scholarly journals Comment on electron-impact excitation cross section measurements for He-like xenon

2019 ◽  
Vol 97 (5) ◽  
pp. 576-578
Author(s):  
J.-C. Pain ◽  
M. Comet ◽  
C.J. Fontes
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Ion Trap ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Experimental Investigations ◽  
State University ◽  
Electron Beam Ion Trap ◽  
Penn State ◽  
Experimental Values

We discuss lower-than-predicted collisional–excitation cross sections for helium-like xenon measured at an Electron Beam Ion Trap facility. In a review paper (H. Chen and P. Beiersdorfer. Can. J. Phys. 86, 55 (2008)), the authors find a significant effect due to the Breit interaction between the free and the bound electrons in the excitation process of He-like xenon. The authors state that the agreement between the measured and calculated cross section values can only be found when the generalized Breit interaction is included in the calculations. We have performed new calculations with a multi-configuration Dirac–Fock code, as well as with the Penn State University suite of codes, and our conclusions are that the contribution of the Breit interaction is much lower than found in the calculations presented in the abovementioned article. In fact, our predictions are subsequently almost twice as large as the experimental values. We present these considerations in hopes of motivating new experimental investigations.

Electron-impact excitation cross-section measurements at EBITs from 1986 to 2006

2008 ◽  
Vol 86 (1) ◽  
pp. 55-71 ◽  
Author(s):  
H Chen ◽  
P Beiersdorfer
Keyword(s):  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Ion Trap ◽  
Spectroscopic Properties ◽  
Highly Charged Ions ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Wide Range ◽  
Charged Ions

This paper reviews the electron-impact excitation (EIE) measurements at electron beam ion trap (EBIT) facilities in the last 20~years. EIE cross sections are important atomic parameters fundamental to understanding the spectroscopic properties of ions. The properties of an EBIT make it an ideal device to measure the EIE cross section of highly charged ions. As a matter of fact, a report of EIE measurement was among the first papers published on the first EBIT ever built, EBIT-I. Since then, a wide range of measurements have been performed for K-shell and L-shell highly charged ions of Ti, V, Cr, Mn, Fe, Xe, and Ba using a combination of crystal spectrometers and solid-state X-ray detectors. In the last few years, the measurements were extended to all strong Fe L-shell lines by using a 6 × 6 pixel array microcalorimeter.PACS Nos.: 32.30.Jc, 32.30.Rj, 34.50.Fa, 32.70.Cs

A measurement of the cross section for production of He + (2 S ) ions by electron impact excitation of ground state helium ions

1966 ◽  
Vol 290 (1420) ◽  
pp. 74-93 ◽  
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Cross Sections ◽  
Absolute Magnitude ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Close Coupling ◽  
Born Cross Section ◽  
The Absolute ◽  
The Cross

A crossed beams method has been used to measure the cross section for the production of He + (2 S ) by electrons incident upon He + (1 S ) in the energy range from threshold to 750 eV. The cross section was measured in arbitrary units with an accuracy of ± 5 % and at the higher energies its energy dependence is in close agreement with that calculated by means of the plane-wave Born approximation. Consequently the cross section has been normalized to the plane-wave Born cross section at energies between 435 and 750 eV to obtain the absolute magnitude. An independent estimate of the absolute magnitude was made to with in ± 30 % using only the experimental parameters, and the absolute cross sections given by the two methods agree within the experimental uncertainties. The normalized cross section is compared with cross sections given by the close-coupling approximation and various Coulomb-Born approximations. At the lower energies the normalized cross section is considerably smaller than any of the theoretical values, but the measurements are consistent with the existence of a finite cross section at threshold if the energy spread of the electron beam is taken in to account.

Electron–ion interactions for trapped highly charged Ge ions

2006 ◽  
Vol 84 (1) ◽  
pp. 67-81 ◽  
Author(s):  
G Machtoub ◽  
J.R. Crespo López-Urrutia ◽  
X Zhang ◽  
H Tawara
Keyword(s):  
Electron Beam ◽  
Cross Sections ◽  
Ion Trap ◽  
Dielectronic Recombination ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Theoretical Simulation ◽  
X Ray ◽  
New Information ◽  
Excitation Processes

A theoretical simulation of complex K X-ray spectra including those from dielectronic recombination and excitation processes is presented for trapped highly charged germanium ions ( Geq+, q = 27–30) interacting with a dense electron beam. We carried out numerical calculations of transition rates, level energies, transition wavelengths, resonance and collision strengths, and satellite intensity factors. Analytical results related to cross sections of B- through He-like Ge ions were obtained as well. The simulated spectra, including the contribution from different charge states of Ge27+–Ge30+, show good overall agreement over a wide electron energy range with the available X-ray measurements from the Heidelberg electron beam ion trap (EBIT). We have also predicted the electron impact excitation cross-section ratios for different transitions of Ge29+ and Ge30+ ions. It should be emphasized that the present analysis can also provide new information and clues of possible temperature measurements for EBIT and other plasma diagnostics.PACS No.: 32.30.Rj

