Sequential and Direct Two-Photon Double Ionization of D₂ at Flash

Sequential and direct two-photon double ionization (DI) of D2 molecule is studied experimentally and theoretically at a photon energy of 38.8 eV. Experimental and theoretical kinetic energy releases of D++D+fragments, consisting of the contributions of sequential DI via the D2+(1sσg) state and direct DI via a virtual state, agree well with each other

Vibrationally resolved B 1s photoionization cross section of BF3

We present a study of the vibrationally resolved B 1s photoionization cross section of the BF 3 molecule. A combination of high-resolution photoelectron spectroscopy measurements and of state-of-the-art calculations shows the evolution of the photon energy dependence of the cross section from a complete trapping of the photoelectron wave (low energies) to oscillations due to intramolecular scattering. These diffraction patterns allow to access structural information of both the neutral molecule and the core -hole species generated upon photoabsoptio

Simple scoring system to predict in-hospital mortality after surgery for infective endocarditis

BACKGROUND: Aspecific scoring systems are used to predict the risk of death postsurgery in patients with infective endocarditis (IE). The purpose of the present study was both to analyze the risk factors for in-hospital death, which complicates surgery for IE, and to create a mortality risk score based on the results of this analysis. METHODS AND RESULTS: Outcomes of 361 consecutive patients (mean age, 59.1\ub115.4 years) who had undergone surgery for IE in 8 European centers of cardiac surgery were recorded prospectively, and a risk factor analysis (multivariable logistic regression) for in-hospital death was performed. The discriminatory power of a new predictive scoring system was assessed with the receiver operating characteristic curve analysis. Score validation procedures were carried out. Fifty-six (15.5%) patients died postsurgery. BMI >27 kg/m2 (odds ratio [OR], 1.79; P=0.049), estimated glomerular filtration rate 55 mm Hg (OR, 1.78; P=0.032), and critical state (OR, 2.37; P=0.017) were independent predictors of in-hospital death. A scoring system was devised to predict in-hospital death postsurgery for IE (area under the receiver operating characteristic curve, 0.780; 95% CI, 0.734-0.822). The score performed better than 5 of 6 scoring systems for in-hospital death after cardiac surgery that were considered. CONCLUSIONS: A simple scoring system based on risk factors for in-hospital death was specifically created to predict mortality risk postsurgery in patients with IE

Vibrational branching ratios in the photoelectron spectra of N2 and CO: interference and diffraction effects

We present a detailed account of existing theoretical methods specially designed to provide vibrationally resolved photoionization cross sections of simple molecules within the Born-Oppenheimer approximation, with emphasis on newly developed methods based on density functional theory. The performance of these methods is shown for the case of N 2 and CO photoionization. Particular attention is paid to the region of high photon energies, where the electron wavelength is comparable to the bond length and, therefore, two-center interferences and diffraction are expected to occur. As shown in a recent work [Canton et al., Proc. Natl. Acad. Sci. U. S. A., 2011, 108, 7302-7306], the main experimental difficulty, which is to extract the relatively small diffraction features from the rapidly decreasing cross section, can be easily overcome by determining ratios of vibrationally resolved photoelectron spectra and existing theoretical calculations. From these ratios, one can thus get direct information about the molecular geometry. In this work, results obtained in a wide range of photon energies and for many different molecular orbitals of N 2 and CO are discussed and compared with the available experimental measurements. From this comparison, limitations and further possible improvements of the existing theoretical methods are discussed. The new results presented in the manuscript confirm that the conclusions reported in the above reference are of general validityWe thank Mare Nostrum BSC, Cineca and CCC-UAM for allocation of computer time. Work supported by the MICINN project Nos. FIS2010-15127, ACI2008-0777 and CSD 200700010 (Spain), the ERA-Chemistry project PIM2010EEC00751, the European COST Action CM0702, the Marie Curie ITN CORINF (EU), and the XCHEM Advanced Grant 290853 of the European Research Counci

Vibrationally-resolved photoelectron angular distributions from randomly-oriented and fixed-in- space N2 and CO molecules

This is an author-created, un-copyedited version of an article published in Journal of physics B: atomic molecular and optical physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0953-4075/45/19/194008Vibrationally resolved photoelectron angular distributions from randomly oriented and fixed-in-space N 2 and CO molecules have been evaluated by using an extension of the static-exchange density functional theory that includes the nuclear motion. Both K-shell and valence-shell photoionization have been considered. Comparison with the experimental data, only available for randomly oriented molecules, is very good. Our predictions for molecular-frame photoelectron angular distributions of N 2 show the signature of electron confinement and coherent two-centre interferences as those previously found in H 2. For CO, they exhibit diffraction patterns associated with the scattering of the ejected electron by the neighbouring atomic centre. The conclusions reported in this work suggest that vibrationally resolved photoelectron angular distributions can be a useful instrument to determine structure parameters in these simple moleculesWe thank Mare Nostrum BSC, Cineca and CCC-UAM for allocation of computer time. Work supported by the MICINN project Nos. FIS2010-15127, ACI2008-0777 and CSD 2007-00010 (Spain), the ERA-Chemistry project PIM2010EEC-00751, the European COST Action CM0702, the Marie Curie ITN CORINF, and the XCHEM Advanced Grant 290853 of the European Research Counci

