A Verweyen

Universität Hamburg

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B. Sonntag

Universität Hamburg

P. Zimmermann

University Hospital Leipzig

K. Godehusen

Helmholtz-Zentrum Berlin für Materialien und Energie

Philippe Wernet

Uppsala University

A. von dem Borne

University of Amsterdam

Ch. Gerth

Deutsches Elektronen-Synchrotron DESY

Pieter Glatzel

European Synchrotron Radiation Facility

Th. Dohrmann

Universität Hamburg

B. Obst

FZI Research Center for Information Technology

Joachim Schulz

European X-Ray Free-Electron Laser

Cooperative Institutions

Universität Hamburg

Technische Universität Berlin

Dublin City University

Deutsches Elektronen-Synchrotron DESY

Queen's University Belfast

European X-Ray Free-Electron Laser

University of Amsterdam

Université Paris-Sud

Lomonosov Moscow State University

Georgia State University

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Sum rules and spectral patterns of dichroism in inner-shell photoelectron spectra

Physical Review A (1999)

A Verweyen Alexei N. Grum-Grzhimailo N M Kabachnik

A theoretical description of dichroism in the photoelectron spectra of atoms polarized in different directions is presented. It is based on the general expression for the photoelectron angular distribution written in $\mathrm{LSJ}$ approximation. We show that, for photon energies far above threshold, the spectral distribution of dichroism in the photoelectron spectrum in most cases does not depend on the photoionization dynamics; for atoms with S symmetry, simple spectral patterns are obtained. Useful sum rules are given for the dichroism integrated over groups of photoelectron multiplet lines. Recent experimental data on magnetic dichroism and linear dichroism in the nonresonant inner-shell spectra of Cr $(3p$ shell), Eu $(4f$ shell), and Fe $(3p$ shell) are analyzed. An outlook is given on the dichroism in the region of autoionization resonances.

Dichroism

Linear dichroism

Autoionization

Multiplet

10.1103/physreva.60.2076

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Citations (35)

Resonant inner-shell photoelectron spectra of ground-state and laser-excited Cr atoms

Journal of Physics B Atomic Molecular and Optical Physics (1996)

Th. Dohrmann A. von dem Borne A Verweyen B. Sonntag Marco Wedowski

Photoelectron spectra and partial cross sections of ground-state and laser-excited Cr atoms in the range of the excitations are presented. The experimental spectra are compared with results obtained by calculations within the spin-polarized random-phase approximation with exchange (SP RPAE), in which the dynamic relaxation upon core hole creation is taken into account.

10.1088/0953-4075/29/20/018

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Citations (24)

Determination of Ca 2p ionization thresholds by high-resolution photoelectron spectroscopy

Journal of Physics B Atomic Molecular and Optical Physics (1998)

Philippe Wernet Pieter Glatzel A Verweyen B. Sonntag B. Obst

The energies of the closely spaced Ca 2p thresholds have been determined by crossing an atomic beam of calcium with the monochromatized synchrotron radiation from the high-resolution undulator beamline SX 700 - BW3 at HASYLAB and analysing the kinetic energy of the outgoing photoelectrons with a high-resolution SCIENTA SES 200 electron analyser. The experimental results are compared to the predictions of different theoretical approaches and the strong influence of electron correlation in the core ionized state is demonstrated.

Photoelectric effect

Undulator

Analyser

Electron spectroscopy

10.1088/0953-4075/31/7/002

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Citations (5)

Linear dichroism in photo-induced Auger electron emission from aligned Cr atoms

Journal of Physics B Atomic Molecular and Optical Physics (1998)

A. von dem Borne Th. Dohrmann A Verweyen B. Sonntag K. Godehusen

We report the first observation of linear dichroism in the photo-induced Auger electron emission from aligned atoms. The linear dichroism in the Cr Auger spectrum shows striking similarity to the corresponding linear dichroism in the 3p photoelectron spectrum. The theoretical analysis presented here proves that the linear dichroism in the Auger spectrum depends on the same dynamical parameters as the linear dichroism in direct photoionization.

