, 30--48 ns for 6p and 6p' states and 68--172 ns for 7p states, agree well with theoretical values; but, the agreement between experiment and theory is less satisfactory for the 6d states. The collisional deactivationmore » constants for Ne and Ar are similar if there is a nearby product level. However, the deactivation constants by Ar are much larger than for Ne, if there is a large energy defect for the product state. The product distributions also were measured; Ar collisions give products with larger energy defect than collisions with Ne, which tend to favor nearly isoenergetic product states. The number and type of product channels are related to the locations of crossings in the Rg--Xe potential curves and the more attractive nature of Ar--Xe* vs Ne--Xe*. There is no clear favoring between intra- and intermultiplet product states of Xe*. The radiative cascading (6p',7p)..-->..(7s or 4d)..-->..6p also was studied. in Ne and Ar« less