Direct observation of Young\u2019s double-slit interferences in vibrationally resolved photoionization of diatomic molecules

Vibrationally resolved valence-shell photoionization spectra of H2, N2 and CO have been measured in the photon energy range 20\u2013300 eV using third-generation synchrotron radiation. Young\u2019s double-slit interferences lead to oscillations in the corresponding vibrational ratios, showing that the molecules behave as two-center electron-wave emitters and that the associated interferences leave their trace in the angle-integrated photoionization cross section. In contrast to previous work, the oscillations are directly observable in the experiment, thereby removing any possible ambiguity related to the introduction of external parameters or fitting functions. A straightforward extension of an original idea proposed by Cohen and Fano [Cohen HD, Fano U (1966) Phys Rev 150:30] confirms this interpretation and shows that it is also valid for diatomic heteronuclear molecules. Results of accurate theoretical calculations are in excellent agreement with the experimental findings

Cluster approach to scattering in MoS2 photoemission

We examine the photoemission cross sections and Wigner time delays from MoS2 core-level orbitals Mo4s, Mo4p, S3s. We employ a cluster approach and study the photoemission process for progressively larger model clusters, in order to assess the scattering effects by neighboring atoms. First we explore how the fully differential cross section (FDCS) from the localized orbitals evolves as we increase the cluster size. In order to establish the underlying scattering mechanics that are mapped into the FDCS and Wigner time delays, we jointly analyze them in terms of the polar emission angle and photoemission energy for fixed azimuthal angles. The Wigner-time-delay scale goes from a few tens up into the hundreds of attoseconds when increasingly large clusters are considered, indicating the presence of high order scattering processes and interference. We find that, for the largest clusters, some internal propagation pathways start taking shape, which in an infinite system would amount to band structure positive energy states. We conclude that second- or higher-order neighbors around the main emitter strongly affect the photoelectron propagation and yield, therefore supporting their importance for models that aim for quantitative descriptions.This work has been supported in part by the Basque Departamento de Educación, Universidades e Investigación, the University of the Basque Country UPV/EHU (Grant No. IT1246-19) and the Spanish Ministerio de Ciencia e Innovación projects PID2019-107396 GB-I00 and PID2019-105458RB-I00, the ’Severo Ochoa’ Programme for Centres of Excellence in R&D (SEV-2016–0686), and the ’María de Maeztu’ Programme for Units of Excellence in R&D (CEX2018-000805-M). We acknowledge the computation time awarded to this research on MareNostrum 4 cluster, QS-2021–1-0037,QS-2020–3-0036, FI-2020–2-0007, FI-2020–1-0009, and the Centro de Computación Científica (CCC) of Universidad Autónoma de Madrid.Peer reviewe

Scattering effects from neighboring atoms in core-level WSe2 photoemission

Methods of attosecond science originally developed to investigate systems in the gas phase are currently being adapted to obtain temporal information on the electron dynamics that takes place in condensed-matter systems. In particular, streaking measurements have recently been performed to determine photoemission time delays from the WSe2 dichalcogenide. In this work we present a fully atomistic description of the photoemission process in WSe2 and provide angularly resolved photoemission cross sections and time delays from the W 4f, Se 3d and Se 4s core states of the system. Since these states are spatially localized, we propose a cluster approach in which we build up from smaller to larger clusters, so that we can assess the importance of scattering effects by each new layer of neighboring atoms. We use a static-exchange density functional theory method with B-spline functions, where a one-center angular-momentum expansion is supplemented by off-center expansions with fewer partial waves. This enhances convergence in comparison with a one-center expansion, which would require very high angular momenta to characterize the localized fast oscillations near each off-center atomic core. We find that the photoemission delays and fully differential cross sections are strongly affected by scattering events that take place off the neighboring atoms, implying the need to consider their effects for quantitative descriptions of the photoemission process.This work has been supported in part by the Basque Departamento de Educación, Universidades e Investigación, the University of the Basque Country UPV/EHU (Grant No. IT1246-19) and the Spanish Ministerio de Ciencia e Innovación projects PID2019-107396GB-I00 and PID2019-105458RB-I00, the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2016-0686), and the “María de Maeztu” Programme for Units of Excellence in R&D (CEX2018-000805-M). We acknowledge the computation time awarded to this research on MareNostrum 4 cluster, QS2021-1-0037, QS-2020-3-0036, FI-2020-2-0007, FI-2020-1-0009, and the Centro de Computación Científica (CCC) of Universidad Autónoma de Madrid.Peer reviewe