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

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.

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.

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