Linear dichroism

Dichroism

Vibrational Circular Dichroism

Auger electron spectroscopy

10.1088/0953-4075/31/2/002

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Citations (7)

Suppression of the low-spin multiplet components in the3pphotoelectron spectra of atomic and solid3dmetals

Physical Review A (2000)

A. von dem Borne Robert L. Johnson B. Sonntag M. Talkenberg A Verweyen

The $3p$ photoelectron spectra of Cr, Mn, Fe, and Co atoms have been studied experimentally and theoretically. The $3p$-$3d$ interaction in the final ionic state gives rise to an $\mathrm{LS}$ multiplet structure spanning a binding-energy range of around 20 eV. The prominent high-spin components at low binding energies contrast with the broad and weak low-spin components at high binding energies. Term-dependent lifetime broadening by super-Coster-Kronig decays is the main cause of the almost complete suppression of the latter lines. The corresponding $3p$ photoelectron spectra of the metals display only a single broad asymmetric line. The influence of correlation on the $3p$ photoelectron spectra is shown to be less dramatic than in the case of the better known $3s$ photoelectron spectra. We show that, while the peculiarities in the $3s$ spectrum are caused by configuration interaction, the single-configuration approximation already provides the clue to the interpretation of the $3p$ spectrum.

Multiplet

Line (geometry)

10.1103/physreva.62.052703

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Citations (55)

Combined experiments on XUV dichroism of polarized metal atoms

A Verweyen

The 4f photoionization of polarized Europium atoms in an atomic beam was studied by electron spectroscopy. The atoms were prepared in the oriented or aligned ground state by optical pumping with circularly or linearly polarized laser radiation. Monochromatized synchrotron radiation of the electron storage ring BESSY (Berlin) was used to ionize the atoms well above the 5p thresholds. A strong dichroism in the 4f main line was observed for oriented as well as for aligned Eu atoms. The shape of the dichroism in the photoelectron spectrum could be explained very well within an LS-coupling model. Detailed information on the amplitudes and phases of the dipole matrix elements, and therefore on the dynamics of photoionization, could be extracted by normalization to the photoionization cross section. Strong configuration interaction in the final state, which was confirmed by independent high-resolution photoelectron spectroscopy, established the necessity to take into account the manybody aspect of atomic photoionization. The dichroism in the atomic spectrum closely agrees with the corresponding circular magnetic dichroism in the 4f spectrum of a thin film of Eu on Gd, which emphasizes the atomic character of dichroism in the 4f photoionization of bound Eu and Gd atoms.

Dichroism

Linear dichroism

Source

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Magnetic dichroism in the 4f photoelectron spectra of free Eu atoms: Experimental proof of the atomic character of thin film Eu–Gd MCD

Journal of Electron Spectroscopy and Related Phenomena (1999)

A Verweyen Philippe Wernet B. Sonntag K. Godehusen P. Zimmermann

Linear dichroism

Dichroism

10.1016/s0368-2048(98)00443-5

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Citations (8)

Breakdown of the three-parameter model for the dichroism in the 4f photoelectron spectrum of laser-aligned Eu atoms

Journal of Physics B Atomic Molecular and Optical Physics (1999)

A Verweyen Philippe Wernet Joachim Schulz B. Sonntag M. Martins

The dichroism in the 4f photoelectron spectra of laser-aligned Eu atoms has been determined with linearly polarized vacuum ultraviolet radiation. The experimental results disagree with the prediction of the three-parameter model based on the absolute magnitude and relative phase of the 4f d, g transition matrix elements. It is suggested that strong configuration interactions, confirmed in high-resolution photoelectron spectra, are the cause of the breakdown of the three-parameter model.

Ultraviolet

10.1088/0953-4075/32/16/307

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Citations (9)

Resonant 3p photoelectron spectroscopy of free Cu atoms

Journal of Physics B Atomic Molecular and Optical Physics (2000)

A Verweyen Philippe Wernet Pieter Glatzel B. Sonntag Ch. Gerth

Excitation and decay of the Cu 3p core resonances have been studied by resonant photoelectron spectroscopy. In comparison with theoretical predictions the importance of electron correlation for the resonance energies and line shapes is verified.

Line (geometry)

Electron spectroscopy

10.1088/0953-4075/33/8/307

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Citations (7)

Photoionization of atomic copper in the region of the3pinner-shell thresholds

Physical Review A (1998)

A Verweyen David Donnelly A Hibbert K L Bell

Vacuum ultraviolet photoionization of atomic copper is studied within nonrelativistic R-matrix theory. Special care is taken to provide an adequate description of the Cu II target states by means of a configuration interaction method. Using the fact that the R-matrix method allows for an estimate of the relative importance of the $l=0$ and $l=2$ channels in the $3\stackrel{\ensuremath{\rightarrow}}{p}n,\ensuremath{\varepsilon}l$ photoionization, a complete assignment of the experimental photoabsorption spectrum obtained by Bruhn et al. [J. Phys. B 12, 203 (1979)] is provided. Finally, the coupling of the $3p$ excitations to the dominating spectator decay channels is considered with respect to the resonance line shapes.

R-matrix

Matrix (chemical analysis)

Ultraviolet

10.1103/physreva.58.3338

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Citations (2)