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A magnetic bottle time-of-flight spectrometer has been used to perform spectroscopy of Kn+ and Rbn+ states with ionization degrees n of 2, 3 and 4. Energy levels are directly measured by detecting in coincidence the n electrons that are emitted as a result of single photon absorption. Experimental results are compared with the energies from the NIST atomic database and ab initio multiconfiguration Dirac–Fock calculations. Previously unidentified 3p4(3P)3d14D energy levels of K2+ are assigned. [ABSTRACT FROM AUTHOR]

Multielectron coincidence spectroscopy has been used to study the Auger decay following the core (4f)—valence (5d, 6s) double photoionization of atomic mercury. Multiconfiguration Dirac–Fock calculations have been performed to predict the transition energies and populations of the triple ionized Auger final states. A good agreement between the experiment and simulated spectra is found. [ABSTRACT FROM AUTHOR]

Two-electron emission following photoabsorption near the Kr 3d threshold is investigated both experimentally and theoretically. On the experimental side, electron/electron coincidences using a magnetic bottle time-of-flight spectrometer allow us to observe the complete double photo ionization (DPI) continua of selected Kr2+ final states, and to see how these continua are affected by resonant processes in the vicinity of the Kr 3d threshold. The analysis is based on a quantum mechanical approach that takes into account the contribution of three different processes: (A) Auger decay of the inner 3d vacancy with the associated post-collision interaction (PCI) effects, (B) capture of slow photoelectrons into discrete states followed by valence multiplet decay (VMD) of the excited ionic states and (C) valence shell DPI. The dominant process for each Kr2+(4p[?]2) final state is the photoionization of the inner shell followed by Auger decay of the 3d vacancies. Moreover, for the 4p[?]2(3P) and 4p[?]2(1D) final ionic states an important contribution comes from the processes of slow photoelectron capture followed by VMD as well as from double ionization of the outer shell involving also VMD. [ABSTRACT FROM AUTHOR]

Coronavirus disease (COVID-19) is an infectious disease caused by SARS-CoV-2. Elderly people, people with immunodeficiency, autoimmune and malignant diseases, as well as people with chronic diseases have a higher risk of developing more severe forms of the disease. Pregnant women and children can becomesick, although more often they are only the carriers of the virus. Recent studies have indicated that infants can also be infected by SARS-CoV-2 and develop a severe form of the disease with a fatal outcome. Acute Respiratory Distress Syndrome (ARDS) ina pregnant woman can affect the supply of oxygen to the fetus and initiate the mechanism of metabolic disorders of the fetus and newborn caused by asphyxia. The initial metabolic response of the newborn to the lack of oxygen in the tissues is the activation of anaerobic glycolysis in the tissues and an increase in the concentration of lactate and ketones. Lipid peroxidation, especially in nerve cells, is catalyzed by iron released from hemoglobin, transferrin and ferritin, whose release is induced by tissue acidosis and free oxygen radicals. Ferroptosis-inducing factors can directly or indirectly affect glutathione peroxidase through various pathways, resulting in a decrease in the antioxidant capacity and accumulation of lipid reactive oxygen species (ROS) in the cells, ultimately leading to oxidative cell stress, and finally, death. Conclusion: damage to the mitochondria as a result of lipid peroxidation caused by the COVID-19 disease can cause the death of a newborn and pregnant women as well as short time and long-time sequelae.

Single-photon multiple photoionization results from electron correlations that make this process possible beyond the independent electron approximation. To study this phenomenon experimentally, the detection in coincidence of all emitted electrons is the most direct approach. It provides the relative contribution of all possible multiple ionization processes, the energy distribution between electrons that can reveal simultaneous or sequential mechanisms, and, if possible, the angular correlations between electrons. In the present work, we present a new magnet design of our magnetic bottle electron spectrometer that allows the detection of multiply charged Xe n + ions in coincidence with n electrons. This new coincidence detection allows more efficient extraction of minor channels that are otherwise masked by random coincidences. The proof of principle is provided for xenon triple ionization.

Single-site Double-Core Hole (ss-DCH or K -2 ) and two-site Double-Core Hole (ts-DCH or K -1 K -1 ) photoelectron spectra including satellite lines were experimentally recorded for the aromatic C 6 H 6 molecule using the synchrotron radiation and multielectron coincidence technique. Density functional theory and post-Hartree-Fock simulations providing binding energies and relative intensities allow us to clearly assign the main K -2 line and its satellites. K -1 K -1 states' positions and assignments are further identified using a core-equivalent model. We predict that, contrary to what has been observed in the C 2 H 2n series of molecules, the K -1 K -1 energy-level ordering in C 6 H 6 does not reflect the core-hole distances between the two holes.

