Ya Amusia - Academia.edu (original) (raw)

Papers by Ya Amusia

Research paper thumbnail of Qualitative Modification of the High Energy Atomic Photoionization Cross Section

Physical Review Letters, 2000

It is demonstrated that the nonrelativistic high energy omega-->infinity behavior of the p... more It is demonstrated that the nonrelativistic high energy omega-->infinity behavior of the photoionization cross section of an nl atomic subshell, sigma(nl)(omega), for l>0 is independent of l and is given by sigma(nl)(omega) approximately 1/omega(9/2), rather than the previously generally accepted sigma(nl)(omega) approximately 1/omega(l+7/2). Furthermore, for l = 1, although the exponent does not change, the coefficient is significantly altered. This modification of sigma(nl)(omega) is due to the interchannel interaction between ns photoionization channels and l not equal0 channels in the atom. As a result, for the photoionization of l not equal0 electrons, the single-particle approximation is never correct in the omega-->infinity limit. This has important consequences for sum rule calculations.

Research paper thumbnail of Modification of the Xe 4d giant resonance by the C60 shell in molecular Xe@C60

Journal of Experimental and Theoretical Physics, 2006

It is demonstrated that in photoabsorption of the 4 d 10 subshell of a Xe atom in molecular Xe@C ... more It is demonstrated that in photoabsorption of the 4 d 10 subshell of a Xe atom in molecular Xe@C 60 , the 4 d giant resonance that characterizes the isolated Xe atom is distorted significantly. The reflection of photoelectron waves by the C 60 shell leads to profound oscillations in the photoionization cross section such that the Xe giant resonance is transformed into four strong peaks. Similarly, the angular anisotropy parameters, both dipole and nondipole, are also modified. The method of calculation is based on the approximation of the C 60 shell by an infinitely thin bubble potential that leaves the sum rule for the 4 d -electrons almost unaffected, but noticeably modifies the dipole polarizability of the 4 d-shell.

Research paper thumbnail of Characteristic features in photoionisation of excited atomic states

Journal of Physics B: Atomic and Molecular Physics, 1983

ABSTRACT

Research paper thumbnail of Photoionization accompanied by excitation at intermediate photon energies

Physical Review A, 2008

We calculate the photoionization-with-excitation to photoionization ratios R nl and R n = ⌺ l R n... more We calculate the photoionization-with-excitation to photoionization ratios R nl and R n = ⌺ l R nl for atomic helium and positive heliumlike ions at intermediate values of the photon energies. The final-state interactions between the electrons are included in the lowest order of their Sommerfeld parameter. This enables us, in contrast to purely numerical calculations, to investigate the roles of various mechanisms contributing beyond the high-energy limit. The system of two bound electrons is described by the functions obtained by the correlation function hyperspherical harmonic method. For the case of heliumlike ions we present the highenergy limits as a power expansion in the inverse charge of the nucleus. We analyze the contribution of excitation of states with nonzero orbital momenta to the ratios R n . In the case of helium our results for R n are in good agreement with those of experiments and of previous calculations.

Research paper thumbnail of Recoil momenta distributions in the double photoionization

Journal of Physics: Conference Series, 2014

ABSTRACT We calculate the distributions in recoil momenta for the high energy double photoionizat... more ABSTRACT We calculate the distributions in recoil momenta for the high energy double photoionization of helium caused by quasifree mechanism. The distributions obtain local maxima at small values of the recoil momenta. This agrees with earlier predictions and recent experimental data. Angular correlations which reach the largest value for "back-to-back" configuration of photoelectrons are also obtained.

