Photoemission core-level shifts reveal the thiolate-Au(111) interface

The nature of the thiolate/Au(111) interface is a long-standing puzzle. It has been suggested that thiolates drive surface reconstruction, however, a consensus regarding the adsorption configuration is missing. Herein, the density-functional theory is used to evaluate surface core-level shifts (SCLSs) for methyl thiolates on Au(111) assuming a representative set of different surface reconstructions. The SCLSs are found to provide sensitive fingerprints of the anchoring configuration, and it is only thiolate adsorption in the form of MeS-Au-SMe complexes that can be reconciled with experimental data

An evaluation of the Islington community education provider network super hub.

‘Super Hubs’ are novel initiatives which have arisen in order to aid various workforce developments and service improvements for promoting creative thinking and practice. The Islington Super Hub is a workstream of the Islington Community Education Provider Network (CEPN) which aids the learning and development of community nursing and new apprenticeships (Health Education North Central and East London 2015). In this paper we report on the findings from a realist evaluation of the Islington Super Hub (Pawson and Tilley 1997) using data from a range of provider organisations. The following areas of direct relevance to the Super Hub’s activity will be analysed: i) the factors enabling nursing staff to transfer between sectors; ii) the variety of current preceptorship and induction programmes supporting newly registered nurses moving into community roles; iii) the current links between primary/secondary care for strengthening inter-sectoral working and the core training needed for hospital-based nurses to support patient journeys; iv) the practice learning experiences of specialist practice community nurses, such as General Practice Nurses, District Nurses and Health Visitors as well as non-specialist practitioners and health care assistants; v) the current approaches for sustaining practice-based learning for enhanced learning/development; vi) the current approaches to multi-professional education across localities which contribute to establishing robust community focussed multi-professional collaborative educational approaches; vii) the availability of student nurse placements in community settings and the associated mentorship capacity. Our analysis concludes with critical reflection on the relative merits of the Super Hub’s programme of learning and development which aims to promote creative thought/practice and the contextual factors surrounding the newly emerging apprenticeship roles. References Health Education North Central and East London (2015) Nursing and Midwifery Education Strategy. London: Health Education North Central and East London. Pawson R, Tilley N (1997) Realistic Evaluation. London: Sag

An evaluation of the Islington community education provider network super hub

‘Super Hubs’ are novel initiatives which have arisen in order to aid various workforce developments and service improvements for promoting creative thinking and practice. The Islington Super Hub is a workstream of the Islington Community Education Provider Network (CEPN) which aids the learning and development of community nursing and new apprenticeships (Health Education North Central and East London 2015). In this paper we report on the findings from a realist evaluation of the Islington Super Hub (Pawson and Tilley 1997) using data from a range of provider organisations. The following areas of direct relevance to the Super Hub’s activity will be analysed: i) the factors enabling nursing staff to transfer between sectors; ii) the variety of current preceptorship and induction programmes supporting newly registered nurses moving into community roles; iii) the current links between primary/secondary care for strengthening inter-sectoral working and the core training needed for hospital-based nurses to support patient journeys; iv) the practice learning experiences of specialist practice community nurses, such as General Practice Nurses, District Nurses and Health Visitors as well as non-specialist practitioners and health care assistants; v) the current approaches for sustaining practice-based learning for enhanced learning/development; vi) the current approaches to multi-professional education across localities which contribute to establishing robust community focussed multi-professional collaborative educational approaches; vii) the availability of student nurse placements in community settings and the associated mentorship capacity. Our analysis concludes with critical reflection on the relative merits of the Super Hub’s programme of learning and development which aims to promote creative thought/practice and the contextual factors surrounding the newly emerging apprenticeship roles

The structure of the Au(111)/methylthiolate interface : new insights from near-edge X-ray absorption spectroscopy and X-ray standing waves

The local structure of the Au(111)([square root of]3×[square root of]3)R30°-methylthiolate surface phase has been investigated by S K-edge near-edge s-ray absorption fine structure (NEXAFS) both experimentally and theoretically and by experimental normal-incidence x-ray standing waves (NIXSW) at both the C and S atomic sites. NEXAFS shows not only excitation into the intramolecular sigma* S–C resonance but also into a sigma* S–Au orbital perpendicular to the surface, clearly identifying the local S headgroup site as atop a Au atom. Simulations show that it is not possible, however, to distinguish between the two possible adatom reconstruction models; a single thiolate species atop a hollow-site Au adatom or a dithiolate moiety comprising two thiolate species bonded to a bridge-bonded Au adatom. Within this dithiolate moiety a second sigma* S–Au orbital that lies near parallel to the surface has a higher energy that overlaps that of the sigma* S–C resonance. The new NIXSW data show the S–C bond to be tilted by 61° relative to the surface normal, with a preferred azimuthal orientation in , corresponding to the intermolecular nearest-neighbor directions. This azimuthal orientation is consistent with the thiolate being atop a hollow-site Au adatom, but not consistent with the originally proposed Au-adatom-dithiolate moiety. However, internal conformational changes within this species could, perhaps, render this model also consistent with the experimental data