This paper examines the possibility of using basalt-based glass ceramics for construction of structural parts of equipment in metallurgy and mining. An ultrasonic vibration method with a stationary sample pursuant to the ASTM G32 standard was used to evaluate the possibility of the glass ceramic samples application in such operating conditions. As the starting material for synthesis of samples, olivine-pyroxene basalt from the locality Vrelo-Kopaonik Mountain (Serbia) was used. In order to obtain pre-determined structure and properties of basalt-based glass ceramics, raw material preparation methods through the sample crushing, grinding, and mechanical activation processes have been examined together with sample synthesis by means of melting, casting, and thermal treatment applied for the samples concerned. The mass loss of samples in function of the cavitation time was monitored. Sample surface degradation level was quantified using the image analysis. During the test, changes in sample morphology were monitored by means of the scanning electronic microscopy method. The results showed that basalt-based glass ceramics are highly resistant to cavitation wear and can be used in similar exploitation conditions as a substitute for other metal materials.

The literature was reviewed with respect to deinking flotation methods with toner samples, specifically emphasizing the speciation of copy machine and laser printing, which produce an increasing quantity of paper that is difficult to recycle. Speciation here refers to the physical-chemical characteristics of the toner, which change because of the polymerization (fusion) and oxidation process, due to exposure to heat, light and oxygen (air) during the printing process. To simulate the deinking flotation, after the ideal disintegration process, samples of toner were prepared in order to provide free toner particles. Synthetic toner has iron content and the same physical-chemical features as free disintegrated printed toner particles.We report the toner (I) and fibre (Y) recovery and the brightness (B) of laboratory filter pads formed of deinked product as deinking efficiencies. The application of oleic acid as the collector in the flotation stage gives a better flotation recovery in alkaline than in acidic conditions. The highest brightness (BF = 93.66%) and flotation recoveries (I = 90, Y = 92.82%) were achieved during testing at an oleic acid concentration of 3.38·10(-6) mol l(-1), which is the lowest dose used. This makes the use of oleic acid economical and environmentally friendly., (© The Author(s) 2016.)

We have studied, for the first time by electron spectroscopy, the Auger decay of the 4d→nf (n=4,5) resonances in Xe^{5+} ion. By detecting in coincidence the Auger electrons with the resulting Xe^{6+} ions, we unravel the contribution of the different final ionic states to the total cross section measured by ion spectroscopy. A strong intensity of 5s5p satellite lines has been observed, up to 4 times stronger than the 5s^{2} main lines. This unexpected behavior is confirmed by multiconfiguration Dirac-Fock calculations. This technique provides the most stringent test for theoretical models and allows us to disentangle the contribution of ions in the ground and metastable states in the target beam.

We present in detail a theoretical model that provides absolute cross sections for simultaneous core-ionization core-excitation (K(-2)V) and compare its predictions with experimental results obtained on the water molecule after photoionization by synchrotron radiation. Two resonances of different symmetries are assigned in the main K(-2)V peak and comparable contributions from monopolar (direct shake-up) and dipolar (conjugate shake-up) core-valence excitations are identified. The main peak is observed with a much greater width than the total experimental resolution. This broadening is the signature of nuclear dynamics.

The formalism developed in the companion Paper I is used here for the interpretation of spectra obtained recently on the nitrogen molecule. Double core-hole ionization K(-2) and core ionization-core excitation K(-2)V processes have been observed by coincidence electron spectroscopy after ionization by synchrotron radiation at different photon energies. Theoretical and experimental cross sections reported on an absolute scale are in satisfactory agreement. The evolution with photon energy of the relative contribution of shake-up and conjugate shake-up processes is discussed. The first main resonance in the K(-2)V spectrum is assigned to a K(-2)π(∗) state mainly populated by the 1s→ lowest unoccupied molecular orbital dipolar excitation, as it is in the K(-1)V NEXAFS (Near-Edge X-ray Absorption Fine Structure) signals. Closer to the K(-2) threshold Rydberg resonances have been also identified, and among them a K(-2)σ(∗) resonance characterized by a large amount of 2s/2p hybridization, and double K(-2)(2σ(∗)/1π/3σ)(-1)1π(∗2) shake-up states. These resonances correspond in NEXAFS spectra to, respectively, the well-known σ(∗) shape resonance and double excitation K(-1)(2σ(∗)/1π/3σ)(-1)1π(∗2) resonances, all being positioned above the threshold.

