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The local electronic structure of the metal-active site and the deexcitation pathways of metalloporphyrins are crucial for numerous applications but difficult to access by commonly employed techniques. Here, we applied near-edge X-ray absorption mass spectrometry and quantum-mechanical restricted active space calculations to investigate the electronic structure of the metal-active site of the isolated cobalt(iii) protoporphyrin IX cation (CoPPIX+) and its deexcitation pathways upon resonant absorption at the cobalt L-edge. The experiments were carried out in the gas phase, thus allowing for control over the chemical state and molecular environment of the metalloporphyrin. The obtained mass spectra reveal that resonant excitations of CoPPIX+ at the cobalt L3-edge lead predominantly to the formation of the intact radical dication and doubly charged fragments through losses of charged and neutral side chains from the macrocycle. The comparison between experiment and theory shows that CoPPIX+ is in a 3A2g triplet ground state and that competing excitations to metal-centred non-bonding and antibonding σ* molecular orbitals lead to distinct deexcitation pathways., Near-edge X-ray absorption mass spectrometry (NEXAMS) and restricted active space (RAS) quantum mechanical calculations at the metal L-edge reveal the electronic structure and orbital-specific deexcitation pathways of gas-phase metalloporphyrins.

The F 1s core level photoionization of the ionic molecular radical HF+ has been studied using the photon-ion merged-beams technique at a synchrotron radiation source. Upon analyzing kinetic energy release (KER) dependent photoion yield spectra, complex ultrafast dissociation dynamics of the F 1s core hole excited σ* state can be revealed. By means of configuration-interaction electronic structure calculations of the excited molecular potential energy curves, this complex process can be attributed to a spin-dependent dissociation of the excited σ* biradical state.

The F 1s core level photoionization of the ionic molecular radical HF

The use of synchrotron radiation at DESY witnessed an enormous boost when PETRA III, currently the brightest source for hard X-rays worldwide, commenced operation in 2009. After being extended by t...

Author(s): Muller, A; Martins, M; Kilcoyne, ALD; Phaneuf, RA; Hellhund, J; Borovik, A; Holste, K; Bari, S; Buhr, T; Klumpp, S; Perry-Sassmannshausen, A; Reinwardt, S; Ricz, S; Schubert, K; Schippers, S | Abstract: Photoprocesses of the endohedral fullerene ions Sc3N@C80+ and Sc3N@C80- in the gas phase have been investigated in the photon energy ranges 30-50 eV and 280-420 eV. Single and double ionization as well as single ionization accompanied by the release of a C2 dimer were observed as a function of the photon energy for the positive parent ion and double detachment was measured for the negative parent ion. The emphasis of the experiments was on the specific effects of the encapsulated trimetallic nitride cluster Sc3N on the observed reactions. Clear evidence of photoexcitation near the Sc L edge is obtained with the dominating contributions visible in the one- and two-electron-removal channels. K-vacancy production in the encapsulated central nitrogen atom is seen in the single ionization of Sc3N@C80+ but is much less pronounced in the photoionization-with-fragmentation channel. Comparison of the cross sections near the carbon K edge with the corresponding channels measured previously in the photoionization of Lu3N@C80+ reveal strong similarities. Previously predicted sharp resonance features in the ionization of Sc3N@C80+ ions below the Sc M edge are not confirmed. The experiments are accompanied by quantum-chemistry calculations in the Hartree-Fock approximation and by model calculations employing density functional theory (DFT).

Physical chemistry, chemical physics 21(45), 25415-25424 (2019). doi:10.1039/C9CP04640B, Yields of atomic iodine Iq+ (q Z 2) fragments resulting from photoexcitation and photoionisation of thetarget cations CHxI+ (x = 0–3) have been measured in the photon-energy range 610 eV to 670 eV,which comprises the threshold for iodine 3d ionisation. The measured ion-yield spectra show twostrong and broad resonance features due to the excitation of the 3d3/2,5/2 electrons into ef states similarto atomic iodine. In the 3d pre-edge range, electrons are excited into molecular orbitals consisting ofiodine, carbon, and hydrogen atomic orbitals. These transitions have been identified by comparison withliterature data and by simulations using time-dependent density functional theory (TDDFT) with theKMLYP functional. The ion-yield spectrum for CH3I+ resembles the spectrum of IH+ [Klumpp et al., Phys.Rev. A, 2018, 97, 033401] because the highest occupied molecular orbitals (HOMO) of the H and CH3fragments both contain a single vacancy, only. For the molecular cations with higher number ofvacancies in the valence molecular orbitals CHxI+ (x = 0–2), a stronger hybridisation of the molecularorbitals occurs between the organic fragment and the iodine resulting in a change of bonding from asingle s bond in CH3I+ to a triple bond including two p orbitals in CI+. This is reflected in the resonanceenergies of the observed absorption lines below the iodine 3d excitation threshold., Published by RSC Publ., Cambridge