Research paper thumbnail of Quasifree Mechanism in Ionization Processes

Physica Scripta, 2005

We discuss a specific quasifree mechanism (QFM) of the ionization processes, which requires only ... more We discuss a specific quasifree mechanism (QFM) of the ionization processes, which requires only small momentum transfer to the nucleus. The QFM mechanism is important in the kinematical regions where the two-electron system can absorb a photon without participation of the nucleus. The QFM leads to the complicated shape of the double photoionization spectrum curve, providing the breakdown of the nonrelativistic high energy asymptotic of the double-to single photoionization ratio. Calculation of the QFM contribution requires a consistent theoretical approach. Use of oversimplified approximations leads to misleading results. In certain kinematical regions the QFM provides the leading contribution, and thus the results obtained without inclusion of QFM are erroneous. Experimental detection of QFM is a complicated, but interesting problem.

Research paper thumbnail of Inter-shell correlations in the formation of singly charged ions near the Ar L-shell ionisation threshold

Journal of Physics B-atomic Molecular and Optical Physics, 1977

The yield of singly charged ions is considered for inelastic fast-electron scattering. The densit... more The yield of singly charged ions is considered for inelastic fast-electron scattering. The densities of the generalised oscillator strengths are calculated in the single-electron approximation, taking account of the many-electron inter-shell correlations in the RPAE framework and out of it. It is demonstrated that a special type of inter-shell interaction of the electrons is responsible for this effect. This interaction

Research paper thumbnail of The effect of atomic rearrangement on the photoionisation cross section for 3d subshells of the isoelectronic Xe series

Journal of Physics B: Atomic and Molecular Physics, 1985

The photoionisation cross sections for 3d10 subshells are calculated for the elements of the isoe... more The photoionisation cross sections for 3d10 subshells are calculated for the elements of the isoelectronic series of atomic Xe such as I-, Xe, Cs+, Ba2+ and La3+. The non-relativistic random-phase approximation with exchange (RPAE) is used to account for the static rearrangement. The maxima in Xe and I- spectra are due to the 3d- epsilon f transition into the continuum, and those for Ba2+ and La3+ are due to 3d-4f transitions to discrete levels. The photoabsorption cross section for Cs+ appears to be sensitive to the method of calculation; RPAE leads to maxima in the discrete spectrum, whereas the static rearrangement leads to a maximum in the continuum. Allowance for the rearrangement due to a 3d-vacancy decay lowers the cross section in the continuum, shifting the oscillator strengths to the discrete spectrum which reveals the existence of the so-called 'collapse' of the 4f electron.

Research paper thumbnail of Computation of the anomaly in the hyperfine splitting in Li + ions

Journal of Physics B: Atomic and Molecular Physics, 1983

Computation of hyperfine splitting in the 1s2s (23S1) state of two-electron systems 6,7Li+ has be... more Computation of hyperfine splitting in the 1s2s (23S1) state of two-electron systems 6,7Li+ has been carried out. The ratio of the splitting intervals in such a state deviates from the Lande rule. This deviation is caused by an additional shift delta of the triplet level corresponding to the quantum number F equal to I, I being the nuclear spin. It

Research paper thumbnail of Strong electron correlation in photoionization of spin-orbit doublets

Physical review letters, Jan 4, 2002

A new and explicitly many-body aspect of the "leveraging" of the spin-orbit interaction... more A new and explicitly many-body aspect of the "leveraging" of the spin-orbit interaction is demonstrated, spin-orbit activated interchannel coupling, which can significantly alter the photoionization cross section of a spin-orbit doublet. As an example, it is demonstrated via a modified version of the spin-polarized random phase approximation with exchange, that a recently observed unexplained structure in the Xe 3d(5/2) photoionization cross section [A. Kivimäki et al., Phys. Rev. A 63, 012716 (2000)] is entirely due to this effect. Similar features are predicted for Cs 3d(5/2) and Ba 3d(5/2).

