Many-electron correlations in photoabsorption in the M-shell of Ar

Amusia, M. Ya.; Cherepkov, N. A.; Чернышева, Л. В.

doi:10.1016/0375-9601(70)90348-8

Cited by 52 publications

(76 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The main contribution to E is given by the lowest, second-order diagram ( figure 1(a); it is convenient to show diagrams for the matrix element of the correlation potential between the initial and final projectile states f | E |i rather than for E (r, r ) itself). It was shown (see, e.g., Kelly 1963, Amusia andCherepkov 1975) that in electron scattering, besides the second-order diagrams, several important higher-order corrections (figures 1(b) and (c)) should also be taken into account (these diagrams are characterized as having two interactions between the projectile and the target atom), as well as the associated exchange diagrams. The correlation potential that results from the summation of these diagrams, hereafter we will call the polarization potential, pol E .…”

Section: Calculation Of the Correlation Potentialmentioning

confidence: 99%

“…The series of time-forward diagrams like that in figure 1 corresponding to a given hole orbital n can be taken into account by calculating the electron wavefunction in the loop of figure 1(a) in the field of this hole (Amusia and Cherepkov 1975). The summation over the intermediate states can be performed directly, by appropriately discretizing the projectile and excited electron continuum.…”

Section: Calculation Of the Correlation Potentialmentioning

confidence: 99%

See 1 more Smart Citation

Many-body calculations of positron scattering and annihilation from noble-gas atoms

Dzuba¹,

Flambaum²,

Gribakin³

et al. 1996

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

106

164

View full text Add to dashboard Cite

Abstract. We have applied many-body theory methods to study the interaction of low-energy positrons with noble-gas atoms. The positron-atom correlation potential includes explicitly the contribution from the target polarization by the positron and that from the virtual positronium (Ps) formation. It is demonstrated that the correlations and Ps formation (or tunnelling of electrons from the atom to the positron) create virtual levels in the positron-atom system. The existence of the virtual levels strongly influences the scattering and increases the positron annihilation rate by up to 400 times. The calculated elastic cross sections are in good agreement with experimental data. The inclusion of virtual Ps formation greatly improves the agreement with experimental annihilation rates with respect to calculations taking only the polarization into account. Our calculations have highlighted the difference between the calculation of positronatom scattering and the calculation of corresponding annihilation rates. The annihilation rate is very sensitive to the behaviour of the wavefunction at small positron-electron separations. A simple approximate formula based on the Sommerfeld factor is suggested to account for the effect of electron-positron Coulomb attraction on the annihilation rates.

show abstract

Section: Calculation Of the Correlation Potentialmentioning

confidence: 99%

Section: Calculation Of the Correlation Potentialmentioning

confidence: 99%

Many-body calculations of positron scattering and annihilation from noble-gas atoms

Dzuba¹,

Flambaum²,

Gribakin³

et al. 1996

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

106

164

View full text Add to dashboard Cite

show abstract

“…These resonance-like peaks in atomic photoionization spectra have also been interpreted as originating from a collective (i.e., many-electron) oscillation of the atomic electrons [20,39] in analogy to the well-known giant dipole resonance in nuclear physics. However, since such resonance-like peaks in the photoionization spectra for particular subshells do occur within a single-active-electron model of an atom (which by definition does not include any electron correlations), the qualitative description of the phenomenon as a potential-barrier effect is justified.…”

Section: Introductionmentioning

confidence: 94%

“…A rather complete understanding exists for the linear process of atomic photoionization (see, e.g., the detailed analyses in Refs. [19][20][21]), but it remains to be determined to what extent that understanding applies to nonlinear processes such as multiphoton ionization. For atoms larger than He, a number of theoretical treatments of few-photon ionization processes including electron correlation effects have been carried out [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], primarily for valence-shell electrons and for photon energies in the UV regime.…”

Section: Introductionmentioning

confidence: 99%

“…However, since such resonance-like peaks in the photoionization spectra for particular subshells do occur within a single-active-electron model of an atom (which by definition does not include any electron correlations), the qualitative description of the phenomenon as a potential-barrier effect is justified. Accurate treatment of electron correlations is necessary to describe the effects on other subshell spectra (via interchannel interactions) and to provide quantitatively accurate predictions [20,21].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Potential-barrier effects in three-photon-ionization processes

Starace

2014

Phys. Rev. A

View full text Add to dashboard Cite

Resonance-like enhancements of generalized three-photon cross sections for extreme ultraviolet ionization of Ar, Kr, and Xe are demonstrated and analyzed within a single-active-electron, central-potential model. The resonant-like behavior is shown to originate from the potential barriers experienced by intermediate-and final-state photoelectron wave packets corresponding to absorption of one, two, or three photons. The resonance-like profiles in the generalized three-photon-ionization cross sections are shown to be similar to those found in the generalized two-photon-ionization cross sections [Phys. Rev. A 82, 053414 (2010)]. The complexity of Cooper minima in multiphoton-ionization processes is also discussed. Owing to the similar resonance-like profiles found in both two-and three-photon generalized cross sections, we expect such potential-barrier effects to be general features of multiphoton-ionization processes in most atoms with occupied p and d subshells.

show abstract

New developments in the theory of molecular K‐shell photoionization

Cherepkov

Semenov

2007

Int J of Quantum Chemistry

View full text Add to dashboard Cite

ABSTRACT:A new version of the relaxed core Hartree-Fock approximation with a fractional charge of the molecular ion state is applied for calculations of molecular photoionization processes. The set of continuous spectrum wave functions obtained by that method is used when taking many-electron correlations into account in the framework of the random-phase approximation. The vibrational motion is also included into consideration. In that way, the most reliable results for the vibrationally resolved partial photoionization cross sections and the angular asymmetry parameter ␤ for the K-shells of CO and N 2 molecules have been obtained. A good agreement with the stateof-the-art experimental data is demonstrated. From our calculations it follows that the nondipole effects for the K-shells of N 2 and CO molecules are small near the ionization thresholds, in agreement with the latest experimental data. Two predictions have been made based on these calculations. One of them is the appearance of the correlational maximum in the photoionization cross section of the 1 u shell of N 2 molecule near the * shape resonance, which is now fully confirmed by the experiment. The second prediction concerns the behavior of the nondipole parameters for the 1 g and 1 u shells of N 2 . According to our calculation, they oscillate in antiphase with rather large amplitudes around the unresolved values, so that after summation of the contributions of the two K-shells, the oscillations practically disappear. This prediction does not yet have an experimental confirmation.

show abstract

Many-electron correlations in photoabsorption in the M-shell of Ar

Cited by 52 publications

References 2 publications

Many-body calculations of positron scattering and annihilation from noble-gas atoms

Many-body calculations of positron scattering and annihilation from noble-gas atoms

Potential-barrier effects in three-photon-ionization processes

New developments in the theory of molecular K‐shell photoionization

Contact Info

Product

Resources

About