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The generally accepted pathway to Local Thermodynamic Equilibrium (LTE) in atomic physics, where collision rates need to be much larger than radiative decay rates, is extended to complex autoionizing states. It is demonstrated that the inclusion of the non-radiative decay (autoionization rate) on the same footing, like radiative decay, i.e., the LTE criterion n e , c r i t × C ≫ A + Γ ( n e , c r i t is the critical electron density above which LTE holds, C is the collisional rate coefficient, and A is the radiative decay rate) is inappropriate for estimating the related critical density. An analysis invoking simultaneously different atomic ionization stages identifies the LTE criteria as a theoretical limiting case, which provides orders of magnitude too high critical densities for almost all practical applications. We introduced a new criterion, where the critical densities are estimated from the non-autoionizing capture states rather than from the autoionizing states. The new criterion is more appropriate for complex autoionizing manifolds and provides order of magnitude reduced critical densities. Detailed numerical calculations are carried out for Na-like states of aluminum, where autoionization to the Ne-like ground and excited state occurrences are in excellent agreement with the new criterion. In addition, a complex multi-electron atomic-level structure and electron–electron correlation are identified as simplifying features rather than aggravating ones for the concept of thermalization. [ABSTRACT FROM AUTHOR]

This study reports on the absolute photoionization cross sections for the magnesium-like Cl5+ ion over the 190–370 eV photon energy range, corresponding to the L-shell (2s and 2p subshells) excitation regime. The experiments were performed using the Multi-Analysis Ion Apparatus (MAIA) on the PLéIADES beamline at the SOLEIL synchrotron radiation storage ring facility. Single and double ionization ion yields, produced by photoionization of the 2p subshell of the Cl5+ ion from the 2p63s2 1S0 ground state and the 2p63s3p 3P0,1,2 metastable levels, were observed, as well as 2s excitations. Theoretical calculations of the photoionization cross sections using the Multi-Configuration Dirac-Fock and R-matrix approaches were carried out, and the results were compared with the experimental data. The Cl5+ results were examined within the overall evolution of L-shell excitation for the early members of the Mg-like isoelectronic sequence (Mg, Al+, Si2+, S4+, Cl5+). Characteristic photon energies for P3+ were estimated by interpolation. [ABSTRACT FROM AUTHOR]

The generally accepted pathway to Local Thermodynamic Equilibrium (LTE) in atomic physics, where collision rates need to be much larger than radiative decay rates, is extended to complex autoionizing states. It is demonstrated that the inclusion of the non-radiative decay (autoionization rate) on the same footing, like radiative decay, i.e., the LTE criterion ne,crit×C≫A+Γ (ne,crit is the critical electron density above which LTE holds, C is the collisional rate coefficient, and A is the radiative decay rate) is inappropriate for estimating the related critical density. An analysis invoking simultaneously different atomic ionization stages identifies the LTE criteria as a theoretical limiting case, which provides orders of magnitude too high critical densities for almost all practical applications. We introduced a new criterion, where the critical densities are estimated from the non-autoionizing capture states rather than from the autoionizing states. The new criterion is more appropriate for complex autoionizing manifolds and provides order of magnitude reduced critical densities. Detailed numerical calculations are carried out for Na-like states of aluminum, where autoionization to the Ne-like ground and excited state occurrences are in excellent agreement with the new criterion. In addition, a complex multi-electron atomic-level structure and electron–electron correlation are identified as simplifying features rather than aggravating ones for the concept of thermalization.

We use ab initio molecular dynamics (AIMD) calculations and quasi-chemical theory (QCT) to study the inner-shell structure of F-(aq) and to evaluate that single-ion free energy under standard conditions. Following the "no split occupancies" rule, QCT calculations yield a free energy value of -101 kcal/mol under these conditions, in encouraging agreement with tabulated values (-111 kcal/mol). The AIMD calculations served only to guide the definition of an effective innershell constraint. QCT naturally includes quantum mechanical effects that can be concerning in more primitive calculations, including electronic polarizability and induction, electron density transfer, electron correlation, molecular/atomic cooperative interactions generally, molecular flexibility, and zero-point motion. No direct assessment of the contribution of dispersion contributions to the internal energies has been attempted here, however. We anticipate that other aqueous halide ions might be treated successfully with QCT, provided that the structure of the underlying statistical mechanical theory is absorbed, i.e., that the "no split occupancies" rule is recognized. [ABSTRACT FROM AUTHOR]

This study reports on the absolute photoionization cross sections for the magnesium-like Cl5+ ion over the 190–370 eV photon energy range, corresponding to the L-shell (2s and 2p subshells) excitation regime. The experiments were performed using the Multi-Analysis Ion Apparatus (MAIA) on the PLéIADES beamline at the SOLEIL synchrotron radiation storage ring facility. Single and double ionization ion yields, produced by photoionization of the 2p subshell of the Cl5+ ion from the 2p63s2 1S0 ground state and the 2p63s3p 3P0,1,2 metastable levels, were observed, as well as 2s excitations. Theoretical calculations of the photoionization cross sections using the Multi-Configuration Dirac-Fock and R-matrix approaches were carried out, and the results were compared with the experimental data. The Cl5+ results were examined within the overall evolution of L-shell excitation for the early members of the Mg-like isoelectronic sequence (Mg, Al+, Si2+, S4+, Cl5+). Characteristic photon energies for P3+ were estimated by interpolation.