The 1 s -2 s excitation of hydrogen atoms by electron impact

1960 ◽  
Vol 258 (1293) ◽  
pp. 245-250 ◽  
Keyword(s):  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Born Approximation ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Hydrogen Atoms ◽  
Third Order ◽  
The Third ◽  
Intermediate States

The expression for the cross-section obtained from the second Born approximation by including only terms to the third order in the interaction energy is employed to calculate cross-sections for the electron impact excitation of the 2 s level of atomic hydrogen, allow­ance being made for distortion and polarization due to the 1 s , 2 s and 2 p 0.± 1 intermediate states. These cross-sections are compared with the available experimental data.

Measurement of absolute electron-impact excitation cross sections in Ar and N2 using H and H2 emissions as secondary standards

1988 ◽  
Vol 66 (4) ◽  
pp. 349-357 ◽  
Author(s):  
J. L. Forand ◽  
S. Wang ◽  
J. M. Woolsey ◽  
J. W. McConkey
Keyword(s):  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Emission Cross Section ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Dissociative Excitation ◽  
Excitation Cross Sections ◽  
Line Following ◽  
Good Agreement

A detailed description is given of a technique in which emissions from H and H2 are used to calibrate an apparatus used for electron-impact emission cross-section measurements in the wavelength range 90–130 nm. Absolute emission cross sections have been measured at 200 eV electron-impact energy for the 120 nm N I line following dissociative excitation of N2 and for the Ar and Ar+ lines at 104.8, 106.7, 92.0, and 93.8 nm respectively. Good agreement with earlier works is obtained in the case of the N I line when earlier data are renormalized to take into account the recent revision of the cross section for production of Lyman α from H2. Measurements of the 104.8 and 106.7 nm lines suggest a 40% cascade component for the latter line at energies of 200 eV and above.

Resonant electron impact excitation of highly charged Fe ions studied with a compact electron beam ion trap

2020 ◽  
Vol 49 (4) ◽  
pp. 511-514 ◽  
Author(s):  
Masashi Monobe ◽  
Hiroyuki A. Sakaue ◽  
Daiji Kato ◽  
Izumi Murakami ◽  
Hirohisa Hara ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Impact ◽  
Ion Trap ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Electron Beam Ion Trap ◽  
Resonant Electron ◽  
Fe Ions

Electron-impact excitation of W40+–W43+ ions: Cross-section and polarization

2020 ◽  
Vol 34 (26) ◽  
pp. 2050241
Author(s):  
Neelam Shukla ◽  
Rajesh Srivastava
Keyword(s):  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Matrix Theory ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Excitation Threshold ◽  
Plasma Modeling ◽  
Excitation Cross Sections ◽  
Density Matrix Theory

Electron-impact excitation of tungsten ions [Formula: see text] has been studied using the fully relativistic distorted wave (RDW) theory. The excitation cross-sections of selected electric dipole allowed transitions of these ions to be determined for the incident electron energies from the excitation threshold to 20 keV. Further, the calculated cross-section results are fitted with an analytical expression for direct applications in plasma modeling. In addition, using the density matrix theory, the linear polarization of the photons emitted from the excited tungsten ions when decay to their respective ground states is presented.

scholarly journals Corrigendum

2020 ◽  
Vol 18 (1) ◽  
pp. 75-75
Author(s):  
E Editorial
Keyword(s):  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Impact Excitation ◽  
Rate Coefficients ◽  
Electron Impact Excitation ◽  
Ordinate Axis ◽  
The Cross ◽  
Font Color ◽  
Corrected Figure

The Editor-in-Chief has been informed that in the article ?Comparisons of Quantemol and Morgan LXCat cross section sets for electron-neutral scattering and rate-coefficients: helium and water?, FACTA UNIVERSITATIS, Series Physics, Chemistry and Technology Vol. 17, No 2, 2019, pp. 145-159, DOI: https://doi.org/10.2298/FUPCT1902145M, the cross sections for electron-impact excitation of helium in Figure 1b) are wrongly presented. The values of the cross section in the ordinate axis are marked in the interval from 10-1 to 101 (in units 10-16 cm2), and should be from 10-2 to 100. We apologize for that oversight. After further discussion with the corresponding author, the Editor-in-Chief has decided to publish a corrigendum with corrected Figure 1. Link to the corrected article: https://doi.org/10.2298/FUPCT1902145M <br><br><font color="red"><b> Link to the corrected article <u><a href="http://dx.doi.org/10.2298/FUPCT1902145M">10.2298/FUPCT1902145M</a></b></u>

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