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Krypton atoms were excited by photons in the energy range from the threshold for photoionization of the 3d-electrons up to 120 eV, and the fluorescence radiation in the spectral range from 780 to 965 A was observed and analyzed. Cross sections for the population of excited states in KrIII with at least one 4s-hole resulting from an Auger transition as the first decay step and for KrII satellites were determined. The energy dependence of the 3d-ionization cross section in the 3d 5 2 -and the 3d 3 2 -threshold range was derived from the experimental data. The cross sections for production of KrII states were found to follow the energy dependence of the 3d-cross sections.

For the electronic- and charge-state specific determination of VUV?VIS fluorescence emission cross sections after collisions between heavy ions and neutral gases or electrons a fluorescence spectrometer for the VUV?VIS spectral range is planned. Tentative experiments showed that signal rates after collisions between Xe atoms and ions are high enough to allow efficient experiments.

Absolute Kr 4s-electron photoionization cross sections as a function of the exciting-photon energy were measured by photon-induced fluorescence spectroscopy (PIFS) at improved primary-energy resolution. The cross sections were determined from threshold to 33.5 eV and to 90 eV with primary-photon bandwidths of 25 meV and 50 meV, respectively. The measurements were compared with experimental data and selected theoretical calculations for the direct Kr 4s-electron photoionization cross sections.

The Kr 4s-electron photoionization cross section as a function of the exciting-photon energy in the range between 30 eV and 90 eV was calculated using the configuration interaction (CI) technique in intermediate coupling. In the calculations the 4p spin-orbital interaction and corrections due to higher orders of perturbation theory (the so-called Coulomb interaction correlational decrease) were considered. Energies of Kr II states were calculated and agree with spectroscopic data within less than 10 meV. For some of the Kr II states new assignments were suggested on the basis of the largest component among the calculated CI wavefunctions.

Regularly arranged magnetic out-of-plane patterns in continuous and flat films are promising for applications in data storage technology (bit patterned media) or transport of individual magnetic particles. Whereas topographic magnetic structures are fabricated by standard lithographical techniques, the fabrication of regularly arranged artificial domains in topographically flat films is difficult, since the free energy minimization determines the existence, shape, and regularity of domains. Here we show that keV He + ion bombardment of Au/Co/Au layer systems through a colloidal mask of hexagonally arranged spherical polystyrene beads enables magnetic patterning of regularly arranged cylindrical magnetic monodomains with out-of-plane magnetization embedded in a ferromagnetic matrix with easy-plane anisotropy. This colloidal domain lithography creates artificial domains via periodic lateral anisotropy variations induced by periodic defect density modulations. Magnetization reversal of the layer system observed by magnetic force microscopy shows individual disc switching indicating monodomain states. (Some figures in this article are in colour only in the electronic version)

We discuss the recent progress in the development of the single center (SC) method for computation of highly-delocalized discrete and partial photoelectron wave continuous functions of molecules. Basic equations of the SC method are presented, and an efficient scheme for the numerical solution of a system of coupled Hartree–Fock equations for a photoelectron is described. Several illustrative applications of the method to photoionization and electronic excitation processes in diatomic molecules are considered. Thereby, we demonstrate its potential for theoretically studying angularly resolved molecular photoionization processes.