We have studied the production of neutral high-Rydberg (HR) fragments from the CH4 molecule at the C 1s → 3p excitation and at the C 1s ionization threshold. Neutral fragments in HR states were ionized using a pulsed electric field and the resulting ions were mass-analyzed using an ion time-of-flight spectrometer. The atomic fragments C(HR) and H(HR) dominated the spectra, but molecular fragments CHx(HR), x = 1-3, and H2(HR) were also observed. The production of HR fragments is attributed to dissociation of CH4+ and CH42+ ions in HR states. Just above the C 1s ionization threshold, such molecular ionic states are created when the C 1s photoelectron is recaptured after single or double Auger decay. Similar HR states may be reached directly following resonant Auger decay at the C 1s → 3p resonance. The energies and geometries of the parent and fragment ions have been calculated in order to gain insight into relevant dissociation pathways. [ABSTRACT FROM AUTHOR]

The emission of low-energy electrons from H2O has been investigated at photon excitation energies in the vicinity of the O 1s ionization threshold. Neutral oxygen Rydberg atoms (O*) were found to form, and the correlation between the initial inner-shell excited state of H2O and the Rydberg state of O* was determined. The initially excited electron in a Rydberg orbital is shown to remain associated with O* even after the cleavage of two O-H bonds.We also show that the energy discrepancy between two Rydberg states of H2O and O* can be explained by the influence of the post-collision interaction, which becomes stronger as the excitation energy approaches the 1s ionization threshold. [ABSTRACT FROM AUTHOR]

Multi-coincidence experiments with detection of both electrons and ions from decay of core-excited and core-ionized states of CO2 confirm that O2+ is formed specifically in Auger decay from the C1s-π* and O1s-π* resonances. Molecular rearrangement occurs by bending in the resonant states, and O2+ is produced by both single and double Auger decay. It is suggested that electron capture by C+ after partial dissociation in the doubly ionized core of excited CO2+, formed by shake-up in spectator resonant Auger decay, accounts for high kinetic energy and high internal energy in some C + O2+ fragments. [ABSTRACT FROM AUTHOR]

The dispute about whether the 1 s core-hole is localized on one atom or delocalized over both in a homonuclear diatomic molecule has continued for decades, which has been extensively studied by the photoelectron and electron–ion coincidence spectroscopies. For N _2 , if the 1 s core-hole is delocalized, the K-shell excitation into the 1 π _g orbital should split into two components, i.e., the dipole-allowed transition from the ungerade 1 σ _u state and the dipole-forbidden transition from the gerade 1 σ _g state. However, only the dipole-allowed transition has been observed up to now. Here, we report the inner-shell electron energy loss spectra of N _2 at different scattering angles with an incident electron energy of 1500 eV and an energy resolution of 65 meV. The vibrational structures of both the dipole-allowed ${(1s{\sigma }_{u})}^{-1}{(1{\pi }_{g})}^{1}$ and dipole-forbidden ${(1s{\sigma }_{g})}^{-1}{(1{\pi }_{g})}^{1}$ states of N _2 have been identified at different momentum transfers. The splitting between the ${(1{\sigma }_{g})}^{-1}{(1{\pi }_{g})}^{1}$ and ${(1{\sigma }_{u})}^{-1}{(1{\pi }_{g})}^{1}$ states with the reverse symmetry is determined to be 67 ± 7 meV. Moreover, the momentum transfer dependence behavior of the transition intensity ratio agrees with the theoretical predictions, as increasing to a maximum and then decreasing. The experimental observations clearly show that the inner most electrons can be described by 1 σ _g and 1 σ _u , which indicates that the inner-shell 1 s core-hole of N _2 is delocalized over two N atoms based on the excitation process.

