Pixelated transmission‐mode diamond X‐ray detector

Fabrication and testing of a prototype transmission‐mode pixelated diamond X‐ray detector (pitch size 60–100 µm), designed to simultaneously measure the flux, position and morphology of an X‐ray beam in real time, are described. The pixel density is achieved by lithographically patterning vertical stripes on the front and horizontal stripes on the back of an electronic‐grade chemical vapor deposition single‐crystal diamond. The bias is rotated through the back horizontal stripes and the current is read out on the front vertical stripes at a rate of ～1 kHz, which leads to an image sampling rate of ～30 Hz. This novel signal readout scheme was tested at beamline X28C at the National Synchrotron Light Source (white beam, 5–15 keV) and at beamline G3 at the Cornell High Energy Synchrotron Source (monochromatic beam, 11.3 keV) with incident beam flux ranges from 1.8 × 10^?2 to 90 W mm^?2. Test results show that the novel detector provides precise beam position (positional noise within 1%) and morphology information (error within 2%), with an additional software‐controlled single channel mode providing accurate flux measurement (fluctuation within 1%).     

Semi-Focusing Billiards: Hyperbolicity

In this paper we answer affirmatively the question concerning the existence of hyperbolic billiards in convex domains of ℝ³. We also prove that a related class of semi-focusing billiards has mixed dynamics, i.e., their phase space is an union of two invariant sets of positive measure such that the dynamics is integrable on one set and is hyperbolic on the other. These billiards are the first rigorous examples of billiards in domains of ℝ³ with divided phase space. The first author was partially supported by the NSF grant #0140165 and the Humboldt Foundation. The second author was partially supported by the FCT (Portugal) through the Program POCTI/FEDER.     

Coordinative bond and d-shell ionisations in the UV photoelectron spectra of bis(β-diketonato) cobalt(II) and copper(II) complexes,and their thioanalogues

The analysis of UV photoelectron spectra of the title compounds, as well as of their Ni(II) analogues, is presented, with particular regard to the identification of d-ionisation bands. The spectra are assigned on the grounds both of a framework of interpretation similar to that usually applied to β-diketonato metal complexes, and of a systematic comparison between He(I) and He(II) data.     

New 4-spiroannulated tetrahydroisoquinolines by a one-pot sequential procedure. isolation and characterization of sigma-alkylpalladium heck intermediates

A simple and efficient entry to new tetrahydroisoquinolines 4-spiroannulated to a five-membered heterocyclic ring has been achieved starting from secondary N-allylamines and involving sequential 2-iodobenzylation/intramolecular Heck reaction/1,3-dipolar cycloaddition. A variety of Heck cyclization conditions were surveyed. When using Pd(PPh(3))(4) as catalyst, stable sigma-alkylpalladium iodide complexes were isolated and characterizated.     

beta-Pseudopeptide foldamers. The homo-oligomers of (4R)-(2-oxo-1,3-oxazolidin-4-yl)-acetic acid (D-Oxac)

A total synthesis in solution and a conformational analysis of the homo-oligomers of (4R)-(2-oxo-1,3-oxazolidin-4-yl)-acetic acid (D-Oxac) to the tetramer level are described. As the D-Oxac building block contains both an oxazolidin-2-one and a beta-amino acid group, it may represent a new type of conformationally constrained tool for the construction of beta-pseudopeptide foldamers. A conformational investigation using NMR and an extensive, unconstrained analysis with a Monte Carlo search to the octamer level, both in water and in chloroform, showed that these homo-oligomers tend to fold in a regular helical structure in a competitive solvent, such as water. Since aqueous solutions are of major relevance for biological systems, these molecules are good candidates for application to these environments.     

A full dynamical leed analysis of the NI(111) P(2 × 2)-C2H2 structure

The p(2 × 2) structure formed upon adsorption of acetylene on the Ni(111) surface, for 0.5 L exposure at 250 K, is studied by a full dynamical LEED analysis based on the comparison of only five I7ndash;V profiles at normal incidence. Among the several models tested, the most probable one is that with the adsorbed molecule parallel to the surface plane in a μ-bridging bonding site. The NiC distance is equal to 2.1 Å.     

Palladium-mediated approach to dibenzo[b,e][1,4]diazepines and benzopyrido-analogues. An efficient synthesis of tarpane

An original synthetic route toward dibenzo[b,e][1,4]diazepin-11-ones and analogues pyridobenzodiazepinones has been developed. The method relies upon an intramolecular amination process between an (hetero)aryl halide and the appropriate aniline moiety.