The D^1\Pi_u - X^1\Sigma_g^+ absorption system of molecular deuterium has been re-investigated using the VUV Fourier -Transform (FT) spectrometer at the DESIRS beamline of the synchrotron SOLEIL and photon-induced fluorescence spectrometry (PIFS) using the 10 m normal incidence monochromator at the synchrotron BESSY II. Using the FT spectrometer absorption spectra in the range 72 - 82 nm were recorded in quasi static gas at 100 K and in a free flowing jet at a spectroscopic resolution of 0.50 and 0.20 cm^{-1} respectively . The narrow Q-branch transitions, probing states of \Pi^- symmetry, were observed up to vibrational level v = 22. The states of \Pi^+ symmetry, known to be broadened due to predissociation and giving rise to asymmetric Beutler-Fano resonances, were studied up to v = 18. The 10 m normal incidence beamline setup at BESSY II was used to simultaneously record absorption, dissociation, ionization and fluorescence decay channels from which information on the line intensities, predissociated widths, and Fano q-parameters were extracted. R-branch transitions were observed up to v = 23 for J = 1-3 as well as several transitions for J = 4 and 5 up to v = 22 and 18 respectively. The Q-branch transitions are found to weakly predissociate and were observed from v = 8 to the final vibrational level of the state v = 23. The spectroscopic study is supported by two theoretical frameworks. Results on the \Pi^- symmetry states are compared to ab initio multi-channel-quantum defect theory (MQDT) calculations, demonstrating that these calculations are accurate to within 0.5 cm^-1., Comment: 16 pages, 10 figures, 2 tables, supplemental material with an additional table

Absolute cross sections for the transitions of the Kr atom into the 4s1 and 4p4nl states of the Kr+ ion were measured in the 4s-electron threshold region by photon-induced fluorescence spectroscopy (PIFS). The cross sections for the transitions of the Kr atom into the 4s1 and 4p4nl states were also calculated, as well as the 4p4nln'l' doubly excited states, in the frame of LS-coupling many-body technique. The cross sections of the doubly-excited atomic states were used to illustrate the pronounced contributions of the latter to the photoionization process, evident from the measurements. The comparison of theory and experiment led to conclusions about the origin of the main features observed in the experiment.

Cross sections for double photoionization of the Ne L shell into the 2s2p5 3P0 and 1P0 and the 2s02p6 1Se states were measured for energies from threshold up to 150 eV, using photon induced fluorescence spectroscopy. Both 2s2p5 channels were observed with comparable magnitude in contradiction to a propensity rule based on the Wannier-Peterkop-Rau theory. A comparison of the summed 3P0 and 1P0 cross sections with MBPT calculations results in a deviation of 50%.

Perturbation theory in the lowest non-vanishing order in interelectron interaction has been applied to the theoretical investigation of double-ionization decays of resonantly excited single-electron states. The formulae for the transition probabilities were derived in the LS coupling scheme, and the orbital angular momentum and spin selection rules were obtained. In addition to the formulae, which are exact in this order, three approximate expressions, which correspond to illustrative model mechanisms of the transition, were derived as limiting cases of the exact ones. Numerical results were obtained for the decay of the resonantly excited Kr I 3d-15p(1P) state which demonstrated quite clearly the important role of the interelectron interaction in double-ionization processes. On the other hand, the results obtained show that low-energy electrons can appear in the photoelectron spectrum below the ionisation threshold of the 3d shell.

A new type of many-electron radiative transitions involving three electrons is predicted. The results of the authors' investigation by many-body perturbation theory are presented. Spectral lines observed in the wavelength range of 37.5 to 54.0 nm by means of photon-induced fluorescence spectroscopy (PIFS) following the excitation of the Kr I 3d-1np resonances are reported and compared with the predictions.

Photon-induced fluorescence spectroscopy (PIFS) using monochromatized synchrotron radiation for exciting the sample selectively and a fluorescence spectrometer with a position-sensitive photon detector for recording its fluorescence spectrum is a very powerful experimental technique especially for the investigation of atomic and molecular photoionization and photodissociation. To reduce the contributions of higher harmonics of the undulator radiation which are also transmitted through the primary monochromator a very compact He absorber was developed. With a He pressure of 30 mbar in the differentially pumped gas cell of the absorber the fraction of the third harmonic of the undulator transmitted through the monochromator was reduced by a factor of 175 for an exciting-photon energy of the first order of 24.18 eV.