Author(s): Muller, A; Lindroth, E; Bari, S; Borovik, A; Hillenbrand, PM; Holste, K; Indelicato, P; Kilcoyne, ALD; Klumpp, S; Martins, M; Viefhaus, J; Wilhelm, P; Schippers, S | Abstract: In a joint experimental and theoretical endeavor, photoionization of metastable C4+(1s2sS13) ions via intermediate levels with hollow, double-K-vacancy configurations 2s2p, 2s3p, 2p3s, 2p3d, 2s4p, 2p4s, and 2p4d has been investigated. High-resolution photon-ion merged-beams measurements were carried out with the resolving power reaching up to 25 800 which is sufficient to separate the leading fine-structure components of the 2s2pP3 term. Many-body perturbation theory was employed to determine level-to-level cross sections for K-shell excitation with subsequent autoionization. The resonance energies were calculated with inclusion of electron correlation and radiative contributions. Their uncertainties are estimated to be below ±1 meV. Detailed balance confirms the present photoionization cross-section results by comparison with previous dielectronic-recombination measurements. The high accuracy of the theoretical transition energies together with the present experimental results qualify photoabsorption resonances in heliumlike ions as new, greatly improved energy-reference standards at synchrotron radiation facilities.

The fragmentation pattern of the iodine-containing molecules CH2I2 and CH3I following a strong multiphoton excitation in the vicinity of the iodine 4d giant resonance regime is studied using soft X-ray free electron laser radiation. A strong difference of the charge distribution and the kinetic energy release (KER) for the two molecules is found. The effects can be attributed to charge rearrangement processes induced by the photoexcitation. The difference in the observed distribution for higher charge states of iodine and carbon fragments is consistent with an over-the-barrier model for the charge rearrangement in the dissociating molecules. The KER for singly ionised carbon fragments indicates an ultrafast charge rearrangement before the dissociation starts.

Author(s): Muller, A; Borovik, A; Buhr, T; Hellhund, J; Holste, K; Kilcoyne, ALD; Klumpp, S; Martins, M; Ricz, S; Viefhaus, J; Schippers, S | Abstract: Single, double, and triple ionization of the C+ ion by a single photon have been investigated in the energy range 286 to 326 eV around the K-shell single-ionization threshold at an unprecedented level of detail. At energy resolutions as low as 12 meV, corresponding to a resolving power of 24 000, natural linewidths of the most prominent resonances could be determined. From the measurement of absolute cross sections, oscillator strengths, Einstein coefficients, multielectron Auger decay rates, and other transition parameters of the main K-shell excitation and decay processes are derived. The cross sections are compared to results of previous theoretical calculations. Mixed levels of agreement are found despite the relatively simple atomic structure of the C+ ion with only five electrons. This paper is a followup to a previous Letter [A. Muller, Phys. Rev. Lett. 114, 013002 (2015)PRLTAO0031-900710.1103/PhysRevLett.114.013002].

The Photon-Ion Spectrometer at PETRA III - in short, PIPE - is a permanently installed user facility at the "Variable Polarization XUV Beamline" P04 of the synchrotron light source PETRA III operated by DESY in Hamburg, Germany. The careful design of the PIPE ion-optics in combination with the record-high photon flux at P04 has lead to a breakthrough in experimental studies of photon interactions with ionized small quantum systems. This short review provides an overview over the published scientific results from photon-ion merged-beams experiments at PIPE that were obtained since the start of P04 operations in 2013. The topics covered comprise photoionization of ions of astrophysical relevance, quantitative studies of multi-electron processes upon inner-shell photoexcitation and photoionization of negative and positive atomic ions, precision spectroscopy of photoionization resonances, photoionization and photofragmentation of molecular ions and of endohedral fullerene ions., Comment: 10 pages, 9 figures

Synopsis Photoprocesses of the endohedral fullerene ions Sc 3 N @ C 80 + and Sc 3 N @ C 80 − in the gas phase have been experimentally investigated with emphasis on the specific effects of the encapsulated trimetallic nitride cluster Sc3N on the observed reaction yields. Clear evidence of photoexcitation near the Sc L edge is obtained with the dominating contributions visible in the one- and two-electron-removal channels. The experiments are accompanied by model calculations employing density functional theory (DFT).

