A. Verweyen

Resonant 3p photoelectron spectroscopy of free Cu atoms

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.

Valence satellite and 3p photoelectron spectra of atomic Fe and Cu

The 3p photoelectron spectra of atomic Fe and Cu, and the Fe outer-shell satellites have been investigated. The complex multiline structure of the Fe spectra has been resolved using high-resolution electron spectroscopy. The thresholds of the direct 3p photoionization have been determined and are compared with experimental results from photoabsorption measurements and Auger spectra, and with the multiplet structures calculated taking into account intershell and configuration interaction. The stepwise decay of highly excited Fe states into has been verified by the detection of satellite lines with binding energies above the lowest ionization threshold.

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

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.

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

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.

LINEAR DICHROISM IN PHOTO-INDUCED AUGER ELECTRON EMISSION FROM ALIGNED CR ATOMS

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 in the core-resonant photoelectron spectra of laser-aligned Cr atoms

The linear dichroism in the intensity of the electrons (LD) emitted by laser-aligned ground state and excited-state Cr atoms has been exploited in order to characterize the prominent 3p core resonances. The experimental spectra are compared to calculations based on theoretical partial cross sections.

Combining high-resolution photoelectron spectroscopy and laser polarization for a study of the 4f and 5p photoionization of atomic thulium

The 4f and 5p subvalence photoionization of atomic Tm has been investigated by combining high-resolution photoelectron spectroscopy and dichroism measurements of the laser-polarized atoms. The experimental results are compared to Hartree–Fock calculations. The Tm 5p photoelectron spectrum is dominated by spin–orbit splitting whereas mixing of the final ionic states strongly influences the Tm 4f photoionization. Intermediate coupling is appropriate for the explanation of the complex Tm 4f multiplet structure, though some lines are well described within LS coupling. This suggests a partial breakdown of the LS-coupling approximation for Tm 4f photoionization. In comparison to the corresponding spectra of Eu the Tm spectra are much less affected by the admixture of 6s5d and 5d2 valence electron configurations.

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

Abstract The 4 f photoionization of Eu atoms oriented in the ground state was investigated by means of photoelectron spectroscopy with linearly polarized vacuum ultraviolet radiation. Strong magnetic dichroism could be observed for atoms oriented parallel/antiparallel to the VUV photon beam by optical pumping with circularly polarized laser radiation. The magnetic dichroism of the free atoms, well described within the general theory of photoelectron angular distribution, displays the same characteristic features as the CMD of thin Eu films on a ferromagnetic Gd substrate.

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

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.

High resolution spectroscopy of 2p6→2p53d resonantly excited atomic Ca

Abstract Free calcium atoms were excited in the energy region about 10 eV below the 2p thresholds. For the excitation, synchrotron radiation from the high resolution undulator beamline BW3 (HASYLAB, Hamburg) equipped with a SX-700 monochromator was used. The excited atoms were studied by means of ion as well as electron spectroscopy. Two lines could be resolved within one of the two dominating features of the 2 p →3 d resonance. Resonance enhanced 3 p −1 photoelectron spectra resolving the 2 P 1 2 and 2 P 3 2 lines are presented.