Parameters $\ensuremath{\beta}1$ and $\ensuremath{\beta}2$ describing the angular distribution of circularly polarized fluorescence photons emitted by randomly oriented diatomic molecules excited by circularly polarized radiation are derived. We prove theoretically that measuring these parameters allows a partial-wave analysis of the emitted photoelectrons in the case of closed-shell diatomic molecules. The determination of the relative partial cross sections for emission of the $\ensuremath{\varepsilon}\ensuremath{\sigma}$, $\ensuremath{\varepsilon}\ensuremath{\pi}$, and $\ensuremath{\varepsilon}\ensuremath{\delta}$ photoelectrons is of fundamental importance for a sensitive test of corresponding calculations.

Defined perpendicular anisotropy gradients in the Co sublayers of a $[\mathrm{Co}(0.6\text{ }\text{ }\mathrm{nm})/\mathrm{Au}(2\text{ }\text{ }\mathrm{nm}){]}_{3}$ sputter-deposited multilayer have been introduced by light ion bombardment through a wedged Au stopper layer. Within such a layer system, domain walls between up- and down-magnetized areas are controllably movable by an external perpendicular homogeneous magnetic field. This method and layer system is very promising for a controlled magnetic particle transport within the stray fields of the moving domain walls.

Quantum mechanical interference between different pathways in inner-shell resonance excitation-deexcitation spectra is a realization of a double-slit experiment on the atomic scale. If the intermediate inner-shell resonances are of different symmetries, this interference is symmetry forbidden in the solid-angle-averaged or magic-angle-recorded deexcitation spectra. It has, however, been suggested that interference may by observable in off-magic-angle-recorded spectra. Here, we prove this interference in angularly resolved deexcitation spectra of the $2{\ensuremath{\sigma}}^{\ensuremath{-}1}2{\ensuremath{\pi}}^{2}(^{2}\ensuremath{\Delta},^{2}\ensuremath{\Sigma}^{\ifmmode\pm\else\textpm\fi{}})$ resonances of ${\mathrm{N}}^{*}\mathrm{O}$ by a quantitative comparison between ab initio calculations and experiment.

The absolute cross sections for the competing decay channels fluorescence, dissociation, and ionization of photoexcited long-lived superexcited H(2) molecular levels have been measured from the ionization threshold of H(2) up to the H(1s)+H(n=3) dissociation limit. The total and partial natural widths of these levels have been determined. Good agreement is found with first principles calculations carried out by multichannel quantum defect theory. The calculations reproduce the balance between the competing decay processes as well as its substantial level-to-level evolution.

The absolute cross sections for the competing decay-channel fluorescence, dissociation, and ionization of photoexcited long-lived superexcited ${\mathrm{H}}_{2}$ molecular levels have been measured from the ionization threshold of ${\mathrm{H}}_{2}$ up to the H($1s$) $+$ H($n=3$) dissociation limit. The total and partial natural widths of these levels have been determined. Good agreement is found with first principles calculations carried out with the multichannel quantum defect theory for excited levels of ${}^{1}{\ensuremath{\Pi}}_{u}^{\ensuremath{-}}$ symmetry, which represent $70%$ of the levels studied experimentally. The calculations reproduce the balance between the competing decay processes as well as its substantial evolution from level to level.

The exchange bias effect in ferromagnetic/antiferromagnetic sandwich structures is generally believed to be sensitive on the interface exchange interaction, the magnetization, and the thickness of the ferromagnetic layer. Also the interface structure plays a crucial role. We show that, by irradiating samples with He ions, we can manipulate the exchange bias field in a controlled manner. Depending on the dose (1014–1017 ions/cm2) and the acceleration voltage (10–35 kV) of the ions, the shift of the hysteresis can be reduced or even fully suppressed. Potential applications of this effect for magnetic patterning on the nanoscale will be discussed.

FeNi/FeMn exchange bias samples with a large exchange bias field at room temperature have been prepared on a Cu buffer layer. Upon irradiation with He ions, both the exchange bias field and the coercive field are modified. For low ion doses the exchange bias field is enhanced by nearly a factor of 2. Above a threshold dose of 0.3olsi 10 15 ions/cm 2 , the exchange bias field decreases continuously as the ion dose increases. The ob-served modifications are explained in terms of defect creation acting as pinning sites for domain walls and atomic intermixing.