The aim of this study was to identify skeletal variations in the lumbosacral junction (LSJ) of the German shepherd dog (GSD) compared with other large breeds. The radiographic traits of the LSJ were investigated in a group of 733 GSDs and a control group of 334 dogs of other breeds that were matched in terms of size. Nine morphological and 17 morphometric traits were recorded and analysed. Furthermore, the possibility of a genetic basis for these radiographic features was evaluated by calculation of genetic variance components. Five of the morphological and 14 of the morphometric traits varied significantly between the GSD group and the control group (P

The astrophysical journal 836(2), 166 (2017). doi:10.3847/1538-4357/836/2/166, Single, double, and triple photoionization of Ne$^{+}$ ions by single photons have been investigated at the synchrotron radiation source PETRA III in Hamburg, Germany. Absolute cross-sections were measured by employing the photon–ion merged-beams technique. Photon energies were between about 840 and 930 eV, covering the range from the lowest-energy resonances associated with the excitation of one single K-shell electron up to double excitations involving one K- and one L-shell electron, well beyond the K-shell ionization threshold. Also, photoionization of neutral Ne was investigated just below the K edge. The chosen photon energy bandwidths were between 32 and 500 meV, facilitating the determination of natural line widths. The uncertainty of the energy scale is estimated to be 0.2 eV. For comparison with existing theoretical calculations, astrophysically relevant photoabsorption cross-sections were inferred by summing the measured partial ionization channels. Discussion of the observed resonances in the different final ionization channels reveals the presence of complex Auger-decay mechanisms. The ejection of three electrons from the lowest K-shell-excited Ne$^{+}$$(1s 2s^{2}$ $2p^{6}$ $^{2}$$S_{1/2})$ level, for example, requires cooperative interaction of at least four electrons.

XXX International Conference on Photonic, Electronic, and Atomic Collisions, Cairns, Australia, 25 Jul 2017 - 1 Aug 2017 ; Journal of physics / Conference Series 875, 032034(2017). doi:10.1088/1742-6596/875/4/032034, Cross sections for photoionization and photofragmentation of singly, doubly and triply charged Lu3N@C80 ions have been measured using the photon-ion merged-beams technique at the PETRA III synchrotron light source. The measured spectra exhibit prominent resonance features at energies around the carbon K edge. In contrast to that, no signatures of the nitogen K and lutetium M edges have been found in the experimentally investigated reaction channels., Published by IOP Publ., Bristol

SummaryNeurological cases, especially in foals, are rare in the daily practical work. The most common causes are traumata and infectious diseases of the central nervous system (CNS). This case report provides further insights into the wide spectrum of possible neuropathological lesions by detailing a complex malformation with unilateral neurological signs that occurred later post natum. Thus, clinicians should also be aware of malformations in case of respective neurological patients. A Hanoverian foal was presented with progressive ataxia. General and blood examination revealed no further alterations. By neurologic examination, a unilateral hypermetria was diagnosed and a cysternography of the head was performed. A cerebellar malformation was assumed and the foal was euthanized due to poor prognosis. At necropsy, a unilateral absence of a cerebellar hemisphere and vermis accompanied by contralateral malformation of the mesencephalon was diagnosed. The missing areas of the right cerebellar hemisphere were replaced by a cystic formation. The left part of the mesencephalic lamina quadrigemina was reduced in size and the corpus callosum was hypoplastic. Additional microscopical findings were most obvious near the cyst formation and included angiofibrosis in remaining cerebellar and mesencephalic parenchyma and leptomeninges, heterotopia of cerebellar neurons, sclerosis in cerebellar cortex, focal proliferation of meningeal cells and mild mononuclear perivascular infiltrates. Occassional irregular neuronal arrangement in the mesencephalon was also present. Infectious agents such as Borna disease virus, rabies virus, and equine herpesvirus were not detected. Therefore, the complex malformation in this foal might have been caused by a destructive, possibly ischemic event, or could represent a sequel of a primary retrocerebellar cyst with accompanying compression of adjacent parenchyma.

Aprosencephaly is a rare condition in veterinary and human medicine characterized by the complete absence of telencephalon and diencephalon. Some cases are accompanied by a facial dysmorphism designated as otocephaly. A stillborn lamb had splanchnocranial anomalies that were classified by computed tomography, magnetic resonance imaging, and pathologic examination as aprosencephaly and otocephaly. The brain included parts of the cerebellum and brainstem but no telencephalon, diencephalon, or mesencephalon. The cerebellum had a structurally normal cortex with expression of neuronal nuclear antigen in the inner and doublecortin in the outer granular cell layers, as well as an irregularly situated nucleus dentatus. Aprosencephaly with otocephaly has been described in mice with heterozygous mutations in the Otx2 gene; however, no causative polymorphisms were detected in the Otx2 gene region of this lamb.