Research paper thumbnail of Inter-shell correlations in the formation of singly charged ions near the Ar L-shell ionisation threshold

Journal of Physics B: Atomic and Molecular Physics, 1977

The yield of singly charged ions is considered for inelastic fast-electron scattering. The densit... more The yield of singly charged ions is considered for inelastic fast-electron scattering. The densities of the generalised oscillator strengths are calculated in the single-electron approximation, taking account of the many-electron inter-shell correlations in the RPAE framework and out of it. It is demonstrated that a special type of inter-shell interaction of the electrons is responsible for this effect. This interaction

Research paper thumbnail of Quadrupole moment of atoms with the ground-state term P 1/2

Journal of Physics B: Atomic and Molecular Physics, 1986

ABSTRACT The results of the quadrupole moment Q calculations in those atoms where the total momen... more ABSTRACT The results of the quadrupole moment Q calculations in those atoms where the total moment of all the electron shells j=1/2 are presented. It is shown that the non-zero quadrupole moment arises due to the hyperfine interaction of the electron shell with the nucleus. The Q values turn out to be especially large in cases when the atoms have the term 2P1/2.

Research paper thumbnail of A study of the Ne 2s2p 5 ( 3 P)3s and 3p correlation satellites up to 75 eV above threshold

Journal of Physics B: Atomic, Molecular and Optical Physics, 2010

The 2s2p 5 ( 3 P)3s 2 P, 3p 2 D and 2 S satellite states of neon have been studied at several ene... more The 2s2p 5 ( 3 P)3s 2 P, 3p 2 D and 2 S satellite states of neon have been studied at several energies from 5 to 75 eV above their respective thresholds. The relative intensities of the satellite states with respect to their main lines shed light on the nature of the many-electron correlations leading to the formation of these satellites. The experimental results are compared with a calculation which makes use of a random phase approximation with exchange (RPAE) cross sections, and takes into account the shake-up and direct knock-out channels as well as their interference.

Research paper thumbnail of On the distribution of electrons in the double ionization of helium-like ions by Compton scattering

Journal of Physics B: Atomic, Molecular and Optical Physics, 2003

The Compton scattering of a high energy photon by a helium-like ion, followed by the ionization o... more The Compton scattering of a high energy photon by a helium-like ion, followed by the ionization of two electrons, is considered outside of the Bethe surface of Compton scattering with the knock-out of a single electron. The role of shake-off (SO), of final state interactions (FSI) and of the quasi-free mechanism (QFM) is analysed. The triple and double differential distributions are calculated. It is demonstrated for the first time that in certain kinematical regions the process is dominated by the FSI and by the QFM, while the SO contribution is much smaller.

Research paper thumbnail of Excitation of lower autoionization states of the helium-like ions in x-ray scattering

Journal of Physics B: Atomic, Molecular and Optical Physics, 1999

ABSTRACT

Research paper thumbnail of Non-dipole angular anisotropy parameters of photoelectrons from semi-filled shell atoms

Journal of Physics B: Atomic, Molecular and Optical Physics, 2006

We present the results of calculations of outer and next to the outer shell non-dipole angular an... more We present the results of calculations of outer and next to the outer shell non-dipole angular anisotropy parameters of photoelectrons for semi-filled shell atoms in the Hartree-Fock (HF) one-electron approximation and with account of inter-electron correlations in the frame of the Spin Polarized Random Phase Approximation with Exchange (SP RPAE). We demonstrate for the first time that this characteristic of photoionization process is essentially sensitive to the fact whether the photoelectron has the same or opposite spin orientation to that of the semi-filled shell.

Research paper thumbnail of Effects of spin–orbit activated interchannel coupling on dipole photoelectron angular distribution asymmetry parameters

Journal of Physics B: Atomic, Molecular and Optical Physics, 2004

The effects of spin–orbit induced interchannel coupling on the dipole photoelectron angular asymm... more The effects of spin–orbit induced interchannel coupling on the dipole photoelectron angular asymmetry parameter β3d for Xe, Cs and Ba are explored using a modified version of the spin-polarized random phase approximation with exchange (SPRPAE) methodology. For Xe, is modified somewhat by the interchannel coupling in the vicinity of the 3d3/2 → ϵf shape resonance, and this effect is significantly more pronounced in Cs where the resonance is larger. In Ba, however, where f-wave orbital collapse has occurred, the shape resonance has moved below threshold and the effect of interchannel coupling on above the 3d3/2 threshold is negligible. But below the 3d3/2 threshold, is dominated by the huge broad 3d3/2 → 4f resonance.