Angular distributions of the ${\text{CO}}^{+}(A\text{ }^{2}\ensuremath{\Pi})$ photoelectrons and of the ${\text{CO}}^{+}(A\text{ }^{2}\ensuremath{\Pi}\ensuremath{\rightarrow}X\text{ }{^{2}\ensuremath{\Sigma}}^{+})$ fluorescence are computed in the vicinity of the $1{s}^{\ensuremath{-}1}{\ensuremath{\pi}}^{\ensuremath{\ast}}$ resonant excitation of the ${\text{C}}^{\ensuremath{\ast}}\text{O}$ molecule. In the calculations, lifetime vibrational interference and the direct transition amplitude for population of the $A\text{ }^{2}\ensuremath{\Pi}({v}^{\ensuremath{'}})$ states were taken into account ab initio. The weak direct photoionization channel induces broad exciting-photon energy range dispersions of the angular distribution parameters ${\ensuremath{\beta}}_{A}^{e}(\ensuremath{\omega})$ and $\ensuremath{\beta}{2}_{A}^{X}(\ensuremath{\omega})$, and the nuclear vibrational motion causes variations of the computed parameters across the positions of the ${\text{C}}^{\ensuremath{\ast}}\text{O}({v}_{r})$ vibronic states. Present calculations are in good agreement with available vibrationally and angularly resolved resonant Auger spectra. Theoretical $\ensuremath{\beta}{2}_{A}^{X}(\ensuremath{\omega})$ parameters are in agreement with the experimental results from the polarization analysis of the ${\text{CO}}^{+}(A\text{\ensuremath{-}}X)$ fluorescence induced by linearly polarized synchrotron radiation.

Physical review / B 80, 205323 (2009). doi:10.1103/PhysRevB.80.205323, Published by APS, College Park, Md.

A combination of experimental techniques, e.g. vector-MOKE magnetometry, Kerr microscopy and polarized neutron reflectometry, was applied to study the field induced evolution of the magnetization distribution over a periodic pattern of alternating exchange bias stripes. The lateral structure is imprinted into a continuous ferromagnetic/antiferromagnetic exchange-bias bi-layer via laterally selective exposure to He-ion irradiation in an applied field. This creates an alternating frozen-in interfacial exchange bias field competing with the external field in the course of the re-magnetization. It was found that in a magnetic field applied at an angle with respect to the exchange bias axis parallel to the stripes the re-magnetization process proceeds via a variety of different stages. They include coherent rotation of magnetization towards the exchange bias axis, precipitation of small random (ripple) domains, formation of a stripe-like alternation of the magnetization, and development of a state in which the magnetization forms large hyper-domains comprising a number of stripes. Each of those magnetic states is quantitatively characterized via the comprehensive analysis of data on specular and off-specular polarized neutron reflectivity. The results are discussed within a phenomenological model containing a few parameters which can readily be controlled by designing systems with a desired configuration of magnetic moments of micro- and nano-elements., 11 pages, 7 figures

The manipulation of magnetic particles at the nanometer scale is of great interest for applications in biotechnology. In this work the self-assembly of 12 nm Co nanocrystallites under the influence of magnetic strayfields originating from a magnetically patterned 3 nm thick CoFe layer has been investigated. The magnetic patterning has been carried out by bombardment with 10 keV He ions in an external magnetic field. A controllable accumulation of magnetic nanoparticles has been found at areas of the sample with a head to head orientation of the local magnetization. The force generated by the strayfield of Neel walls without head to head orientation of the magnetization is about ten times weaker and turned out to be just strong enough to attract a relatively small number of nanocrystals. Furthermore, it has been shown that the choice of the procedure to bring the particle solution onto the magnetically patterned sample determines the successful generation of particle arrangements and can be used to tune the number of particles and their coordination within the strayfield. (c) 2007 American Institute of Physics.