Statistical models combined with the local plasma frequency approach applied to the atomic electron density are employed to study the photoionization cross-section for complex atoms. It is demonstrated that the Thomas–Fermi atom provides surprisingly good overall agreement even for complex outer-shell configurations, where quantum mechanical approaches that include electron correlations are exceedingly difficult. Quantum mechanical photoionization calculations are studied with respect to energy and nl quantum number for hydrogen-like and non-hydrogen-like atoms and ions. A generalized scaled photoionization model (GSPM) based on the simultaneous introduction of effective charges for non-H-like energies and scaling charges for the reduced energy scale allows the development of analytical formulas for all states nl. Explicit expressions for nl = 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, and 5s are obtained. Application to H-like and non-H-like atoms and ions and to neutral atoms demonstrates the universality of the scaled analytical approach including inner-shell photoionization. Likewise, GSPM describes the near-threshold behavior and high-energy asymptotes well. Finally, we discuss the various models and the correspondence principle along with experimental data and with respect to a good compromise between generality and precision. The results are also relevant to large-scale integrated light–matter interaction simulations, e.g., X-ray free-electron laser interactions with matter or photoionization driven by a broadband radiation field such as Planckian radiation. [ABSTRACT FROM AUTHOR]

The volumetric K α emission rate of argon emitted from the electron cyclotron resonance (ECR) heated plasmas of the JYFL (University of Jyväskylä, Department of Physics) 14 GHz ECR ion source (ECRIS) and the 14.5 GHz Grenoble Test Source (GTS) at iThemba Laboratory for Accelerator Based Sciences have been measured to gain an understanding of the influence of the ion source tune parameters on the absolute inner shell ionization rate. It was observed that the behaviour of the ionization rate and the extracted ion beam currents react differently, depending the parametric sweep performed. The neutral gas pressure and incident microwave power was found to have the strongest influence on the ionization rate. At high neutral gas pressure, the absolute inner shell ionization rate was found to saturate. This observation is as a result of the plasma energy content becoming insufficient to sustain the growth in ionization rate. It was also observed that the incident microwave power should be increased much more to counter the decrease in high charge state production as a result of the gas increase and subsequent increase in charge exchange. At low incident microwave, the ionization rate per unit absorbed microwave power was found to be high, which suggests that the inner shell ionization process is driven by the ion dynamics as opposed to the electron dynamics. The influence of the biased disc voltage and magnetic field configuration on the ionization rate was found to be minimal. This led to the suggestion that these two tune parameters does not directly impact the warm electron population of the ECRIS plasma during the parametric sweeps. The K α emission rate can be used as an additional tool for benchmarking the results of numerical simulation codes on ECRIS plasmas. [ABSTRACT FROM AUTHOR]

Inner shell excitation spectroscopy is a local probe of the unoccupied electronic structure in the immediate vicinity of the core excited atom. As such, one might expect the inner shell spectrum of a given unit (a molecular fragment or a repeat unit of a solid) to be largely independent of where that unit is located. This is often an implicit assumption in spectral analysis and analytical applications. However, there are situations where inner shell excitation spectra exhibit significant sensitivity to their local environment. Here I categorize the ways in which inner shell spectra are affected by their local environment, and give examples from a career dedicated to developing a better understanding of inner shell excitation spectroscopy, its experimental techniques, and applications. [ABSTRACT FROM AUTHOR]

The interaction of CHI molecules with 100 fs 800 nm linearly polarized laser fields has been investigated at the intensity region from 2.6 × 10 to 5.8 × 10 W/cm by means of a velocity map imaging method. The kinetic energy distribution of the various atomic fragment ions I ( q = 1-3) has been measured and reproduced by a fit of multiple Gaussian functions. Several dissociative ionization and Coulomb explosion channels were identified for I ( q = 1-3). As expected for a geometric alignment dominated interaction process the anisotropic angular recoil distributions of the atomic ion fragments are peaked in the laser polarization direction. The kinetic energy release (KER) of I ( q = 1-3) depending upon the laser intensity has been investigated. The relative weight of the various contributions from the identified dissociative ionization (DI) and Coulomb explosion (CE) channels is found to depend strongly on the laser intensity. Graphical abstract: [ABSTRACT FROM AUTHOR]

Density matrix equations for ultrafast electron-hole dynamics in solid target under intense x-rays are presented. The theory is an extension of the usual optical Bloch equations to the case of intense x-ray free-electron lasers, where the creation of multiple core holes and the associated orbital relaxation dynamics are additionally incorporated through the cluster model combined with the time-dependent unrestricted Hartree–Fock approximation. Numerical examples are demonstrated for K -edge excitation of sodium by a femtosecond x-ray pulse; nonlinear dynamics of absorption, orbital energy shifts and induced electric polarization are discussed. [ABSTRACT FROM AUTHOR]

The energies, fine structure splittings, transition rates, and lifetimes of inner-shell excited sextet states 1s2s2p2 nl, ( n = 2-7; l = s, p, d) and 1s2p33p of the boron isoelectronic sequence ( Z = 8-13) are investigated using the multi-configuration Rayleigh-Ritz variation method. The mass polarization effect and relativistic corrections are included by first-order perturbation theory. Configuration structures of the high- n inner-shell excited sextet series 6Se,o( m) and 6Pe,o( m) ( m = 1-5) of boron-like Na6+ ion are assigned. The wavelengths and transition rates of electric-dipole transitions between 6Pe( m) and 6Po( m) ( m = 1-5) states are calculated. The quantum electrodynamics (QED) effects and higher order relativistic corrections are also considered to obtain more accurate transition wavelengths. The predicted transition wavelengths agree well with the available theoretical and experimental data. The lifetimes for the inner-shell excited sextet states 6Pe( m) ( m = 1-5) are also reported and discussed with the increase of nuclear charge number, Z. These theoretical data are useful for the identification of spectral lines in experiments and the design of XUV and soft X-ray lasers. [ABSTRACT FROM AUTHOR]