Magnetic resonance imaging (MRI) features of brain lesions in 5 dogs and 2 cats characterized by extensive cystic changes of the cerebral hemispheres in terms of a porencephaly are presented. Age at diagnosis ranged from 12 weeks to 7 years. MRI findings were confined to the forebrain. Porencephalic lesions appeared as wedge-shaped parenchymal defects connecting the ventricular system and the subarachnoid space or as large cystic defects in the cerebral hemispheres. Although in two adult dogs the porencephalic lesions were asymptomatic, the other animals showed clinical symptoms depending on the affected cerebral area. Three animals had seizures. Interestingly, four animals showed neurological signs normally not localized to the forebrain (nystagmus, hypermetria, ataxia). Whether these clinical signs are related to impaired function of the cerebral cortex or to not recognizable lesions in the cerebello-vestibular system could not be further clarified. Although the defects develop intrauterine or postnatal, the clinical symptoms can occur later in life. The definition of porencephaly as well as its subclassification is not uniform in veterinary medicine. We suggest the term encephaloclastic porencephaly unregarding the underlying cause of the defect, which cannot be further specified by diagnostic imaging.

Zusammenfassung Gegenstand und Ziel: Computertomographische Untersuchung des Schädels von Katzen mit einem kraniofazialen Trauma. Auswertung der Befunde hinsichtlich des isolierten und gemeinsamen Auftretens von Maxilla-und Orbitafrakturen. Material und Methoden: Prospektive Studie (August 2006 – Juni 2010): Bei Katzen mit kraniofazialem Trauma erfolgte eine computertomographische Untersuchung des Schädels. Ergebnisse: Bei den 38 untersuchten Tieren handelte es sich mit Ausnahme einer Maine-Coonund einer Somali-Katze um Europäische Kurzhaarkatzen. Das Alter der Katzen lag zwischen 11 und 187 Monaten (Durchschnitt 53 Monate). Das Verhältnis männlicher zu weiblicher Tiere betrug 22:16 (1,4). Insgesamt wiesen 27 (71%) Tiere mindestens eine Maxillafraktur auf. Multiple Maxillafrakturen (≥ 2) bestanden bei 16 (42%) Katzen. Die Orbita war bei 28 (74%) Tieren in das Frakturgeschehen involviert. Maxilla-und Orbitafrakturen traten statistisch signifikant (p < 0,001) häufig gemeinsam auf und wurden bei 26 (68%) Katzen diagnostiziert. Die Odds Ratio für das gemeinsame Auftreten dieser Frakturen betrug 87 (p < 0,001). Multiple Frakturen (≥ 2) der knöchernen Augenhöhle kamen bei 16 (57%) der 28 Katzen mit Orbitafrakturen vor. Beidseitige Orbitafrakturen wiesen 25 (67%) Patienten auf (95%-Konfidenzintervall: 48–79%). Am häufigsten (66%) fanden sich Frakturen im Bereich der medialen Orbitawand, gefolgt von Frakturen des Orbitabodens (61%). Schlussfolgerung: Der Einsatz der Computertomographie (CT) zeigte, dass Maxilla-und Orbitafrakturen bei Katzen mit einem kraniofazialen Trauma deutlich häufiger vorkommen als bisher angenommen und bei über der Hälfte der Patienten kombiniert auftreten. Bei Katzen mit Orbitafrakturen ist überwiegend die mediale und ventrale Orbitawand in das Frakturgeschehen involviert. Klinische Relevanz: Maxilla-und Orbitafrakturen kommen bei Katzen mit einem kraniofazialen Trauma häufig vor. Die mittels CT gewonnenen Informationen könnten zukünftig zu einer Optimierung des Behandlungsregimes beitragen.

Although magnetic resonance imaging has been used to examine the brain of domestic ruminants, detailed information relating the precise anatomical features in these species is lacking. In this study the brain structures of calves (Bos taurus domesticus), sheep (Ovis aries), goats (Capra hircus) and a mesaticephalic dog (Canis lupis familiaris) were examined using T2-weighed Turbo Spin Echo sequences; three-dimensional models based on high-resolution gradient echo scans were used to identify brain sulci and gyri in two-dimensional images. The ruminant brains examined were similar in structure and organisation to those of other mammals but particular features included the deep depression of the insula and the pronounced gyri of the cortices, the dominant position of the visual (optic nerve, optic chiasm and rostral colliculus) and olfactory (olfactory bulb, olfactory tracts and piriform lobe) systems, and the relatively large size of the diencephalon.

Der Ultraschall stellt heutzutage das bildgebende Verfahren bei Erkrankungen der Harnblase bei Hund und Katze dar. Im Gegensatz zu anderen Untersuchungsverfahren konnen sonografisch Blasenwand und Inhalt ausgezeichnet beurteilt werden. Da die Harnblase beim Hund in der Regel intraabdominal vor dem Becken und bei der Katze noch weiter kranial liegt, ist sie der Sonografie von transabdominal ideal zuganglich.