The angular correlation functions of a pair of Lyman-α photons in the photodissociation of H2 are measured more precisely than in the early experiments [Nakanishi et. al., Phys. Rev. A. 90, 043405(2014)]. The linearly polarized light is used to excite the photodissociation via the doubly excited Q2 1Πu(1) state.

We present emission cross section functions for Lyman series fluorescence emission after photoexcitation of water molecules with monochromatized synchrotron radiation as function of the exciting-photon energy. Both the valence and inner-shell excitation energy range of the water molecule are covered. The results are compared to literature and contribute to complete the model of dissociative relaxation dynamics of excited small molecules.

We have measured the emission spectrum of gaseous hydrogen molecules in the far ultraviolet spectral range over the large interval of excitation energies between 11 eV and 17 eV. This regime is governed by singly excited electronic states below the ionization threshold. While these features have been already investigated separately in the past, the completeness of the present measurements allows a very intuitive representation of the participating molecular effects and their respective correlations. It also contains the first complete investigation of the Condon diffraction bands visible for hydrogen through transitions into the ground state continuum.

Magnetization reversal of perpendicular anisotropy [Co/Au] multilayers patterned into micrometer wide stripes with a coercivity gradient along the stripes was investigated with polar magnetooptical Kerr effect microscopy. 1 mm-long stripes were bombarded with He+ ions of 10 keV energy to induce the gradient. It was shown that short pulses of a magnetic field applied perpendicularly to the sample plane move domain walls between up- and down-magnetized areas in a direction of regions with higher coercivities.

Tailored parallel-stripe magnetic domains with antiparallel magnetizations in adjacent domains along the long stripe axis have been fabricated in an IrMn/CoFe Exchange Bias thin film system by 10 keV He+-ion bombardment induced magnetic patterning. Domain walls between these domains are of Neel type and asymmetric as they separate domains of different anisotropies. X-ray magnetic circular dichroism asymmetry images were obtained by x-ray photoelectron emission microscopy at the Co/Fe L3 edges at the synchrotron radiation source BESSY II. They revealed Neel-wall tail widths of 1 μm in agreement with the results of a model that was modified in order to describe such walls. Similarly obtained domain core widths show a discrepancy to values estimated from the model, but could be explained by experimental broadening. The rotation senses in adjacent walls were determined, yielding unwinding domain walls with non-interacting walls in this layer system.

In magnetic bilayer systems consisting of a ferromagnet and an antiferromagnet the strength and direction of the exchange bias coupling can be set by ion bombardment in an external magnetic field. Magnetic nanostructures with a laterally varying exchange bias direction can be produced by local ion bombardment (ion bombardment induced magnetic patterning). We have investigated the thermal stability of these magnetic nanostructures by in situ x-ray photoemission electron microscopy while heating the samples above their blocking temperature. The investigations have been done at a 10.4 mu mx10.4 mu m large checkered pattern with a minimum size of the magnetic patterns of 800 nmx800 nm on a field cooled MnIr/CoFe stack and a pattern with 1.6 mu m wide lines with a periodicity of 5 mu m on an as-prepared MnIr/Co stack. The temperature dependence of the magnetization pattern can be explained by the temperature dependence of the exchange bias interaction, the exchange interaction energy, and the stray field energy. No substantial change of the thermal stability of magnetic patterns in remanence by the ion bombardment was found.