O 1s inner-shell excitation spectra of a number of vapor phase molecules containing peroxide bonds – hydrogen peroxide (H 2 O 2 ), di-t-butylperoxide ( t BuO t Bu), benzoyl peroxide, ((C 6 H 5 (CO)O) 2 ), luperox-F [1,3(4)-bis(tertbutylperoxyisopropyl) benzene], and analogous, non-peroxide compounds – water, t-butanol and benzoic acid have been measured. C 1s spectra are also reported. O 1s spectra of solid benzoic acid, di-t-butylperoxide and luperox-F recorded using a scanning transmission X-ray microscope, are also reported, and compared to the corresponding gaseous spectra. Spectral interpretation was aided by comparing the spectra of the peroxide and non-peroxide counterparts and with ab initio calculations. A characteristic O 1s → σ ∗ O–O transition at 533.0(3) eV is identified in each peroxide species, which is absent in the corresponding non-peroxide counterpart species. The energy and intensity of the 533 eV peroxide feature is stable and thus useful for analysis of peroxides in mixtures, such as tracking residual peroxide initiators, or peroxides produced in fuel cells. [ABSTRACT FROM AUTHOR]

Phenolic compounds were extracted from chestnut inner shell using aqueous alcohols and alkaline solutions (50% ethanol, 50% methanol, 1% NaOH, and 2% NaOH) at different temperatures (25–90 °C). The phenolic composition, antioxidant activity, and deodorizing activity of the extracts were evaluated for comparison. Total phenolic content and antioxidant activity were increased as the extraction temperature increased. However, the phenolic composition and antioxidant activity were significantly different among the extracts prepared under different conditions. Aqueous ethanol (50%, v/w) was most effective in extracting the total phenolics, resulting in the highest DPPH radical scavenging activity. The alkaline solutions appeared more effective in extracting specific phenolics, such as tannins and flavonoids, than aqueous alcohols. Moreover, the alkaline extracts exhibited the higher activities in deodorizing trans -2-nonenal and methyl mercaptan than the alcoholic extracts. The deodorizing activity of chestnut inner shell extracts (CISE) were positively correlated to the residual contents of tannins and flavonoids ( R 2 = 0.85–0.94, and 0.81–0.93, respectively). [ABSTRACT FROM AUTHOR]

The electron shakeup-plus-shakeoff probabilities accompanying M-shell vacancy creation have been calculated for elements between Z = 72 and 92. The calculations were performed relativistically in the sudden approximation by the use of the Dirac-Fock-Slater wave functions. The relativistic effects are demonstrated in comparison with the nonrelativistic calculations, and the validity of the approximation method based on the difference in the effective nuclear charge is discussed. The dependence of different initial M-subshell vacancies on the shake probability is studied. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

It has been experimentally achieved atomic resolution imaging by using secondary electron (SE) signals in a scanning transmission electron microscope with aberration correction. The underlying physical mechanism needs to be understood and has attracted considerable theoretical interest. Several recent calculations taking account of the inner-shell ionization for high-energy SE production have not included the cascade production of low-energy SE signals which was believed to destroy the local information in SE imaging. In this work, we have developed a new theoretical method, a quantum Monte Carlo simulation, to calculate atomic resolution SE image by including every physical factor in SE generation, transportation and emission for a crystalline solid. This quantum Monte Carlo simulation method combines the Bohmian quantum trajectory method for treating electron elastic scattering and diffraction in a crystal with a conventional Monte Carlo sampling of inelastic scattering events along quantum trajectory paths. Simulation of atomic resolution SE image for atom columns in a copper crystal is performed. The contribution of the inner-shell excitation to atomic resolution SE imaging is studied. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Using the adaptive optics system of the Large Binocular Telescope, we have obtained near-infrared camera PISCES images of the inner shell of the nebula around the luminous blue variable star P Cygni in the [Fe ii] emission line at 1.6435 μm. We have combined the images in order to cover a field of view of about 20 arcsec around P Cygni, thus providing the high-resolution (0.08 arcsec) two-dimensional spatial distribution of the inner shell of the P Cygni nebula in [Fe ii]. We have identified several nebular emission regions that are characterized by a signal-to-noise ratio > 3. A comparison of our results with those available in the literature shows full consistency with the findings of Smith & Hartigan, which are based on radial velocity measurements, and relatively good agreement with the extension of emission nebula in [N ii] λ6584 found by Barlow et al. We have clearly also detected extended emission inside the radial distance R = 7.8 arcsec and outside R = 9.7 arcsec, which are the nebular boundaries proposed by Smith & Hartigan. New complementary spectroscopic observations are planned in order to measure radial velocities and to derive the three-dimensional distribution of the P Cygni nebula. [ABSTRACT FROM PUBLISHER]

