An (e,2e) study of double excitation-autoionization mechanisms in helium

McDonald, Donald G.; Crowe, A

doi:10.1088/0953-4075/26/17/021

Cited by 21 publications

(25 citation statements)

References 35 publications

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“…The shape of a single resonance is described by the Shore parameters a is represented by a linear function with coefficients c and d. The Fano shape parameter q i was obtained from the best-fit values of a i and b i , according to the method of McDonald and Crowe [28]. Strictly speaking, the formula presented in Eq.…”

Section: Resultsmentioning

confidence: 99%

Experimental studies of partial photodetachment cross sections in K−below the K(7 2P) threshold

et al. 2012

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A collinear beams apparatus has been used to determine photodetachment cross sections for K − in the photon energy range 4.250-4.360 eV. State-selective detection, utilizing a resonance ionization scheme, was applied to measure partial cross sections for those channels which leave the residual K atoms in the excited 7 2 S, 5 2 F , and 5 2 G states. The energy region studied encompassed the openings of the aforementioned channels, as well as the channel that leaves the K atom in the 7 2 P state. Two previously unobserved resonances were seen in all three partial cross sections between the K(5 2 G) and K(7 2 P ) thresholds. It is shown that a more reliable determination of resonance parameters can be made if the same resonances are observed in several channels. In the region below the K(5 2 F ) threshold, three previously observed resonances were investigated [Kiyan et al., Phys. Rev. Lett. 84, 5979 (2000)]. A greatly increased modulation of the signal was obtained by detecting in the K(7 2 S) channel instead of the K(5 2 S) channel used in the previous study. Furthermore, the shapes of the cross sections in the threshold regions are discussed. A detailed description of the apparatus and the experimental procedure employed is presented in the paper.

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Section: Resultsmentioning

confidence: 99%

Experimental studies of partial photodetachment cross sections in K−below the K(7 2P) threshold

et al. 2012

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“…Using a fitting procedure similar to that outlined by McDonald and Crowe (1993), values of q and q ⊥ were obtained. The resonant polarization function (ε = 0) was then obtained from (Defrance 1980)…”

Section: Experimental Methodsmentioning

confidence: 99%

Excitation and polarization of the 3³D state of helium by electron impact

Cvejanović¹,

Clague²,

Fursa³

et al. 2000

J. Phys. B: At. Mol. Opt. Phys.

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Electron impact excitation of the 33D state of helium has been studied experimentally and theoretically using the convergent close coupling (CCC) and R-matrix with pseudo-states (RMPS) methods. Experimental and theoretical CCC emission cross sections and polarizations of the 33D→23P line are reported. Theoretical cross sections for direct excitation of the 33D state and polarizations of corresponding emitted radiation are also reported using both CCC and RMPS methods. Particular attention has been given to making realistic estimates of the large cascade contributions to both the cross sections and the polarization fraction of the 33D→23P radiation, using the CCC approach. The self-consistency of the experimental and theoretical polarization data gives confidence in their quality. On the other hand differences remain between experimental and theoretical emission cross sections at higher energies.

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“…In addition, the 10 eV and 20 eV ejected electron data were also measured with another (e, 2e) spectrometer previously used by McDonald and Crowe (1993) to study excitationautoionization in helium. This served as a valuable check of the reproducibility of the data and also extended the angular ranges in both the binary and recoil directions.…”

Section: Experimental Apparatusmentioning

confidence: 99%

Experimental and theoretical (e, 2e) studies of argon (3p) ionization in asymmetric geometry

Stevenson¹,

Leighton²,

Crowe³

et al. 2005

J. Phys. B: At. Mol. Opt. Phys.

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Experimental and theoretical triple-differential cross sections (TDCS) are presented for ionization of the outer 3p shell of argon by 200 eV electrons scattered through an angle of 15° and for ejected electron energies of 2, 5, 10 and 20 eV. A distorted-wave Born approximation (DWBA) and a hybrid DWBA-R-matrix (DWBA-RM2) calculation both reproduce the shapes of the TDCS when the slow electron is ejected near the momentum-transfer direction. Near the opposite direction, the DWBA-RM2 model also achieves good agreement with experiment for the higher ejected electron energies, but discrepancies are observed for the lower energies. This three-way joint study emphasizes that it is essential to include a proper treatment of exchange in modelling low-energy ionization.

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An (e,2e) study of double excitation-autoionization mechanisms in helium

Cited by 21 publications

References 35 publications

Experimental studies of partial photodetachment cross sections in K−below the K(7 2P) threshold

Experimental studies of partial photodetachment cross sections in K−below the K(7 2P) threshold

Excitation and polarization of the 3³D state of helium by electron impact

Experimental and theoretical (e, 2e) studies of argon (3p) ionization in asymmetric geometry

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An (e,2e) study of double excitation-autoionization mechanisms in helium

Cited by 21 publications

References 35 publications

Experimental studies of partial photodetachment cross sections in K−below the K(7 2P) threshold

Experimental studies of partial photodetachment cross sections in K−below the K(7 2P) threshold

Excitation and polarization of the 33D state of helium by electron impact

Experimental and theoretical (e, 2e) studies of argon (3p) ionization in asymmetric geometry

Contact Info

Product

Resources

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Excitation and polarization of the 3³D state of helium by electron impact