Research paper thumbnail of Test of a q -fractional V ( N - q ) Hartree-Fock potential for the calculation of double photoionization cross sections of neon

Journal of Physics B: Atomic, Molecular and Optical Physics, 2001

The approach of a parametric V(N-q) Hartree-Fock potential with fractional q is developed and app... more The approach of a parametric V(N-q) Hartree-Fock potential with fractional q is developed and applied for the first time for the calculation of the double photoionization cross sections of Ne. A minimum of the squared difference between the length-form and velocity-form cross sections is used as a criterion for calculating the values of q. It is found that the minimization

Research paper thumbnail of Non-dipole effects in spin polarization of photoelectrons from Xe 4p and 5p shells

Journal of Physics B: Atomic, Molecular and Optical Physics, 2001

Page 1. Non-dipole effects in spin polarization of photoelectrons from Xe 4p and 5p shells This a... more Page 1. Non-dipole effects in spin polarization of photoelectrons from Xe 4p and 5p shells This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2001 J. Phys. B: At. Mol. Opt. Phys. 34 L211 ...

Research paper thumbnail of Double electron ionization in Compton scattering of high energy photons by helium atoms

Journal of Physics B: Atomic, Molecular and Optical Physics, 1995

The cross section of double-electron ionization of two-electron atoms and ions in Compton scatter... more The cross section of double-electron ionization of two-electron atoms and ions in Compton scattering of high energy photons is calculated. It is demonstrated that its dependence on incoming photon frequency is the same as that for the single-electron ionization. The ratio "double-to-single" ionization in Compton scattering proved to be energy independent and almost coincides with the corresponding value for photoionization. For the He atom it is 1.68%. This surprising result deserves experimental verification.

Research paper thumbnail of Qualitative Modification of the High Energy Atomic Photoionization Cross Section

Physical Review Letters, 2000

It is demonstrated that the nonrelativistic high energy omega-->infinity behavior of the p... more It is demonstrated that the nonrelativistic high energy omega-->infinity behavior of the photoionization cross section of an nl atomic subshell, sigma(nl)(omega), for l>0 is independent of l and is given by sigma(nl)(omega) approximately 1/omega(9/2), rather than the previously generally accepted sigma(nl)(omega) approximately 1/omega(l+7/2). Furthermore, for l = 1, although the exponent does not change, the coefficient is significantly altered. This modification of sigma(nl)(omega) is due to the interchannel interaction between ns photoionization channels and l not equal0 channels in the atom. As a result, for the photoionization of l not equal0 electrons, the single-particle approximation is never correct in the omega-->infinity limit. This has important consequences for sum rule calculations.

Research paper thumbnail of Modification of the Xe 4d giant resonance by the C60 shell in molecular Xe@C60

Journal of Experimental and Theoretical Physics, 2006

It is demonstrated that in photoabsorption of the 4 d 10 subshell of a Xe atom in molecular Xe@C ... more It is demonstrated that in photoabsorption of the 4 d 10 subshell of a Xe atom in molecular Xe@C 60 , the 4 d giant resonance that characterizes the isolated Xe atom is distorted significantly. The reflection of photoelectron waves by the C 60 shell leads to profound oscillations in the photoionization cross section such that the Xe giant resonance is transformed into four strong peaks. Similarly, the angular anisotropy parameters, both dipole and nondipole, are also modified. The method of calculation is based on the approximation of the C 60 shell by an infinitely thin bubble potential that leaves the sum rule for the 4 d -electrons almost unaffected, but noticeably modifies the dipole polarizability of the 4 d-shell.