The recent development of high brightness 3 rd generation soft X-ray sources and high energy resolution electron spectrometers made it possible to accurately trace quantum phenomena associated to the vibrational dynamics in core-excited molecules. The present paper reviews the recent results on mapping of vibrational wave functions and molecular potentials based on electron spectroscopy. We discuss and compare the mapping phenomena in various systems, stressing the advantages of the resonant X-ray scattering for studying of the nuclear dynamics and spectroscopic constants of small molecules. The experimental results discussed in the paper are most often accompanied by state-of-the-art ab initio calculations allowing for a deeper understanding of the quantum effects. Besides its fundamental interest, the vibrational wave function mapping is shown to be useful for the analysis of core- and valence-excited molecular states based on the reflection principle. [ABSTRACT FROM AUTHOR]

Variable size neon clusters consisting mostly of surface sites are investigated in the Ne 2s regime (44-50 eV), which is characterized by Rydberg-/exciton-transitions. Distinct changes in peak shape are observed upon the transition from the atom to clusters as probed by yields of mass selected cations and threshold photoelectron spectra, where changes in coupling to the underlying 2p continuum are observed in clusters. Cluster size dependent changes in cation yields are observed and rationalized in terms of a plausible autoionization mechanism, which involves 2s ionization and is followed by charge delocalization via Interatomic Coulombic Decay (ICD). Size- and site-dependent changes in energy position of the Rydberg states as well as 2s ionization energy are also observed. These results are interpreted along with model calculations which allow us to assign the experimental results in greater detail. The experimental and theoretical results are also used to deduce the exchange interaction of the Rydberg electron with the surrounding atoms and the induced polarization of the surrounding atoms in small neon clusters. [ABSTRACT FROM AUTHOR]

Abstract: As a molecular carrier and storage protein, apolipoprotein (Apo) mediates the intracellular uptake of lipids, proteins, vitamins and carotenoids. In this study, we identified a novel Apo gene, designated hcApo, from the freshwater pearl mussel Hyriopsis cumingii. The complete hcApo cDNA consists of 4104 nucleotides with an open reading frame encoding 1155 amino acid residues. The hcApo protein contains a conserved lipoprotein N-terminal domain (LPD-N) that is a characteristic of the large lipid transfer protein (LLTP) superfamily. The hcApo mRNA is constitutively expressed in a wide range of tissues with the highest expression level in the liver. Moreover, differential expression analysis revealed that the hcApo gene is more highly expressed in the liver, kidney, mantle and gill of purple line mussels compared to white line mussels. In situ hybridization investigations of the precise expression site of hcApo mRNA in the mantle showed that hcApo mRNA is specifically expressed in the outer epithelial cells of the middle fold and the inner epithelial cells of the outer fold of the mantle, as well as throughout the outer epithelium of the outer fold and ventral mantle. Another very important finding is that significantly positive correlation existed between the hcApo gene expression level and the total carotenoid content in purple line mussels. These findings may provide a better understanding of the roles of hcApo in the molecular mechanisms of shell formation and coloring of H. cumingii. [Copyright &y& Elsevier]

Abstract: High-energy X-ray was irradiated to EuBa2Cu3Oy, which is one of the REBa2Cu3Oy (RE=rare earth) compounds, at low temperature (100K), and the electrical resistivity was measured in situ at the same temperature (100K). The X-ray energy was chosen near Cu K-edge (8.98keV), Eu L3-edge (6.98keV) and Ba L3-edge (5.25keV) so that the effect of inner-shell excitation can be detected, if any. The irradiation-induced increase in the electrical resistivity is observed during the irradiations with X-ray in the energy range of 5–9keV. The electrical resistivity monotonically increases as increasing photon dose. Even if the X-ray is switched off, the irradiation-induced effect remains unchanged. The observed effect has an opposite trend compared with that observed for the visible light irradiation which causes persistent photoconductivity. It is also found that the irradiation-induced increase in resistivity scales with the energy absorbed by EuBa2Cu3Oy. This result indicates that the relaxation process of the energy absorbed by EuBa2Cu3Oy dominates the resistivity increase. The ejection of inner-shell electrons is not the unique cause of the observed effect. The possible origin of the resistivity increase is discussed. [Copyright &y& Elsevier]

Abstract: The potential energy curves (PECs) have been calculated for the X1Σ+, A1Σ+, 13Σ+, 23Σ+ states of KLi using multireference configuration interaction method and large all-electron basis sets. The calculations take into account the effect of inner-shell electrons with different active spaces. The rotational and vibrational energy levels are obtained by solving the Schrödinger equation of nuclear motion based on the PECs. The spectroscopic parameters are determined from the rotational and vibrational levels and compared with the theoretical and experimental reports in the literature. The PECs are fitted into analytical potential energy functions using the Morse long-range potential function. The effect of inner-shell electrons on the PECs, rotational and vibrational energy levels and spectroscopic parameters is analyzed. [Copyright &y& Elsevier]