We provide a final state selective experimental study on the direct double photoionization of the valence states of benzene and pyrrole. The experiment is carried out using a magnetic-bottle electron time-of-flight coincidence setup at the incident photon energy region of 25-120 eV. We discuss on the recently discovered phenomenon of so-called Cooper pair formation [R. Wehlitz et al., Phys. Rev. Lett. 109, 193001 (2012)] and show that our experiment provides contradicting evidence on its existence in the proposed form. We confirm the finding of a new two-electron continuum resonance structure observed at about 30–70 eV above the double ionization threshold in benzene, provide further information from it, and suggest an alternative explanation.

We have observed single photon double K-shell photoionization in the C(2)H(2n) (n=1-3) hydrocarbon sequence and in N(2) and CO, using synchrotron radiation and electron coincidence spectroscopy. Our previous observations of the K(-2) process in these molecules are extended by the observations of a single photon double photoionization with one core hole created at each of the two neighboring atoms in the molecule (K(-1)K(-1) process). In the C(2)H(2n) sequence, the spectroscopy of K(-1)K(-1) states is much more sensitive to the bond length than conventional electron spectroscopy for chemical analysis spectroscopy based on single K-shell ionization. The cross section variation for single photon K(-1)K(-1) double core ionization in the C(2)H(2n) sequence and in the isoelectronic C(2)H(2n), N(2) and CO molecules validates a knock-out mechanism in which a primary ionized 1s photoelectron ejects another 1s electron of the neighbor atom. The specific Auger decay from such states is clearly observed in the CO case.

Direct measurements of the photoelectrons or Auger electrons associated with inner shell ionization of positively charged ions are extremely difficult and rarely realized. We propose an alternative method to simulate such measurements, based on core valence double photoionization of the neutral species. As an example, we obtain the spectroscopy, lifetimes, and Auger decays of the states arising from 2p inner shell ionisation of an Ar(+) ion. Observations compare well with theoretical predictions obtained within multiconfigurational Dirac-Fock formalism.

We have investigated a local chemical environment effect on Auger spectra of ethyl trifluoroacetate (C(4)H(5)F(3)O(2)), using multi-electron coincidence spectroscopy and high-resolution electron spectroscopy. Site-specific KVV Auger spectra for each carbon atom, and for the fluorine and oxygen atoms are presented. The extent of hole localization in the final dicationic states was investigated with the help of theoretical calculations based on a two-hole population analysis. The Auger spectra have been simulated using a statistical approach. It is found that all Auger decays populate mainly localized dicationic states, with the two holes located either on the same fluorine atom or on adjacent fluorine atoms. While the decay of the F 1s hole populates exclusively the former states, the latter class of states is also populated by the decay of the C and O 1s holes.

Auger decay of the C(2)H(2) double core-hole (DCH) states, including the single-site DCH (C1s(-2)), two-site DCH (C1s(-1)C1s(-1)), and satellite (C1s(-2)π(-1)π∗(+1)) states, has been investigated experimentally using synchrotron radiation combined with multi-electron coincidence method, and theoretically with the assumption of the two-step sequential model for Auger decay of the DCH states. The theoretical calculations can reproduce the experimental two-dimensional Auger spectra of the C(2)H(2) single-site DCH and satellite decays, and allow to assign the peaks appearing in the spectra in terms of sequential two-electron vacancy creations in the occupied valence orbitals. In case of the one-dimensional Auger spectrum of the C(2)H(2) two-site DCH decay, the experimental and calculated results agree well, but assignment of peaks is difficult because the first and second Auger components overlap each other. The theoretical calculations on the Auger decay of the N(2) single-site DCH state, approximately considering the effect of nuclear motion, suggest that the nuclear motion, together with the highly repulsive potential energy curves of the final states, makes an important effect on the energy distribution of the Auger electrons emitted in the second Auger decay.

Auger decay of an inner shell hole is an efficient way to create multiply charged ions in the gas phase. We illustrate this with the example of the argon 2s decay, and show that multi-electron coincidence spectroscopy between the 2s photoelectron and all released Auger electrons leads to a complete reconstruction of the Ar 2s decay cascade. Spectra of the intermediate and final Ar(n+) states are obtained and are compared with a theoretical model., (This journal is © the Owner Societies 2011)

We observe the formation in a single-photon transition of two core holes, each at a different carbon atom of the C2H2 molecule. At a photon energy of 770.5 eV, the probability of this 2-site core double ionization amounts to 1.6 ± 0.4% of the 1-site core double ionization. A simple theoretical model based on the knockout mechanism gives reasonable agreement with experiment. Spectroscopy and Auger decays of the associated double core hole states are also investigated.

