Effect of screening by external charges on the atomic orbitals and photoinduced processes within the Hartree-Fock-Slater atom

Thiele, R.; Son, Sang−Kil; Ziaja, Beata; Santra, Robin

doi:10.1103/physreva.86.033411

Cited by 23 publications

(22 citation statements)

References 60 publications

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“…They have also been used for xmolecule to calculate molecular electronic structure [59] and molecular data [60] to investigate molecular x-ray multiphoton ionization dynamics [60] and ultrafast explosion dynamics of small polyatomic molecules induced by intense XFEL pulses [61]. Lastly, xatom has been extended to treat atoms and ions immersed in a plasma environment to investigate ionization potential lowering in warm dense matter [62,63], which has further been employed for studying x-ray resonant magnetic scattering in materials [64]. Also note that the atomic electronic continuum states that are accurately calculated by xatom have been used for modeling high harmonic generation of rare gas atoms [65].…”

Section: Introductionmentioning

confidence: 99%

Compton spectra of atoms at high x-ray intensity

Son

Geffert

Santra

2017

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

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Abstract. Compton scattering is the nonresonant inelastic scattering of an xray photon by an electron and has been used to probe the electron momentum distribution in gas-phase and condensed-matter samples. In the low x-ray intensity regime, Compton scattering from atoms dominantly comes from bound electrons in neutral atoms, neglecting contributions from bound electrons in ions and free (ionized) electrons. In contrast, in the high x-ray intensity regime, the sample experiences severe ionization via x-ray multiphoton multiple ionization dynamics. Thus, it becomes necessary to take into account all the contributions to the Compton scattering signal when atoms are exposed to high-intensity x-ray pulses provided by x-ray free-electron lasers (XFELs). In this paper, we investigate the Compton spectra of atoms at high xray intensity, using an extension of the integrated x-ray atomic physics toolkit, xatom.As the x-ray fluence increases, there is a significant contribution from ionized electrons to the Compton spectra, which gives rise to strong deviations from the Compton spectra of neutral atoms. The present study provides not only understanding of the fundamental XFEL-matter interaction but also crucial information for single-particle imaging experiments, where Compton scattering is no longer negligible.

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Section: Introductionmentioning

confidence: 99%

Compton spectra of atoms at high x-ray intensity

Son

Geffert

Santra

2017

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

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“…The predictions for the IP lowering obtained with the extended HFS code [31] at the actual plasma conditions would place the IP shift between 5 − 10 eV for the Ar +0 . Such shift could then be detectable in the 'massively parallel' photoelectron spectra.…”

Section: Probing the Nanoplasma With An Ultraintense Ultrashort Softmentioning

confidence: 99%

“…[29,30]. Recently, a study on extending the atomistic Hartree-Fock-Slater (HFS) model to include the screening induced by external charges has been performed by Thiele et al [31].…”

Section: Introductionmentioning

confidence: 99%

Photoelectron spectroscopy method to reveal ionization potential lowering in nanoplasmas

Ziaja

Jurek

Medvedev

et al. 2013

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

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Abstract. Here we propose a scheme for probing the outer-shell atomic energy levels within a laser-created nanoplasma, using photoelectron spectroscopy data obtained from the irradiation of the nanoplasma with an ultraintense 'probing' pulse from soft X-ray free-electron laser. The proposed method can then detect shifts of outer-shell energy levels of an atom or an ion within a plasma, due to the effect of charged plasma environment on atomic potentials, known as the 'plasma screening effect'. Various theoretical models exist that estimate the magnitude of the screening effect. However, the first experimental data that can verify theoretical models have become available only recently (S. M. Vinko et al., Nature 482, 59 (2012)). They were obtained with a hard X-ray based experimental method which uses the information encoded in fluorescence spectra and is, therefore, restricted to deep atomic shells. Below we show that our photoelectron spectroscopy method of probing a nanoplasma with a destructive, high-intensity soft X-ray pulse that brings the irradiated system to the regime of 'massively parallel' ionization (Ch. Gnodtke, U. Saalmann, J.-M. Rost, Phys. Rev. Lett. 108, 175003 (2012)) enables the access to the information on the energy level (and ultimately energy level shift) of the valence orbital. In particular, the result of such photoelectron spectroscopy experiment could help clarifying the discrepancy between the ion abundances in nanoplasmas observed during the recent high-harmonic-generation and free-electron-laser experiments with intense soft X-ray pulses.

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“…One methodology is to calculate the effects of the screening in order to include them in the models. 7,[17][18][19][20] This works well for macroscopic treatments of the laser-cluster interaction which have their rates modified by the environment. Recently, experimental measurements were made which allow for a comparison of some of these macroscopic theoretical screening models with experimental data.…”

Section: Introductionmentioning

confidence: 99%

“…4,9,15,16 Atoms and ions in nanoplasmas will also have their ionization probabilities further altered due to electron and ion screening. 17,18 There have largely been two methodologies for dealing with these changes. One methodology is to calculate the effects of the screening in order to include them in the models.…”

Section: Introductionmentioning

confidence: 99%

A validation of a simple model for the calculation of the ionization energies in X-ray laser-cluster interactions

White

Ackad

2015

Physics of Plasmas

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The outer-ionization of an electron from a cluster is an unambiguous quantity, while the inner-ionization threshold is not, resulting in different microscopic quantum-classical hybrid models used in laser-cluster interactions. A simple local ionization threshold model for the change in the ionization energy is proposed and examined, for atoms and ions, at distances in between the initial configuration of the cluster to well into the cluster's disintegration. This model is compared with a full Hartree-Fock energy calculation which accounts for the electron correlation effects using the coupled cluster method with single and double excitations with perturbative triples (CCSD(T)). Good agreement is found between the two lending a strong theoretical support to works which rely on such models for the final and transient properties of the laser-cluster interaction.

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Effect of screening by external charges on the atomic orbitals and photoinduced processes within the Hartree-Fock-Slater atom

Cited by 23 publications

References 60 publications

Compton spectra of atoms at high x-ray intensity

Compton spectra of atoms at high x-ray intensity

Photoelectron spectroscopy method to reveal ionization potential lowering in nanoplasmas

A validation of a simple model for the calculation of the ionization energies in X-ray laser-cluster interactions

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