Therapie von Pankreastumoren durch partielle Pankreatektomie mittels linearem Stapler bei drei Hunden

Summary Objective: Medial coronoid disease (MCD) is a very common form of elbow joint disease and it’s radiographic diagnosis can be challenging since it is frequently based on the detection of rather subtle primary or secondary changes than on a large primary lesion. We hypothesized that accuracy of radiographic diagnosis of MCD is highly dependent on training and experience level. Methods: Radiographs of 102 canine elbows were evaluated for MCD by four observers with different levels of training and experience. All elbows underwent CT scans and arthroscopy. Sensitivity and specificity of radiographic and CT interpretation was determined using arthroscopy as a gold standard. Interobserver and intraobserver agreement (reliability and repeatability) were assessed by using Cohen’s Kappa (κ) statistic. Results: The sensitivity (92.4–96.7%) of the two experienced observers was almost comparable to that of CT (100%) and significantly higher than that of the two less experienced observers (77.2–80.4%). Reliability of the radiographic diagnosis of MCD was better between observers with higher experience level (κ = 0.74) than between observers of lower or different experience levels (κ =0.07–0.42). Repeatability was better in experienced (κ = 0.73–0.88) than in less experienced observers (κ = 0.31–0.42). Conclusion: Our results confirm that training and experience play important roles in reaching high sensitivity, reliability and repeatability for the radiographic diagnosis of MCD. Clinical relevance: Although radiography is inferior to CT in imaging of the medial coronoid process itself, sensitivity of radiographic diagnosis MCD can be significantly improved with observer experience almost reaching that of CT. Therefore, it is advised that radiographic screening for MCD should be performed by specialists experienced in the radiographic evaluation of elbow joint disease.

Photon-induced fluorescence spectroscopy was applied to measure absolute fluorescence emission cross sections from the main 5s- and first satellite levels of XeII upon photoionization from XeI in a broad exciting-photon energy range (23–28 eV) with 20 meV bandwidth of the exciting radiation and in a narrow energy range (23.25–23.50 eV) with a bandwidth of 1.8 meV. The average fluorescence resolution amounted to 0.07 nm. Fluorescence emission cross sections were computed with taking into account many-electron correlations and doubly excited states. Computed cross sections, especially in integrated form, agree well with the results of experiment. Many features observed in the high resolution experiment are identified to originate from nf-Rydberg series.

Zusammenfassung Gegenstand: Diagnostische Wertigkeit der Computertomographie (CT) und der Magnetresonanztomographie (MRT) im Hinblick auf die Diagnose einer Koronoiderkrankung beim Hund. Material und Methode: Bei klinisch und röntgenologisch für eine Koronoiderkrankung am Ellbogengelenk verdächtigen Hunden wurden eine computertomographische und eine magnetresonanztomographische Untersuchung mit anschließender Arthroskopie des betroffenen Ellbogengelenks durchgeführt. Ergebnisse: Die Untersuchung erfasste 44 Ellbogengelenke von 44 Hunden. Bei den Patienten handelte es sich am häufigsten um Labrador Retriever (38,6%, n = 17), Mischlinge (22,7%, n = 10) und Golden Retriever (11,4%, n = 5). Insgesamt waren 11 Rassen vertreten. Das Alter der 30 Rüden (68%) und 14 Hündinnen (32%) lag zwischen 6 und 117 Monaten (Durchschnitt 2,25 Jahre). Mittels Computertomographie ließen sich folgende Befunde erheben: a) Fissur im Bereich des Koronoids bei 66% (n = 29); b) Fragmente im Bereich des Koronoids bei 55% (n = 24); c) Deformation im Bereich des Koronoids bei allen 44 Gelenken; d) Dichteanstieg im Bereich der Koronoidbasis bei allen 44 Gelenken; e) heterogene Dichtestruktur im Bereich der Spitze des Processus coronoideus medialis ulnae bei 91% (n = 40). Die magnetresonanztomographischen Befunde umfassten: a) Fissur im Bereich des Koronoids bei 59% (n = 26); b) Fragmente im Bereich des Koronoids bei 57% (n = 25); c) Deformation im Bereich des Koronoids bei 86% (n = 38); d) Dichte im Koronoid nicht beurteilbar; e) Dichtestruktur nicht beurteilbar. Schlussfolgerung und klinische Relevanz: Beide Verfahren eignen sich zur Diagnostik einer Koronoiderkrankung beim Hund.