Spectra of triply ionized CO(2) have been obtained from photoionization of the molecule using soft x-ray synchrotron light and an efficient multi-electron coincidence technique. Although all states of the CO(2) (+++) trication are unstable, the ionization energy for formation of molecular ions at a geometry similar to that of the neutral molecule is determined as 74 ± 0.5 eV., (© 2011 American Institute of Physics)

The direct observation of triple photoionization involving one inner shell and two valence electrons is reported. The energy distribution of the three photoelectrons emitted from Ne is obtained using a very efficient multielectron coincidence method using the magnetic bottle electron spectroscopic technique. A predominance of the direct path to triple photoionization for the formation of Ne3+ in the 1s 2s2 2p4 configuration is observed. It is demonstrated that the energy distribution evolves with photon energy and indicates a significant difference with triple photoionization involving only valence electrons.

We present an experimental and theoretical study of triply charged hydrogen bromide ions formed by photoionization of the inner 3d shell of Br. The experimental results, obtained by detecting the 3d photoelectron in coincidence with the two subsequent Auger electrons, are analyzed using calculated potential energy curves of HBr3+. The competition between the short-range chemical binding potential and the Coulomb repulsion in the dissociative process is shown. Two different mechanisms are observed for double Auger decay: one, a direct process with simultaneous ejection of two Auger electrons to final HBr3+ ionic states and the other, a cascade process involving double Auger decay characterized by the autoionization of Br*+ ion subsequent to the HBr2+ fragmentation.

The formation of hollow molecules (with a completely empty K shell in one constituent atom) through single-photon core double ionization has been demonstrated using a sensitive magnetic bottle experimental technique combined with synchrotron radiation. Detailed properties are presented such as the spectroscopy, formation, and decay dynamics of the N(2)(2+) K(-2) main and satellite states and the strong chemical shifts of double K holes on an oxygen atom in CO, CO2, and O2 molecules.

Spectra of triply charged carbon disulphide have been obtained by measuring, in coincidence, all three electrons ejected in its formation by photoionization. Measurements of the CS(2)(3+) ion in coincidence with the three electrons identify the energy range where stable trications are formed. A sharp peak in this energy range is identified as the (2)Pi ground state at 53.1+/-0.1 eV, which is the lowest electronic state according to ab initio molecular orbital calculations. Triple ionization by the double Auger effect is provisionally divided, on the basis of the pattern of energy sharing between the two Auger electrons into contributions from direct and cascade Auger processes. The spectra from the direct double Auger effect via S 2p, S 2s, and C 1s hole states contain several resolved features and show selectivity based on the initial charge localization and on the identity of the initial state. Triple ionization spectra from single Auger decay of S 2p-based core-valence states CS(2)(2+) show retention of the valence holes in this Auger process. Related ion-electron coincidence measurements give the triple ionization yields and the breakdown patterns in triple photoionization at selected photon energies from 90 eV to above the inner shell edges.

We demonstrate that the observation of slow electrons emitted in the decay of molecular core-excited states can be a sensitive probe of the double Auger processes, and that in combination with electron-electron coincidence spectroscopy, it can provide clear insight into the mechanisms involved. The present study identifies all cascade Auger paths from the C1s-to-Rydberg states in CO to final states of CO2+. One pathway includes the first directly identified case of molecular level-to-level autoionization of a cation and shows remarkable selectivity for a specific final state.

We investigate the use of complex absorbing potentials for the calculation of partial cross sections in multichannel photofragmentation processes. An exactly solvable, coupled-two-channel problem involving square-well potentials is used to compare the performance of various types of absorbing potentials. Special emphasis is given to the near-threshold regions and the conditions under which the numerical results are able to reproduce the Wigner threshold laws. It was found that singular, transmission-free absorbing potentials perform better than those of power or polynomial form.

A magnetic bottle spectrometer of the type recently developed by Eland et al. [Phys. Rev. Lett. 90, 053003 (2003).] has been implemented for use with synchrotron radiation, allowing multidimensional electron spectroscopy. Its application to the Xe 4d double Auger decay reveals all the energy pathways involved. The dominant path is a cascade process with a rapid (6 fs) ejection of a first Auger electron followed by the slower (>23 fs) emission of a second Auger electron. Weaker processes implying 3 electron processes are also revealed, namely, direct double Auger and associated Rydberg series.

We combine the Lanczos algorithm with the absorbing-potential method, implemented in a discrete variable representation to calculate the near-threshold photodissociation cross sections of CH+. The method is iterative, based on a continued fraction representation of the Green function and avoids any explicit matrix diagonalization. A very good agreement is found with experiment and close-coupling calculations., ((c) 2005 American Institute of Physics.)