Higher retardation and multipole corrections to the dipole angular distribution of 1<i>s</i>photoelectrons at low energies

Bechler, A.; Pratt, R.H.

doi:10.1103/physreva.39.1774

Cited by 90 publications

(66 citation statements)

References 8 publications

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“…The lack of retardation corrections to the imaginary anomalous scattering factor is an artifact of the hydrogenic formalism used here. It has been shown that such corrections do exist in neutral atoms (Bechler & Pratt, 1989). …”

Section: Numerical Resultsmentioning

confidence: 99%

Investigation of the Angle Dependence of the Photon–Atom Anomalous Scattering Factors

Bergstrom

Kissel²,

Pratt³

et al. 1997

Acta Cryst Sect A

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The angle dependence of the elastic photon-atom scattering amplitude is investigated using full relativistic S-matrix calculations for guidance. A simple quantitative approach is developed based on the full nonrelativistic amplitude for Rayleigh scattering from the ground state of a hydrogenic ion and it is successfully applied to neutral atoms of low and intermediate nuclear charge. This framework is useful for scattering of X-rays with energies above the K-shell ionization threshold but below energies where major relativistic corrections are necessary. The generalized anomalous scattering factors presented here go beyond the usual angle-independent anomalous-scattering-factor approximation, permitting a discussion of the full angular dependence of the anomalous scattering factors. Simple formulas, expressed in terms of elementary functions and a loOkup table, are presented for these generalized anomalous scattering factors. Numerical examples illustrate that the angle dependence can be substantial. A fairly good representation of full numerical results is achieved.

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Section: Numerical Resultsmentioning

confidence: 99%

Investigation of the Angle Dependence of the Photon–Atom Anomalous Scattering Factors

Bergstrom

Kissel²,

Pratt³

et al. 1997

Acta Cryst Sect A

Self Cite

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“…At these high energies, non-dipole effects are expected to occur. One has to distinguish between first-order non-dipole effects that cause a forward/backward asymmetry in the angular distribution 27,28 and second-order non-dipole effects that influence also the plane perpendicular to the propagation direction of the light 18 ; note that this plane is traditionally referred to as the dipole plane.…”

Section: Resultsmentioning

confidence: 99%

Atomic Auger Doppler effects upon emission of fast photoelectrons

et al. 2014

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Studies of photoemission processes induced by hard X-rays including production of energetic electrons have become feasible due to recent substantial improvement of instrumentation. Novel dynamical phenomena have become possible to investigate in this new regime. Here we show a significant change in Auger emission following 1s photoionization of neon, which we attribute to the recoil of the Ne ion induced by the emission of a fast photoelectron. Because of the preferential motion of the ionized Ne atoms along two opposite directions, an Auger Doppler shift is revealed, which manifests itself as a gradual broadening and doubling of the Auger spectral features. This Auger Doppler effect should be a general phenomenon in high-energy photoemission of both isolated atoms and molecules, which will have to be taken into account in studies of other recoil effects such as vibrational or rotational recoil in molecules, and may also have consequences in measurements in solids.

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“…Screened wave functions have been used to accurately calculate nondipole asymmetries of atoms over energy ranges extending from near threshold to thousands of electron volts [21][22][23]. Since nondipole asymmetries are generally proportional to the photon momentum or energy, relatively large asymmetries are observed for inner-shell electrons in the x-ray regime [23,28].…”

Section: Introductionmentioning

confidence: 99%

“…This model neglects screening and may be inaccurate as the energy is lowered toward threshold [21][22][23]. Recent theories adopt the "first retardation correction" to the dipole approximation, which includes cross terms of electric dipole (E1) photoionization amplitudes with electric quadrupole (E2) and magnetic dipole (M1) amplitudes [21,22,[24][25][26]. For photoionization of randomly oriented atoms or molecules by a linearly polarized photon beam, the differential cross section can be expressed as [24] dσ d (θ,φ) = σ 4π {1 + β e P 2 (cos θ ) + (δ + γ cos 2 θ ) sin θ cos φ}, (1) where σ is the angle-integrated cross section, β e is the electric dipole anisotropy parameter, P 2 (cos θ ) = (3 cos 2 θ − 1)/2 is the second Legendre polynomial, and δ and γ are the first-order nondipole asymmetry parameters resulting from E1-E2 and E1-M1 cross terms.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dipole and nondipole photoionization of molecular hydrogen

et al. 2015

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We describe a theoretical approach to molecular photoionization that includes first-order corrections to the dipole approximation. The theoretical formalism is presented and applied to photoionization of H 2 over the 20-to 180-eV photon energy range. The angle-integrated cross section σ , the electric dipole anisotropy parameter β e , the molecular alignment anisotropy parameter β m , and the first-order nondipole asymmetry parameters γ and δ were calculated within the single-channel, static-exchange approximation. The calculated parameters are compared with previous measurements of σ and β m and the present measurements of β e and γ + 3δ. The dipole and nondipole angular distribution parameters were determined simultaneously using an efficient, multiangle measurement technique. Good overall agreement is observed between the magnitudes and spectral variations of the calculated and measured parameters. The nondipole asymmetries of He 1s and Ne 2p photoelectrons were also measured in the course of this work.

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Higher retardation and multipole corrections to the dipole angular distribution of 1sphotoelectrons at low energies

Cited by 90 publications

References 8 publications

Investigation of the Angle Dependence of the Photon–Atom Anomalous Scattering Factors

Investigation of the Angle Dependence of the Photon–Atom Anomalous Scattering Factors

Atomic Auger Doppler effects upon emission of fast photoelectrons

Dipole and nondipole photoionization of molecular hydrogen

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