Zusammenfassung Gegenstand: Der Artikel beschreibt klinische Symptomatik, diagnostische Aufarbeitung und chirurgische Therapie eines intrapelvinen Lipoms. Verlauf und Ergebnisse: Die klinische Untersuchung, Röntgenaufnahmen des Abdomens und der zytologische Befund einer mittels Feinnadelaspiration gewonnenen Gewebeprobe ergaben die klinische Verdachtsdiagnose eines intrapelvinen Lipoms. Computertomographisch ließ sich eine klar begrenzte fettdichte Struktur im Beckenkanal ohne Beteiligung der umgebenden Gewebe darstellen, die anhand der Hounsfield-Einheiten als Fettgewebe anzusprechen war. Über einen perinealen Zugang erfolgten eine Teilresektion der Fettgeschwulst und eine Fettabsaugung. Die histopathologische Untersuchung bestätigte den klinischen Verdacht eines einfachen Lipoms. 22 Monate postoperativ ist der Hund symptomfrei. Schlussfolgerung und klinische Relevanz: Einfache Lipome finden sich typischerweise in der Unterhaut und nur in Ausnahmefällen in der Brust-, Bauch- oder Beckenhöhle, wo sie zu einer Funktionseinschränkung anderer Organe oder anatomischer Strukturen führen können. Nach einer exakten Diagnosestellung kann aufgrund des langsamen Wachstums der Lipome eine chirurgische Teilresektion in Verbindung mit einer Liposuktion unter Umständen ausreichen, um dem Patienten über längere Zeit Beschwerdefreiheit zu verschaffen.

The full vibrational progression of the 5p σ 1 Σ u + state of H 2 was identified in a high-resolution absorption measurement. More than 40 new lines have been assigned in the spectrum. The transition probabilities, the widths and the dissociation yields for rovibronic lines with J ″ = 0…3 of the various absorption bands of the fifth (5p σ ) 1 Σ u + state out of the X 1 Σ g + v ″ = 0 ground state were measured over the complete vibrational progression. Predissociation was found to be an efficient de-excitation channel for these levels. The predissociation yields and the dissociation widths were measured for nearly the complete vibrational progression. Resonances of the 5 p σ 1 Σ u + state in the H( n = 3) + H(1s) continuum were observed for the first time. Calculations show that they are located behind a large potential barrier. The comparison between the absolute values of these transition probabilities with the calculated values demonstrates clearly the importance of non-adiabatic couplings ignored in the calculations.

We investigate the photodouble ionization of H2 molecules with 400 eV photons. We find that the emitted electrons do not show any sign of two-center interference fringes in their angular emission distributions if considered separately. In contrast, the quasiparticle consisting of both electrons (i.e., the "dielectron") does. The work highlights the fact that nonlocal effects are embedded everywhere in nature where many-particle processes are involved, This work was funded by the Deutsche Forschungsgemeinschaft (DFG), the BMBF, the European COST Action Grant No. XLIC CM1204, the European Research Council Advanced XCHEM Grant No. 290853, and the MINECO Project Grant No. FIS2013-42002-R. J. L. thanks the DFG for support. We are grateful to the staff of PETRA III for excellent support during the beam time. Raw data are archived at the Goethe-University Frankfurt am Main and are available on request

The position and the intensities of the Q lines of the absorption spectrum of H2 were studied in the 81–72 nm wavelength range, using synchrotron light. The transition probabilities of the transitions with 3 ≤ n ≤ 12 have been measured and compared to calculated values. A good agreement has been found. The main discrepancies observed may well be related to local non-adiabatic couplings not included in the calculations. Vibrational couplings between levels with large Δv values up to Δv = 5 were observed affecting the transition probabilities.

The orientation parameter O10 for the 4p4(1D)5p2P3/2 state of KrII populated in resonant Auger transitions from 3d95p/6p photo-excited states was measured at BESSY II for photon energies between 90.8 eV and 92.9 eV. The (1D)5p2P3/2 satellite was populated in the Raman regime, i.e. with a bandwidth of the exciting photons (10 meV) smaller than the natural width of the 3d95p/6p states. Partial cross sections determined from the measurement of the orientation O10 and alignment A20 are compared with results of calculations where the non-resonant part of the photoionization cross section is computed within the sudden approximation. The electron partial wave analysis as the main intention of this investigation shows that this approach yields partial cross sections for the s1/2 (d5/2) waves that are larger (smaller) than the measured ones.

The absorption spectrum of a double-well state, the state of H2, has been computed and compared with new experimental spectra in the energy range around its dissociation limit. Above the potential barrier, it is shown that the vibronic levels unexpectedly preserve a character linked to a definite well even if this character (the absorption probability) is partly shared by the neighbouring levels. The dissociation cross section presents beat-like oscillations at two frequencies as related to the classical oscillators of the two wells. The agreement with a measured high-resolution spectrum is excellent.

