The pyramid wavefront sensor is very similar to the Fourier knife-edge test, but employs dynamic modulation to quantify the phase derivative. For circular modulation, we compare approximate geometrical optics calculations, more exact diffraction calculations, and experimental results. We show that both the sinusoidal and the approximate linear relationship between wavefront derivative and wavef...

We report a flux crystal growth of Ba2[(UO2)2Ti2O8] and subsequent structural spectroscopic studies using multiple techniques. The layered structure, built up with sheets edge-sharing dimeric uranyl pentagonal bipyramids TiO5 square pyramids interlayer Ba(II) ions, was revealed by synchrotron single x-ray diffraction confirmed electron transmission microscope. presence only hexavalent uranium b...

für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution 4.0 International License. Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Creative Commons Namen...

Abstract The edge detection of microstructures by microscopes is poor in resolution due to the effect of diffraction limit. This paper proposes a new technique by using the focus probe in association with a nanopositioning stage. The edge is detected by the total energy reflection principle and the step height is detected by the astigmatic principle. Both methods can realize the resolution of 1...

Because of their intense white lines and large f" values, lanthanide atoms are of great interest for solving structures of biological macromolecules using single-wavelength anomalous diffraction (SAD) or multiple-wavelength anomalous diffraction (MAD) methods. In this work, a series of seven gadolinium complexes are described which provide excellent derivatives for anomalous diffraction experim...

An exact form for the equivalent edge current is derived by using the axioms of the modified theory of physical optics and the canonical problem of half-plane. The edge current is expressed in terms of the parameters of incident and scattered rays. The analogy of the method with the boundary diffraction wave theory is put forward. The edge and corner diffracted waves are derived for the problem...

Let G and H be graphs. As usual, we say that H is a minor or subcontraction of G if V(G) contains disjoint subsets Wu , u # V(H), such that G[Wu] is connected for each u # V(H) and there is an edge in G between Wu and Wv whenever uv # E(H). (Here, G[Wu] stands for the subgraph of G induced by Wu ; our notation is standard and follows that of Bolloba s [2].) We write GoH if H is a minor of G, an...

The secondary edge source line integral formulation for diffraction modeling uses edge sources with a 1/r dependency, in addition to a directivity function. At first sight, this might seem to contradict the expected 1/r behavior for the gradient near the edge of a thin screen. An analysis is presented for the special case of perpendicular plane wave incidence onto a thin screen, which shows tha...

X-ray absorption spectroscopy is exquisitely sensitive to the coordination geometry of an absorbing atom and therefore allows bond distances and angles of the surrounding atomic cluster to be measured with atomic resolution. By contrast, the accuracy and resolution of metalloprotein active sites obtainable from x-ray crystallography are often insufficient to analyze the electronic properties of...