We have investigated the magnetization arrangement in an in-plane stripe pattern with alternating exchange-bias domains. The stripe pattern was produced by ion bombardment induced magnetic patterning, which changed locally the exchange-bias direction at the ferromagnet/antiferromagnet interface, but not the magnetic or antiferromagnetic properties of the Co70Fe30 and Mn83Ir17 layers, respectively. For the analysis of the magnetic domain structure evolution along the hysteresis loop we used a combination of experimental techniques: magneto-optical Kerr effect, Kerr microscopy, polarized neutron reflectometry, and off-specular scattering of polarized neutrons with polarization analysis. Instead of a perfect antiparallel alignment we found that the magnetization in neighboring stripes is periodically canted with respect to the stripe axis so that the net magnetization of the ferromagnetic film turns almost perpendicular to the stripes. At the same time the projection of the magnetization vector onto the stripe axis has a periodically alternating sign. The experimental observations are explained and quantitatively described within the frame of a phenomenological model, taking into account interfacial exchange bias, intralayer exchange energy, and uniaxial anisotropy. The model defines conditions which can be used for tailoring nano- and micro-patterned exchange-bias systems with different types of magnetic order.

A local manipulation of the exchange bias coupling between antiferromagnetic and ferromagnetic layers by ion bombardment induced magnetic patterning enables a patterning of the magnetization direction of the ferromagnetic layer without considerable structural changes. We show that a magnetic line grating with alternating antiparallel orientations of the magnetization of the ferromagnetic layer acts as a magnetically switchable reflective grating for soft x-ray radiation. A common rotational direction of the magnetization at all boundaries between bombarded and not bombarded lines is shown by magnetic force microscopy measurements. Scattering at the edges of the bombarded lines might be responsible for the observed interference pattern. (c) 2006 American Institute of Physics.

Dispersed fluorescence excitation functions and the relative total ion yield as a function of the exciting-photon energy in the range between 26.150 eV and 26.400 eV have been measured for Xe after excitation with monochromatized synchrotron radiation with the very narrow bandwidth of 2.5 meV. Fluorescence excitation functions have been simultaneously measured in the VUV and in the visible spectral range to track and identify radiative decay cascades after photoionization into excited XeII states of 5p46p electron configuration. Additionally the angular fluorescence distribution parameter βfl-parameter was experimentally determined for some of the observed fluorescence lines.

Exchange-biased IrMn/CoFe full films are magnetically structured with He-ion bombardment into stripes with antiparallel-aligned loop shift. The patterning results in a two-step magnetization loop corresponding to two regions of oppositely aligned exchange bias. The longitudinal magnetization reversal through head-on domain-wall motion and partial penetration of magnetization from neighboring strips is highly asymmetric involving ripplelike domain structures and incoherent rotation of magnetization. In addition, Neel-wall-like structures with a preferred sense of rotation are formed at the edges of the strips. Along the transverse direction the reversal is dominated by the switching of the magnetic border structures between the strips. Complicated domain patterns are generated under other external field angles. (c) 2005 American Institute of Physics.

The influence of a postannealing procedure on the transport properties of magnetic tunnel junctions with ion-bombardment-manipulated exchange bias is investigated. The controlled manipulation of the direction of the exchange bias field in magnetic tunnel junctions by He ion bombardment usually is accompanied by a reduction of the tunneling magnetoresistance and an increase in the resistance. Here, we demonstrate that it is possible to reduce these negative effects of the ion bombardment considerably by postannealing without a magnetic field. For optimized combinations of ion dose and postannealing temperature, the tunneling magnetoresistance recovers completely (>50% resistance change) while the exchange bias direction set by the ion bombardement is preserved. (C) 2005 American Institute of Physics.

The excitation function of the dissociative photoionization excitation (DIE) of N2 has been measured with the detection technique of coincidence between photoion and fluorescence-photon using extreme-uv synchrotron radiation (SR) as an excitation source in the energy region of 35 – 65 eV and the detection direction parallel and perpendicular to the polarization vector of SR. The coincidence spectra obtained in this energy region show at least two qualitatively different structures originating from two different DIE processes. The major components of the DIE in the present energy region is ascribed to the dissociation of the 2σg−1 2∑g+ state which is strongly coupled with correlation states in the 2∑g+ symmetry.