The photoionization cross sections of the 4p shell and the 4s main level and 4p 4(3 P) 5s 4 P 5/2, 3/2 satellite subvalence levels of KrII have been calculated in the 4s-near-threshold range of excitation energies from 28.48 to 28.70 eV. The calculation takes into account the core relaxation by the methods of the theory of non-orthogonal orbitals, the interaction between resonant states through autoionization channels by solving the complex secular equation, and the interaction between the channels of the continuous spectrum in all orders of the perturbation theory by the K-matrix method. Good quantitative agreement between the energy-integrated theoretical and experimental photoionization cross sections for the satellite levels has been obtained for the first time. It is shown that only simultaneous consideration of the above-mentioned effects leads to such agreement. The resonant structure of the photoionization cross sections in this excitation energy range is related to the autoionization decay of the 4p 45s(4 P 1/2)np and 4p 45s(2 P 3/2)np Rydberg series. The specificity of this process is that both series manifest themselves not independently but owing to their strong electrostatic interaction with the prominent 4p 4(1 D)5s 2 D 5/2 6p 3/2 resonance, which lies in this excitation energy range.

Relative cross sections for photoionization of endohedral fullerene ions Lu3N@C80 q+ (q = 1,2,3) have been measured employing the photon-ion merged-beam technique. The investigations include various ionization channels Lu3N@C80 +q→+p (q = 1,2,3 and p = 2,3,4,5,6), in some cases accompanied by fragmentation of the carbon cage. Prominent structures related to the carbon K-shell ionization threshold were observed in the energy range 280–330 eV. These resonance structures have been analyzed in seven product channels and are compared with previously known absorption spectra of several fullerene species. Within the statistical significance of the data, we do not observe any signatures of the N 1s and Lu 3d thresholds in the energy ranges 390–435 eV and 1500–1700 eV, respectively. By comparing the energies for double ionization of Lu3N@C80 + and Lu3N@C80 2+ at the carbon 1s K-shell threshold, we derive a value of 5.0 ± 0.4 °A for the radius of the carbon cage.

The photoabsorption of Ar is studied experimentally and theoretically for energies between 32.5 eV and 33.0 eV. Resonant excitation and autoionization of doubly excited 3p4(3P)4s2P3/2,1/2 np Rydberg states are observed as dominant mechanism to populate doublet and quartet satellites of the 3p44s, 3d configurations. The perturbation of the Rydberg series by promoter states is reproduced by the calculations. Measured and calculated cross sections for the strong decay channels are in good agreement. A mirror behaviour of the 3s vacancy creation and the satellite production and the influence of the radiative decay of high-lying Rydberg states on the shape of a satellite threshold are manifested.

Predissociation of the N+2 C 2Σ+u(v') vibrational levels with v' ≥ 3 was observed via dispersed C 2Σ+u → X 2Σ+g fluorescence in the spectral range of 165–208 nm after resonant 1s−1π*(vr) excitation of N2 and its subsequent autoionization into the N+2 C state. This range is dominated by lines in atomic nitrogen, by overlapped C 2Σ+u(v') → X 2Σ+g(v'') vibrational band sequences with Δv = const and broad unresolved band systems (D, (2))2Πg(v') → A2Πu(v'') in the N+2 molecular ion. With very high fluorescence resolution of about 0.1 nm FWHM individual C 2Σ+u(v') → X 2Σ+g(v'') vibrational bands have been resolved. Calculation of the observed fluorescence spectra by taking into account predissociation and molecular rotation describes well the shape of both individual vibrational bands C 2Σ+u(v') → X 2Σ+g(v'') and the whole band system.

Fluorescence from fragments formed after the de-excitation of the N*2(1s−1π*) resonance has been measured in the spectral range of 135–190 nm. This range is dominated by lines in atomic nitrogen and lines formed by overlapping C2Σ+u(v') → X2Σ+g(v'') bands with Δv = const in the N+2 molecular ion which result from the spectator Auger decays of the N*2(1s−1π*(vr)) resonances. Ab initio calculations of the corresponding potential curves and transition probabilities showed that the observed irregular intensity dependence of the C2Σ+u(v') → X2Σ+g(v'')(Δv = const) fluorescence lines on the vibrational quantum number vr is due to transitions between vibrational levels during the reaction N2(v0 = 0)→ N*2(1s−1π*(vr)) C2Σ+u(v') → X2Σ+g(v'').

The alignment parameter A20 and the orientation parameter O10 for the 4p4(1D)5p2F7/2 and the 4p4(1D)5p2D5/2 states of Kr+ populated in resonant Auger transitions from 3d95p/6p photo-excited states of Kr were measured at BESSY II for photon energies between 91 eV and 92.8 eV. The method of fluorescence polarimetry was applied. A bandwidth of the exciting photons of 10 meV allowed to study A20 and O10 within the natural line width. Interference effects for resonances overlapping due to lifetime broadening were predicted and observed even when separated by 15 times the natural line width. The relative contribution of the three allowed electron partial waves was derived from A20 and O10 as a function of the exciting-photon energy and compared with the calculated contributions. The resulting good overall agreement between experiment and prediction is considered as a noticeable improvement of the understanding of excitation and decay of the prominent Kr 3d95p resonances.

