Anomalous Workfunction Anisotropy in Ternary Acetylides

Anomalous anisotropy of workfunction values in ternary alkali metal transition metal acetylides is reported. Workfunction values of some characteristic surfaces in these emerging semiconducting materials may differ by more than $\approx$ 2 eV as predicted by Density Functional Theory calculations. This large anisotropy is a consequence of the relative orientation of rod-like [MC$_{2}$]$_{\infty}$ negatively charged polymeric subunits and the surfaces, with M being a transition metal or metalloid element and C$_{2}$ refers to the acetylide ion C$_{2}^{2-}$, with the rods embedded into an alkali cation matrix. It is shown that the conversion of the seasoned Cs$_{2}$Te photo-emissive material to ternary acetylide Cs$_{2}$TeC$_{2}$ results in substantial reduction of its $\approx$ 3 eV workfunction down to 1.71-2.44 eV on the Cs$_{2}$TeC$_{2}$(010) surface while its high quantum yield is preserved. Similar low workfunction values are predicted for other ternary acetylides as well, allowing for a broad range of applications from improved electron- and light-sources to solar cells, field emission displays, detectors and scanners.Comment: Accepted for publication in Phys. Rev.

Analysis and Simulation of the Structure of Nanoparticles That Undergo a Surface-Driven Structural Transformation

This report addresses the analysis and simulation of the structure of nanoparticles that undergo a surface-driven structural transformation

X-ray resonant magnetic scattering study of magnetization reversals in a nanoscale spin-valve array

We present an x-ray resonant magnetic scattering study that uses the periodicity of a patterned array of trilayer (Co/Cu/NiFe) elements to determine not only layer-dependent magnetic hysteresis, but, more importantly, to extract the magnetization reversal in different sections of the picture-frame-shaped structure. Spatially resolved and layer-resolved magnetization measurements have revealed that magnetic switching mechanism is very distinct in different regions of the structure and results from a balancing of the shape anisotropy and strong interlayer dipolar coupling. These results demonstrate how spatially averaged measurements are not sufficient to resolve the nature of the reversal mechanism within the structure

The Influence of X-Rays on the Structural Studies of Peroxide-Derived Myoglobin Intermediates

In recent years, the awareness of potential radiation damage of metal centers in protein crystals during crystallographic data collection has received increasing attention. The radiation damage can lead to radiation-induced changes and reduction of the metal sites. One of the research fields where these concerns have been comprehensively addressed is the study of the reaction intermediates of the heme peroxidase and oxygenase reaction cycles. For both the resting states and the high-valent intermediates, the X-rays used in the structure determination have given undesired side effects through radiation-induced changes to the trapped intermediates. However, X-rays have been used to generate and trap the peroxy/hydroperoxy state in crystals. In this review, the structural work and the influence of X-rays on these intermediates in myoglobin are summarized and viewed in light of analogous studies on similar intermediates in peroxidases and oxygenases