Research paper thumbnail of Characteristic features in photoionisation of excited atomic states

Journal of Physics B: Atomic and Molecular Physics, 1983

ABSTRACT

Research paper thumbnail of Photoionization accompanied by excitation at intermediate photon energies

Physical Review A, 2008

We calculate the photoionization-with-excitation to photoionization ratios R nl and R n = ⌺ l R n... more We calculate the photoionization-with-excitation to photoionization ratios R nl and R n = ⌺ l R nl for atomic helium and positive heliumlike ions at intermediate values of the photon energies. The final-state interactions between the electrons are included in the lowest order of their Sommerfeld parameter. This enables us, in contrast to purely numerical calculations, to investigate the roles of various mechanisms contributing beyond the high-energy limit. The system of two bound electrons is described by the functions obtained by the correlation function hyperspherical harmonic method. For the case of heliumlike ions we present the highenergy limits as a power expansion in the inverse charge of the nucleus. We analyze the contribution of excitation of states with nonzero orbital momenta to the ratios R n . In the case of helium our results for R n are in good agreement with those of experiments and of previous calculations.

Research paper thumbnail of Recoil momenta distributions in the double photoionization

Journal of Physics: Conference Series, 2014

ABSTRACT We calculate the distributions in recoil momenta for the high energy double photoionizat... more ABSTRACT We calculate the distributions in recoil momenta for the high energy double photoionization of helium caused by quasifree mechanism. The distributions obtain local maxima at small values of the recoil momenta. This agrees with earlier predictions and recent experimental data. Angular correlations which reach the largest value for "back-to-back" configuration of photoelectrons are also obtained.

Research paper thumbnail of Quasifree Mechanism in Ionization Processes

Physica Scripta, 2005

We discuss a specific quasifree mechanism (QFM) of the ionization processes, which requires only ... more We discuss a specific quasifree mechanism (QFM) of the ionization processes, which requires only small momentum transfer to the nucleus. The QFM mechanism is important in the kinematical regions where the two-electron system can absorb a photon without participation of the nucleus. The QFM leads to the complicated shape of the double photoionization spectrum curve, providing the breakdown of the nonrelativistic high energy asymptotic of the double-to single photoionization ratio. Calculation of the QFM contribution requires a consistent theoretical approach. Use of oversimplified approximations leads to misleading results. In certain kinematical regions the QFM provides the leading contribution, and thus the results obtained without inclusion of QFM are erroneous. Experimental detection of QFM is a complicated, but interesting problem.

Research paper thumbnail of Inter-shell correlations in the formation of singly charged ions near the Ar L-shell ionisation threshold

Journal of Physics B-atomic Molecular and Optical Physics, 1977

The yield of singly charged ions is considered for inelastic fast-electron scattering. The densit... more The yield of singly charged ions is considered for inelastic fast-electron scattering. The densities of the generalised oscillator strengths are calculated in the single-electron approximation, taking account of the many-electron inter-shell correlations in the RPAE framework and out of it. It is demonstrated that a special type of inter-shell interaction of the electrons is responsible for this effect. This interaction

Research paper thumbnail of The effect of atomic rearrangement on the photoionisation cross section for 3d subshells of the isoelectronic Xe series

Journal of Physics B: Atomic and Molecular Physics, 1985

The photoionisation cross sections for 3d10 subshells are calculated for the elements of the isoe... more The photoionisation cross sections for 3d10 subshells are calculated for the elements of the isoelectronic series of atomic Xe such as I-, Xe, Cs+, Ba2+ and La3+. The non-relativistic random-phase approximation with exchange (RPAE) is used to account for the static rearrangement. The maxima in Xe and I- spectra are due to the 3d- epsilon f transition into the continuum, and those for Ba2+ and La3+ are due to 3d-4f transitions to discrete levels. The photoabsorption cross section for Cs+ appears to be sensitive to the method of calculation; RPAE leads to maxima in the discrete spectrum, whereas the static rearrangement leads to a maximum in the continuum. Allowance for the rearrangement due to a 3d-vacancy decay lowers the cross section in the continuum, shifting the oscillator strengths to the discrete spectrum which reveals the existence of the so-called 'collapse' of the 4f electron.

