Shake theory predictions of excited-state populations following 1s ionisation in argon

Dyall, K G

doi:10.1088/0022-3700/16/17/008

Cited by 47 publications

(32 citation statements)

References 19 publications

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“…The results show that in the asymptotic limit the shakeoff channel prevails over the shakeup. This is consistent with the previous result of Armen [14] and is in contrast with the theoretical prediction by Dyall [20]. The ½1s3p shakeoff threshold energy was found at 3236:3 AE 0:7 eV and ½1s3p4p; 5p shakeup edges at 3228:56 AE 0:04 eV and 3233:43 AE 0:08 eV, respectively.…”

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confidence: 90%

Separation of Two-Electron Photoexcited Atomic Processes near the Inner-Shell Threshold

et al. 2009

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By means of a high resolution resonant inelastic x-ray scattering spectroscopy, we have for the first time separated spectral features pertaining to different two-electron atomic processes in the vicinity of an innershell threshold. Contributions of shakeoff, shakeup, and resonant 1s3p double excitations were extracted from the Ar KM-M 2;3 M x-ray satellite line intensity measured as a function of photon energy from ½1s3p double excitation threshold to saturation. The isolated ½1s3pnln 0 l 0 excitation spectrum is critically compared to the outcome of the multiconfiguration Dirac-Fock model with relaxation.According to the nature of photon-electron interaction a photon is absorbed only by a single electron. On the other hand, photoionization of an inner-shell electron is sometimes accompanied by removal of another electron (shakeoff) or its excitation into a higher empty atomic level (shakeup), and below the double photoionization threshold, doubly excited atomic states can be created. These multielectron excitations are straightforward manifestations of the breakdown of the independent electron picture as they appear due to the electron-electron interactions. Despite the persistent and intensive research the mechanisms of electron-electron correlations have not been fully elucidated yet. While the well-known shake mechanism (governed by monopole transitions between relaxed states) is commonly taken as a synonym for the double photoionization or excitation process, the presence of dynamical effects in the near-threshold region makes the interpretation of double photoexcitation spectra much more complicated.The main experimental problem hindering the study of near-threshold multielectron excitations is the overlap of the shakeoff, shakeup, and double excitation spectral contributions. Strong dependence of the shakeoff to shakeup probability ratio on the atomic number and atomic shell was employed to bypass this difficulty in some special cases. While the shakeup mechanism fully dominates the electron excitation following 1s photoionization of Be [1], the shakeoff prevails in the 1s2p double photoionization of mid-Z atoms [2]. It was found that a time-dependent perturbation theory [3] describes well the double photoionization of outer-shell electrons in low-Z atoms; for inner shells and higher Z atoms significant deviations were found [4,5], indicating that other mechanisms besides the shakeoff are at work. In the latest work a semiclassical knockout effect was suggested to dominate the near-threshold double 1s photoionization in 3d transition metals [6].One of the most interesting multielectron features is double excitations exhibiting discrete resonances in the preedge region. These processes are extremely weak when both electrons are excited from core levels, but they become more probable if a valence electron takes part in the excitation. In such cases structural solid-state effects obscure spectral details related to multiple atomic excitations, limiting such studies to gaseous atomic targets. This is the mai...

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confidence: 90%

Separation of Two-Electron Photoexcited Atomic Processes near the Inner-Shell Threshold

et al. 2009

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“…The continuous rise of the curve from zero at threshold is an indication that the satellites originate in a SO, rather than SU, process, since the later results in an intensity jump at the threshold (Å berg, 1972;Armen et al, 1985;Deutsch et al, 1996;Fritsch et al, 1998;Heiser et al, 1994). This is in full accord with the predicted intensity contribution of p1% (Deutsch et al, 1996;Fritsch et al, 1998) for SU in our case, as extrapolated from RMCDF calculations for Ar (Dyall, 1983;Mukoyama and Ito, 1994) and Kr (Wark et al, 1991). Note, however, that a KO process, the crosssection of which also rises continuously from zero, could also be a possible contributor.…”

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confidence: 89%

The evolution of inner-shell multielectronic X-ray spectra from threshold to saturation for low- to high-Z atoms

Diamant

Huotari

Hämäläinen

et al. 2006

Radiation Physics and Chemistry

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“…There have been dozens of experimental and theoretical investigations into the shake processes [17][18][19][20][21][22][23][24][25][26][27][28][29], and several advanced relativistic quantum mechanical techniques have been applied to characteristic diagram lines [30] or fewelectron scattering [31,32], though only Mukoyama [22] and Kochur [24] have performed ab initio calculations for the difficult transition metals. Due to both the experimental and computational difficulties involved in identifying satellite intensities empirically, there has been little comparison with experimental results in open-shell atoms.…”

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Ab initiodetermination of satellite intensities in transition-metal photoemission spectroscopy using a multiconfiguration framework

2011

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Following atomic photoionization, the abrupt change in potential can lead to secondary ionization of an outer-shell electron in a phenomenon known as shake-off, a process which gives rise to the asymmetric Kα profile and satellite lines. Investigation of chemical effects and relativistic quantum mechanics requires a theoretical determination of these satellite intensities; however, existing theoretical predictions are inconsistent with experimental results by up to an order of magnitude. Previously theoretical modeling required up to 12 fitting parameters to account for transition widths, energy corrections, spectator intensities, and spectator broadening. Using a multiconfiguration atomic model to account for electron-electron correlation, we provide here the first ab initio calculations of shake-off probabilities which are in agreement with experimental results (except for copper), an important step toward a complete theoretical profile.

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Shake theory predictions of excited-state populations following 1s ionisation in argon

Cited by 47 publications

References 19 publications

Separation of Two-Electron Photoexcited Atomic Processes near the Inner-Shell Threshold

Separation of Two-Electron Photoexcited Atomic Processes near the Inner-Shell Threshold

The evolution of inner-shell multielectronic X-ray spectra from threshold to saturation for low- to high-Z atoms

Ab initiodetermination of satellite intensities in transition-metal photoemission spectroscopy using a multiconfiguration framework

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