The influence of He ion bombardment on the structural and magnetic interface properties of a polycrystalline Mn83Ir17/Co antiferromagnet-ferromagnet bilayer system is investigated. For annealed as well as for not annealed samples an exchange bias field of up to 200 Oe is induced by the ion bombardment for doses up to 5x10(14) ions/cm(2). The x-ray absorption and the x-ray magnetic circular dichroism of Co and Mn is not significantly altered by this ion dose. For higher doses the exchange bias field is strongly reduced and accompanied by an increase of the ratio of the Mn to Co x-ray absorption intensities and a reduction of the Co x-ray magnetic circular dichroism signal. A model with a Gaussian-like intermixing zone at the AF/FM interface is developed to account for the observed changes of the x-ray absorption spectra.

A short review of theoretical and experimental papers devoted to the investigation of the alignment, A20, and orientation, O10, of ions after the decay of atomic resonances is presented. Special attention is paid to the dependence of A20 and O10 on the exciting‐photon energy. The possible ways for improving the theoretical description of the resonant Auger effect are also discussed.

Magnetic tunnel junctions (Mn83Ir17/Co70Fe30/AlOx/Ni80Fe20) were bombarded by 10-20 keV He+ ions in an applied magnetic field to manipulate the exchange bias of the magnetically hard electrode. The tunneling magnetoresistance of the bombarded junctions is up to 37.8% for ion doses high enough to ensure a well defined exchange bias. This should allow the preparation of high quality tunnel junctions with magnetic micropatterned hard electrodes. For very high ion doses the tunneling magnetoresistance starts to decrease, whereas the area resistance product increases. Possible explanations based on structural alterations of the tunneling barrier are discussed. (C) 2003 American Institute of Physics.

Absolute Kr 4s-electron photoionization cross sections as a function of the exciting-photon energy between 30 and 90 eV were measured by photon-induced fluorescence spectroscopy (PIFS). The measurements were compared with available experimental data and theoretical calculations.

Rare gas valence shell satellites excited by linearly polarized synchrotron radiation are produced exclusively through electron correlations. In the near threshold range they show a strong enhancement through the autoionization of doubly excited Rydberg states. Studying the fluorescence decay of the excited photoions we derived the alignment parameter A20, which depends on the dynamics of the decay process. Here we report on the population of the Ne+ 2p4 2PJ and 4PJ finstructure states. While the 2PJ states show interference between direct population and autoionization, the 4PJ states to the contrary, are populated only through autoionization. This is a clear indication for singlet/triplet mixing of the more closely investigated Ne 2p4(3P) 3p 2P3/2,1/2-ns, nd-Rydberg-states, since the population of the 4PJ-states is forbidden in LS-coupling. Corresponding autoionization processes were studied for the heavier rare gases in order to reveal systematic features.

Using controlled ion bombardment, the contribution of interface and bulk antiferromagnetic spins to exchange bias (EB) is investigated. Several sets of ferromagnetic (FM)/antiferromagnetic (AFM) (Ni/FeF2) bilayers capped with a nonmagnetic and inert Au layer of varying thickness were grown simultaneously. He-ion bombardment was employed to selectively create defects in the EB structure at the FM/AFM interface or in the AFM bulk. Numerical simulations provide the depth profile of the ion damage. Quantitative structural and magnetic characterizations were compared before and after the bombardment revealing the relationship between interfacial and bulk located defects. These studies show that the creation of defects in the bulk of the antiferromagnet crucially affects the magnitude of EB.

The magneto-optic surface plasmon resonance in transverse geometry of glass/Au/IrMn/Co/Au/dielectric exchange biased thin film systems has been studied as a function of the Au-cap layer thickness for the dielectric air and water. The results show that it is possible to achieve either an optimum steepness of the reflectivity as compared to a glass/Au/dielectric layer system or to maximize the magneto-optic activity. As the Au-cap layer thickness is increased, the magneto-optic activity is reduced whereas the steepness of the reflectivity in the range of the resonance is raised. The width of the reflectivity curves and the magneto-optic signals is broadened for thin Au-capping layers.