Highlights: [•] Fragmentation of aniline upon K-shell excitation/ionization was studied. [•] Main fragments were assigned with an isotopologue and by the MLR analysis. [•] The C3H3 + was a characteristic fragment ion at the N 1s edge. [•] The aniline molecular cation can isomerize prior to dissociation. [ABSTRACT FROM AUTHOR]

Abstract: Rapid energy-level shifts in metals due to intense near-edge photoexcitation of core electrons are investigated with the density matrix formalism. Analytic theory indicates that, as the core hole density increases, the core levels are lowered relative to the valence levels, leading to an enhancement of the band gap; its origin can be attributed to a large asymmetry between localized core and delocalized valence orbitals. The energy-level shifts are incorporated into the rate equation to compute time evolutions of near-edge photoabsorption spectra for metallic lithium irradiated by a vacuum ultraviolet laser pulse. Numerical results indicate saturable absorption due to a blue shift of the K-edge, leading to a nonlinear transmission of the laser pulse at high intensities. [Copyright &y& Elsevier]

The energy position and line shape of the 2t2g-shape resonance in X-ray absorption spectra near the S 2p edges is investigated for free molecular SF6 and molecular units that are bound in clusters. We apply the double-barrier optical potential model in order to derive relationships between the position and line shape of the shape resonance where both intramolecular S—F and intermolecular SF6—SF6 separations in clusters is considered. The model calculations indicate that these intra- and inter-molecular separations are sensitive parameters. The comparison of the experimental and theoretical results shows that slight changes in molecular and intermolecular geometry affect the energy position and the line shape of the 2t2g-shape resonance in clusters. Processes affecting the line shape are discussed. It is found that the zero-point intramolecular motion leads to a noticeable broadening of the adiabatic 2t2g-shape resonance in free molecules and that the zero-point intermolecular motion also broadens the shape resonance in clustered molecules. [Copyright &y& Elsevier]

Oscillator strengths for N 1s excitation spectra of the gas-phase aniline and nitrobenzene, and the solid-phase meta- and para-nitroanilines have been derived from the total electron yield and total ion yield spectra acquired by tunable synchrotron radiation. Ab initio calculations carried out within the improved virtual orbital method and equivalent ionic core virtual orbital model have been used to aid spectral interpretation. The Rydberg-valency mixture has also been evaluated for all compounds. These results are compared to those acquired with the extended hückel molecular orbital method [Goeta et al., Chem Mater, 2000, 12, 3342]. The building block model has been used to simulate the nitroanilines spectra. The sensitivity of core excitation spectroscopy to intramolecular nitroanilines charge transfer and the N 1s → π* spectral features dependence upon the substitution pattern (meta or para) have been confirmed, as already verified for the gas-phase inner-shell energy loss spectra for the same molecules [Turci et al., Can J Chem, 1996, 74, 851]. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [ABSTRACT FROM AUTHOR]

Abstract: We have investigated photon-stimulated ion desorption from deuterated benzene (C6D6) adsorbed on Si(100) and Si(111) surfaces following C 1s core excitation. Using time-of-flight mass spectrometry combined with angle-dependent technique, we measured the dependences of mass-spectra of desorption ions on photon energies and on incident angle (θ) of synchrotron beam. We have found the ion yields for adsorbate-derived fragments of CD+ and CD2 + are enhanced in very small angles of incident X-rays. Moreover, molecular orientation effect appeared in excitation energy dependences of D+ ions from the Si(100) and Si(111) surfaces; that is, ion yield spectra measured at θ =10° are different from that at θ =65°. Furthermore, it was found that desorption ion yields increase greatly with decreasing incident angles. The angular dependences are consistently similar for all ion species, excitation energies, and indexes of substrates. Possible desorption processes are described on the basis of the observations. [Copyright &y& Elsevier]

Abstract: The results of studies of the time-resolved luminescence of self-trapped excitons (STE) with different multiplicity as well as the X-ray emission in oriented BeO crystals under excitation in the vicinity of the 1s Be photoabsorption edge are presented. The branching of the electronic excitations relaxation depends strongly on the crystal orientation after the inner-shell excitation. The common features between the processes of the STE luminescence and resonantly excited X-ray fluorescence have been discussed. [Copyright &y& Elsevier]

Abstract: Electron energy loss spectra of gas phase carbon disulfide have been recorded under dipole and strongly non-dipole conditions in the region of S 2p, and C 1s excitation. Inner-shell triplet states have also been observed by measuring near threshold C 1s energy loss spectra using a wide range of angles (4–20°) and impact energies (130–1300eV). The optical oscillator strength (OOS) and generalized oscillator strength profiles (GOS) have been calculated for vertical excitation from the ground electronic state to several C(1s) and S(2p) inner-shell electronic excited states of CS2 molecule, using high level ab initio (HF-CI) calculations. [Copyright &y& Elsevier]