Coupling methylammonium and formamidinium cations with halide anions: Hybrid orbitals, hydrogen bonding, and the role of dynamics

The electronic structures of four precursors for organic–inorganic hybrid perovskites, namely, methylammonium chloride and iodide, as well as formamidinium bromide and iodide, are investigated by X-ray emission (XE) spectroscopy at the carbon and nitrogen K-edges. The XE spectra are analyzed based on density functional theory calculations. We simulate the XE spectra at the Kohn–Sham level for ground-state geometries and carry out detailed analyses of the molecular orbitals and the electronic density of states to give a thorough understanding of the spectra. Major parts of the spectra can be described by the model of the corresponding isolated organic cation, whereas high-emission energy peaks in the nitrogen K-edge XE spectra arise from electronic transitions involving hybrids of the molecular and atomic orbitals of the cations and halides, respectively. We find that the interaction of the methylammonium cation is stronger with the chlorine than with the iodine anion. Furthermore, our detailed theoretical analysis highlights the strong influence of ultrafast proton dynamics in the core-excited states, which is an intrinsic effect of the XE process. The inclusion of this effect is necessary for an accurate description of the experimental nitrogen K-edge X-ray emission spectra and gives information on the hydrogen-bonding strengths in the different precursor materials

High resolution x ray spectra of carbon monoxide reveal ultrafast dynamics induced by long UV pulse

In theoretical simulations of a UV x ray pump probe UVX PP setup, we show that frequency detuning of the pump UV pulse acts as a camera shutter by regulating the duration of the UVX PP process. This two photon absorption with long overlapping UV and x ray pulses, allowing for high spectral resolution, thereby provides information about ultrafast dynamics of the nuclear wave packet without the requirement of ultrashort pulses and controlled delay times. In a case study of carbon monoxide, the calculated UVX PP spectra of the O1s amp; 8722;12 amp; 960;1 and C1s amp; 8722;12 amp; 960;1 core excited states show different vibrational profiles. The interference of intermediate vibrational states reveals details of nuclear dynamics in the UVX PP process related to a variable duration time controlled by the UV detuning. Both O1s amp; 8722;12 amp; 960;1 and C1s amp; 8722;12 amp; 960;1 pump probe channels display a splitting of the spectral profile, which however is associated with different physical mechanisms. At the O1s amp; 8722;12 amp; 960;1 resonance, the observed dispersive and non dispersive spectral bands intersect and result in destructive interferenc

Carbon K-edge x-ray emission spectroscopy of gas phase ethylenic molecules

We report on the C K-edge x-ray absorption spectra and the resonant (RXES) and non-resonant (NXES) x-ray emission spectra of ethylene, allene and butadiene in the gas phase. The RXES and NXES show clear differences for the different molecules. Overall both types of spectra are more structured for ethylene and allene, than for butadiene. Using density functional theory–restricted open shell configuration interaction single calculations, we simulate the spectra with remarkable agreement with the experiment. We identify the spectral features as being due to transitions involving localised 1s orbitals. For allene, there are distinct spectral bands that reflect transitions predominantly from either the central or terminal carbon atoms. These results are discussed in the context of ultrafast x-ray studies aimed at detecting the passage through conical intersections in polyatomic molecules

Ab initio van der Waals interactions in simulations of water alter structure from mainly tetrahedral to high-density-like

The structure of liquid water at ambient conditions is studied in ab initio molecular dynamics simulations using van der Waals (vdW) density-functional theory, i.e. using the new exchange-correlation functionals optPBE-vdW and vdW-DF2. Inclusion of the more isotropic vdW interactions counteracts highly directional hydrogen-bonds, which are enhanced by standard functionals. This brings about a softening of the microscopic structure of water, as seen from the broadening of angular distribution functions and, in particular, from the much lower and broader first peak in the oxygen-oxygen pair-correlation function (PCF), indicating loss of structure in the outer solvation shells. In combination with softer non-local correlation terms, as in the new parameterization of vdW-DF, inclusion of vdW interactions is shown to shift the balance of resulting structures from open tetrahedral to more close-packed. The resulting O-O PCF shows some resemblance with experiment for high-density water (A. K. Soper and M. A. Ricci, Phys. Rev. Lett., 84:2881, 2000), but not directly with experiment for ambient water. However, an O-O PCF consisting of a linear combination of 70% from vdW-DF2 and 30% from experiment on low-density liquid water reproduces near-quantitatively the experimental O-O PCF for ambient water, indicating consistency with a two-liquid model with fluctuations between high- and low-density regions