The interaction between resonances through autoionization continua and the interaction between autoionization continua were investigated theoretically and experimentally for the photoionization process of the 4p- and 4s-shells and for the population of 4p4 (3P)5s 4PJ, 4p4 (3P)5s 2PJ and 4p4(3P)4d 4DJ satellites of KrII. Cross sections for the satellite production and the angular distribution parameter of the fluorescence radiation were measured by photon-induced fluorescence spectroscopy after excitationx with linearly polarized monochromatized synchrotron radiation at exciting-photon energies between 28.45 eV and 29.95 eV with an exciting-photon energy resolution of 10 meV (FWHM). Measured cross sections are in good agreement with the computed ones. A refined assignment of resonances in the proximity of the 4s14p65p resonance was performed. It was concluded that there is a strong influence of the core rearrangement, of the interaction between resonances through the autoionization continua and of the interaction between autoionization continua, on the investigated processes on the basis of the observed good overall agreement between the computed and measured quantities.

The decay of doubly excited helium states below the N = 2 threshold, cascading radiatively over three steps, were investigated using the photon-induced fluorescence spectroscopy (PIFS) at BESSY II. Absolute cross sections as the product of the resonance excitation cross section of the doubly excited states and their fluorescence rate to decay into the singly excited 1sms(1S) and 1smd(1D) states were measured. The experiments showed that the (sp,2n+)(1P) states decay predominantly into the 1sns(1S) states, whereas the (pd,2n)(1P) states prefer to decay into the 1snd(1D) states. For the (sp,2n−)(1P) states with n = 4, 5 and 6 we observed a broad and complex decay pattern. In addition the angular distribution of the fluorescence radiation was measured. The results are in good agreement with theoretical predictions. Furthermore, the weakening of the LS coupling scheme and the mixing between singlet and triplet states in helium was confirmed by observation of the 1s6d(3D0,1,2) → 1s2p(3P0,1,2) transition on a doubly excited singlet state.

Photoionization cross-sections for the 4p 4 ( 3 P ) 5s 4 P 5 / 2 , 3 / 2 , 1 / 2 satellites and 4s, 4p main levels of Kr II in the exciting-photon energy range between 28.48 and 28.70 eV with extremely narrow bandwidth (1.7 meV at 28.55 eV) of the monochromatized synchrotron radiation were measured utilizing the photon-induced fluorescence spectroscopy. The observed resonances were assigned to the 4p 4 5s( 4 P 1 / 2 )n p and 4p 4 5s( 2 P 3 / 2 )n p Rydberg series on the basis of calculations performed with taking into account core relaxation and interaction between many resonances and many continua. The calculation shows that the resonance structure in the photoionization channels exists due to 4p 4 ( 1 D ) 5s 2 D 5 / 2 6 p 3 / 2 promoter state which also strongly perturbs the above Rydberg series.

The competition between autoionization and neutral dissociation (ND) of the vibronic Rydberg states 2σ−1u(c4Σ−u)(ns/nd)σg3Σ−u(v = 0, 1) has been investigated using an experiment of photon-induced fluorescence spectroscopy (PIFS) and the simultaneous measurement of the photo ion yield. The experiments were performed with monochromatized synchrotron radiation from BESSY II with a very narrow bandwidth of ΔE = 1.5 meV at 23 eV where it was possible to observe single rotational branches. The experiments are compared to ab initio calculations for the partial autoionization and dissociation widths and to the corresponding simulations of the spectroscopic shape of the rovibronic branches. For more precise calculations of the dissociation widths, diabatic potential curves of the 2σ−1u(c4Σ−u) states of the O+2 are extracted from the adiabatic ones and improved calculations for molecular orbitals of the Rydberg and Auger electrons are used.

Dispersed Kr VUV-fluorescence excitation spectra and photoion yields were recorded in the exciting photon energy range between 28.4 eV and 28.7 eV with extremely narrow bandwidth (1.7 meV at 28.55 eV) of the monochromatized synchrotron radiation used as the exciting photon source. Two series of doubly excited KrI states were observed and identified as the 4s24p4 (3P) 5s 4P1/2 np and the 4s24p4(3P)5s 2P3/2 np series.

The pressure dependence study of the decay of the Lyman-α fluorescence induced by the dissociation of the doubly excited states enables us to determine the 2s-to-2p dissociation channel cross section ratio, and the cross sections of each dissociation channel. Evidence of new dissociations was obtained: the Q11Σ(2) state dissociates into H(2s) + H(1s) and the Q3 states into H(2s) + H(nλ).