Abstract: Beryllium oxide (BeO) crystals were investigated by time-resolved low temperature VUV-spectroscopy at the SUPERLUMI station and BW3 beam line of HASYLAB (DESY, Hamburg). Photoluminescence spectra (3–10.5eV), luminescence decay kinetics upon selective photoexcitation, as well as luminescence excitation (50–650eV) and reflectivity (9–35eV) spectra were measured and analyzed for oriented BeO crystals. It was shown that study of oriented crystals makes the traditional time-resolved spectroscopy method essentially more informative. Formation of the self-trapped exciton excited states of different multiplicity was found to sensitively depend on excitation energy and mutual orientation of the crystal''s C optical axis and electric vector E of exciting polarized synchrotron radiation. [Copyright &y& Elsevier]

Abstract: Time-resolved soft X-ray and vacuum ultraviolet fluorescence resulting from the decay processes of 2p inner-shell excited Ar clusters has been observed. Fluorescence with 3–10ns lifetime is observed, and assigned as being cluster-specific. This fluorescence can be attributed to arising from the decay of excited states of either neutral or singly ionized atoms produced via energy transfer or electron transfer processes including the interatomic Coulombic decay mechanism. The time-uncorrelated neutral yield spectra arise from large Ar clusters. [Copyright &y& Elsevier]

Abstract: The generalized oscillator strength profiles in the momentum transfer range (K) of (2a.u.−2 < K 2 <30a.u.−2) for the most intense resolved S 2p, and C 1s transitions of carbon disulfide (CS2) are presented. Optical oscillator strengths and generalized oscillator strength profiles have been calculated for vertical excitation from the ground electronic state to several C(1s) and S(2p) inner-shell electronic excited states of CS2, using high level ab initio (HF-CI) calculations. The experimental and computed GOS profiles of CS2 are compared and found to be generally in reasonable agreement. [Copyright &y& Elsevier]

Abstract: Time of flight mass spectrometry with multi-ion coincidence detection has been used to investigate ionic photofragmentation of four isotopes of gaseous formic acid [HCOOH, HCOOD, DCOOH and DCOOD] following C 1s excitation and ionization. C 1s spectra, branching ratios and quantitative yields of ions and ion pairs are reported. For equivalent ionic decay channels in the four isotopes the partial ion and ion pair yield spectra are very similar. These gas phase results are compared to results from photon stimulated ion desorption (PSID) of deuterated formate adsorbed on Si(100) [H. Ikeura-Sekiguchi, T. Sekiguchi, K. Tanaka, Phys. Rev. B 53 (1996) 12655] where there is a very strong enhancement of the D+ yield at resonance and the COD+ yield at the resonance. Such enhancements were not observed in the fragmentation of gas phase formic acid. From this we conclude that these very specific bond breaking processes in surface adsorbed formate are associated with a minority channel such as a (2h, 1e) spectator Auger process, which becomes prominent through elimination of the dominant molecular fragmentation mechanisms by electronic recombination. [Copyright &y& Elsevier]

Abstract: We investigated photon-stimulated ion desorption (PSID) from solid MoO3 following Mo 3p1/2, 3p3/2 and O 1s inner-shell excitations. The photon-energy dependences of O+ ion desorption yields were measured using quadrupole mass spectrometry. Near-edge X-ray absorption fine structure (NEXAFS) spectra were measured by the total electron yield method and were compared with the desorption yield curves. Relatively high desorption yields were observed in O 1s→eg resonance compared with that in O 1s→t2g resonance, while no enhanced yields were observed in either the Mo 3p1/2 or Mo 3p3/2 edge. The enhancement effect in the O 1s→eg resonance was attributed to fast bond breakage induced by the antibonding nature of the σ∗-like eg orbital. On the other hand, the non-enhancement following the Mo 3p1/2 and 3p3/2 edges was ascribed to the de-excitation of the excited electrons via very fast Coster–Kronig transitions, which can take place only following Mo 3p1/2 and 3p3/2 excitations. [Copyright &y& Elsevier]

Abstract: A general expression for the differential cross section of dielectronic recombination (DR) of polarized electrons and polarized ions is derived by using usual atomic theory methods and is represented in the form of multiple expansions over spherical tensors. The ways of the application of the general expressions suitable for the specific experimental conditions are outlined by deriving asymmetry parameters of angular distribution of DR radiation in the case of non-polarized and polarized ions and electrons. [Copyright &y& Elsevier]