Research paper thumbnail of Computation of the anomaly in the hyperfine splitting in Li + ions

Journal of Physics B: Atomic and Molecular Physics, 1983

Computation of hyperfine splitting in the 1s2s (23S1) state of two-electron systems 6,7Li+ has be... more Computation of hyperfine splitting in the 1s2s (23S1) state of two-electron systems 6,7Li+ has been carried out. The ratio of the splitting intervals in such a state deviates from the Lande rule. This deviation is caused by an additional shift delta of the triplet level corresponding to the quantum number F equal to I, I being the nuclear spin. It

Research paper thumbnail of Strong electron correlation in photoionization of spin-orbit doublets

Physical review letters, Jan 4, 2002

A new and explicitly many-body aspect of the "leveraging" of the spin-orbit interaction... more A new and explicitly many-body aspect of the "leveraging" of the spin-orbit interaction is demonstrated, spin-orbit activated interchannel coupling, which can significantly alter the photoionization cross section of a spin-orbit doublet. As an example, it is demonstrated via a modified version of the spin-polarized random phase approximation with exchange, that a recently observed unexplained structure in the Xe 3d(5/2) photoionization cross section [A. Kivimäki et al., Phys. Rev. A 63, 012716 (2000)] is entirely due to this effect. Similar features are predicted for Cs 3d(5/2) and Ba 3d(5/2).

Research paper thumbnail of Inter-shell correlations in the formation of singly charged ions near the Ar L-shell ionisation threshold

Journal of Physics B: Atomic and Molecular Physics, 1977

The yield of singly charged ions is considered for inelastic fast-electron scattering. The densit... more The yield of singly charged ions is considered for inelastic fast-electron scattering. The densities of the generalised oscillator strengths are calculated in the single-electron approximation, taking account of the many-electron inter-shell correlations in the RPAE framework and out of it. It is demonstrated that a special type of inter-shell interaction of the electrons is responsible for this effect. This interaction

Research paper thumbnail of Quadrupole moment of atoms with the ground-state term P 1/2

Journal of Physics B: Atomic and Molecular Physics, 1986

ABSTRACT The results of the quadrupole moment Q calculations in those atoms where the total momen... more ABSTRACT The results of the quadrupole moment Q calculations in those atoms where the total moment of all the electron shells j=1/2 are presented. It is shown that the non-zero quadrupole moment arises due to the hyperfine interaction of the electron shell with the nucleus. The Q values turn out to be especially large in cases when the atoms have the term 2P1/2.

Research paper thumbnail of A study of the Ne 2s2p 5 ( 3 P)3s and 3p correlation satellites up to 75 eV above threshold

Journal of Physics B: Atomic, Molecular and Optical Physics, 2010

The 2s2p 5 ( 3 P)3s 2 P, 3p 2 D and 2 S satellite states of neon have been studied at several ene... more The 2s2p 5 ( 3 P)3s 2 P, 3p 2 D and 2 S satellite states of neon have been studied at several energies from 5 to 75 eV above their respective thresholds. The relative intensities of the satellite states with respect to their main lines shed light on the nature of the many-electron correlations leading to the formation of these satellites. The experimental results are compared with a calculation which makes use of a random phase approximation with exchange (RPAE) cross sections, and takes into account the shake-up and direct knock-out channels as well as their interference.

Research paper thumbnail of On the distribution of electrons in the double ionization of helium-like ions by Compton scattering

Journal of Physics B: Atomic, Molecular and Optical Physics, 2003

The Compton scattering of a high energy photon by a helium-like ion, followed by the ionization o... more The Compton scattering of a high energy photon by a helium-like ion, followed by the ionization of two electrons, is considered outside of the Bethe surface of Compton scattering with the knock-out of a single electron. The role of shake-off (SO), of final state interactions (FSI) and of the quasi-free mechanism (QFM) is analysed. The triple and double differential distributions are calculated. It is demonstrated for the first time that in certain kinematical regions the process is dominated by the FSI and by the QFM, while the SO contribution is much smaller.