The radiationless decay of the Xe N4, 5 levels is investigated theoretically. The strong influence of the giant resonance in the 5s5p5(1P)ef channel on the partial and total Auger widths via the interchannel mixing is revealed. The computed widths of the N4 and N5 levels, equal to 105.9 and 109.6 meV, respectively, are in excellent agreement with the measured values 104(3) and 111(3) meV (Jurvansuu et al 2001 Phys. Rev. A 64 012502). The shape of the computed N4, 5OO Auger spectrum is in good agreement with the measured one. Interchannel interaction reduces the probability of the 5p5p − 4deg Auger decay by more than an order of magnitude. This conclusion is supported by the good agreement between computed and measured Auger electron angular distribution parameters.

Resonance profiles of spectroscopically resolved radiative transitions from ${(2pnd)}^{1}{P}^{o},$ ${(sp,2n+)}^{1}{P}^{o},$ and $(sp,2n\ensuremath{-}{)}^{1}{P}^{o}$ doubly excited He states with $n=3,\dots{},7$ were investigated. The ${(2p3d)}^{1}{P}^{o}--{(1s3d)}^{1}{D}^{e}--{(1s2p)}^{1}{P}^{o}--{1s}^{2}{}^{1}{S}^{e}$ cascade transitions were observed using photon induced fluorescence spectroscopy in the vacuum ultraviolet and the visible spectral range. The $(2pnd)$ levels populate predominantly ${(1snd)}^{1}D$ levels, while for the $(sp,2n+or\ensuremath{-})$ levels, ${n}^{1}S$ levels are populated as well. The experiments demonstrate that further quantitave branching ratio measurements are needed in order to test matrix elements for radiative transitions from ${\mathrm{He}}^{**}.$

Both the direction and the strength of the exchange bias field ${H}_{\mathrm{eb}}$ of an FeNi/FeMn double layer are manipulated locally by He ion irradiation in an applied magnetic field. The magnitude of ${H}_{\mathrm{eb}}$ is enhanced over its initial value in the low ion dose regime. Above a threshold irradiation dose a reduction and eventually a suppression of ${H}_{\mathrm{eb}}$ is found. The direction of ${H}_{\mathrm{eb}}$ is initialized by the field direction during irradiation. These observations are discussed considering the structural modifications caused by the ion bombardment. The data are well described by a model, which is based on the competition between the enhancement of the exchange bias field strength due to defect creation in the antiferromagnetic layer and the decrease induced by intermixing at the ferromagnet/antiferromagnet interface.

The photoionization of the Ne 2s-electrons was studied from threshold to 1 eV above threshold. The technique of photon-induced fluorescence spectroscopy was applied. Pronounced structures were observed resulting from autoionization of doubly excited atomic states. A threshold cross section of 0.17 Mb was determined.

A method, a material system, and the physics for tailoring artificial magnetic field landscapes on micron and submicron length scales over a topographically flat surface in remanence are presented. KeV-He+ ion bombardment induced magnetic patterning was used for the creation of in-plane magnetized domains in Exchange Bias layer systems. This technology sets defined magnetic domain wall charges between the in-plane magnetic domains by individually set domain properties (magnitude and direction of anisotropy parameters) on both sides of the domain wall. The magnetic surface charge distribution was analyzed by magnetic force microscopy and compared to micromagnetic simulations.

Exchange bias is studied in thin film systems, in which three types of Heusler alloys (Ni2MnSn, Co2MnSn, and Co2FeSi) are in contact with an antiferromagnet. Magnetic exchange interactions between the constituting atoms (i.e., Ni-Mn, Mn-Mn, Co-Mn, and Co-Fe, or Co-Co) differ substantially in these Heusler alloys. We explain the influence of the exchange stiffness A within the Heusler alloys and of the exchange coupling between Heusler alloy and an antiferromagnet in a finite interface volume. Insertion of an ultrathin Co layer at interfaces brings about an enhancement of the exchange bias in Heusler alloy/antiferromagnet layer system.