In order to investigate the soft X-ray energy transformation in oxide detectors the optical spectra of several wide-gap oxide crystals were analyzed. The time-resolved luminescence (2.5–10.5 eV) and luminescence excitation spectra (50–200 and 500–630 eV) as well as decay kinetics of luminescence at 10 and 295 K were recorded using the synchrotron radiation from BW3 channel (HASYLAB, DESY). Several analogous features were discovered in the excitation spectra of both intrinsic self-trapped exciton luminescence and recombination luminescence for BeO, BeAl2O4, Be2SiO4 and AlPO4 crystals under inner-shell excitation. Simultaneously, the excitation of Ce3+-luminescence in scintillating Be2La2O5-Ce crystals significantly differs. [Copyright &y& Elsevier]

Ionic photofragmentation of carbon monoxide following carbon 1s and oxygen 1s excitation has been measured quantitatively with tuned synchrotron light and time-of-flight mass spectrometry using a Wiley–McLaren apparatus modified with an additional ion lens for improved quantitative performance. The sensitivity of the apparatus to kinetic energy and angular distribution effects has been characterized for selected lens settings through ion trajectory simulations and experimental measurements. Three distinct modes of the added lens have been identified (focus, defocus, and maximum). The focus mode has the least sensitivity to details of the angular and ion kinetic energy distribution and, therefore, is the best mode for measuring quantitative partial ion and ion-pair yields. The defocus mode has the most sensitivity to angular and kinetic energy distributions and, therefore, is the mode that provides the most information about the kinematics of photofragmentation. Branching ratios for ion and ion-pair production in all positive ion fragmentation channels were recorded from 280 to 330 eV (C 1s) and from 520 to 570 eV (O 1s) in the "focus" mode. Quantitative oscillator strengths were derived by combining these branching ratios with absolute total ion yield spectra. The results are compared to literature values. [ABSTRACT FROM AUTHOR]

Recent theoretical and experimental work on the photodetachment of C−, B−, and Li− is reviewed, with emphasis on the dominant shape resonance behavior above the K-shell thresholds. Of particular importance, the interaction between low-energy photoelectrons and Auger electrons is found to deplete the measured yield of positive ions near threshold for Li− (although not for C− and B−). A fully quantum mechanical modification of the R-matrix method is introduced to include the recapture of slow photoelectrons following Auger decay of an inner-shell vacancy state and is applied to the photodetachment of Li− above the 1s−1 threshold. The result show excellent agreement with experiment and resolve a large discrepancy in the cross section near the 1s threshold between theory and experiment. [Copyright &y& Elsevier]

One ionization mechanism of barium ions is the resonant excitation of a 3d inner-shell electron with the subsequent decay of the resulting highly excited intermediate state by multiple autoionization processes. We have experimentally studied this process by observing associated resonance structures – in the energy range 700–800 eV – in the multiple (up to sevenfold) ionization cross-sections of Baq+ ions with 1&les;q&les;13. The 3d-resonance strength is determined quantitatively as a function of initial and final ion charge state. The results suggest a statistical description of multiple ionization via the excitation of inner-shell electrons. [Copyright &y& Elsevier]

Luminescence properties of pure and doped MgO and Al2O3 single crystals were investigated under excitation by extreme ultraviolet radiation covering the L- and K-absorption edges of cations (Mg, Al) and anion (O), respectively. The excitation spectra of intrinsic and extrinsic emissions are antibate with respect to the absorption at the L-edges in both materials as well as at oxygen K-edge in Al2O3. Such behaviour is explained by non-radiative decay of electronic excitations at the surface. However, the efficiency of free exciton emission (7.6–7.7 eV) shows a positive jump at the oxygen K-edge whereas the recombination impurity emission at 5.4 eV has normal antibate behaviour with respect to the absorption in MgO. The origin of these effects is discussed. [Copyright &y& Elsevier]

Dissociative multiple photoionization of iodotrimethylsilane [(CH3)3SiI] has been investigated in the I(4d), Si(2p), I(4p), I(4s), C(1s), I(3p), and I(3d) core level excitation/ionization regions in the range from 88 to 1000 eV by time-of-flight (TOF) mass spectrometry and the photoion–photoion coincidence (PIPICO) method coupled to synchrotron radiation. The inner-shell spectra below 160 eV are dominated by a powerful giant resonance which has been identified as a resonance owing to the diffusion of the outgoing photoelectrons by the centrifugal barrier in the I(4d9∊f) outgoing channel. In addition to the huge resonance, discrete photoabsorption bands around the Si(2p) (106.77 eV) and the C(1s) (289.95 eV) edges are observed in both the total photoion and PIPICO yield spectra. Site-selective dissociation patterns were elucidated by the coincident measurements of the fragment ions formed via a single photon absorption. At low energies below the Si(2p) threshold region (88–107 eV), dissociation pathways leading to the formation of H+–I2+ and H+–I+ are dominant. Above the energy, however, near total destruction giving rise to CH3+–SiH+, H+–CHp+ (p=0–3), H+–SiHp+ (p=0–3), SiCHn+–I+, and H+–SiCHp+ (p=0–5) are dominant. [Copyright &y& Elsevier]