Research paper thumbnail of Excitation of lower autoionization states of the helium-like ions in x-ray scattering

Journal of Physics B: Atomic, Molecular and Optical Physics, 1999

ABSTRACT

Research paper thumbnail of Non-dipole angular anisotropy parameters of photoelectrons from semi-filled shell atoms

Journal of Physics B: Atomic, Molecular and Optical Physics, 2006

We present the results of calculations of outer and next to the outer shell non-dipole angular an... more We present the results of calculations of outer and next to the outer shell non-dipole angular anisotropy parameters of photoelectrons for semi-filled shell atoms in the Hartree-Fock (HF) one-electron approximation and with account of inter-electron correlations in the frame of the Spin Polarized Random Phase Approximation with Exchange (SP RPAE). We demonstrate for the first time that this characteristic of photoionization process is essentially sensitive to the fact whether the photoelectron has the same or opposite spin orientation to that of the semi-filled shell.

Research paper thumbnail of Effects of spin–orbit activated interchannel coupling on dipole photoelectron angular distribution asymmetry parameters

Journal of Physics B: Atomic, Molecular and Optical Physics, 2004

The effects of spin–orbit induced interchannel coupling on the dipole photoelectron angular asymm... more The effects of spin–orbit induced interchannel coupling on the dipole photoelectron angular asymmetry parameter β3d for Xe, Cs and Ba are explored using a modified version of the spin-polarized random phase approximation with exchange (SPRPAE) methodology. For Xe, is modified somewhat by the interchannel coupling in the vicinity of the 3d3/2 → ϵf shape resonance, and this effect is significantly more pronounced in Cs where the resonance is larger. In Ba, however, where f-wave orbital collapse has occurred, the shape resonance has moved below threshold and the effect of interchannel coupling on above the 3d3/2 threshold is negligible. But below the 3d3/2 threshold, is dominated by the huge broad 3d3/2 → 4f resonance.

Research paper thumbnail of Test of a q -fractional V ( N - q ) Hartree-Fock potential for the calculation of double photoionization cross sections of neon

Journal of Physics B: Atomic, Molecular and Optical Physics, 2001

The approach of a parametric V(N-q) Hartree-Fock potential with fractional q is developed and app... more The approach of a parametric V(N-q) Hartree-Fock potential with fractional q is developed and applied for the first time for the calculation of the double photoionization cross sections of Ne. A minimum of the squared difference between the length-form and velocity-form cross sections is used as a criterion for calculating the values of q. It is found that the minimization

Research paper thumbnail of Non-dipole effects in spin polarization of photoelectrons from Xe 4p and 5p shells

Journal of Physics B: Atomic, Molecular and Optical Physics, 2001

Page 1. Non-dipole effects in spin polarization of photoelectrons from Xe 4p and 5p shells This a... more Page 1. Non-dipole effects in spin polarization of photoelectrons from Xe 4p and 5p shells This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2001 J. Phys. B: At. Mol. Opt. Phys. 34 L211 ...

Research paper thumbnail of Double electron ionization in Compton scattering of high energy photons by helium atoms

Journal of Physics B: Atomic, Molecular and Optical Physics, 1995

The cross section of double-electron ionization of two-electron atoms and ions in Compton scatter... more The cross section of double-electron ionization of two-electron atoms and ions in Compton scattering of high energy photons is calculated. It is demonstrated that its dependence on incoming photon frequency is the same as that for the single-electron ionization. The ratio "double-to-single" ionization in Compton scattering proved to be energy independent and almost coincides with the corresponding value for photoionization. For the He atom it is 1.68%. This surprising result deserves experimental verification.