Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.

The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project. ?? 2013 Elsevier B.V. All rights reserved

The first atomic images of the hydrogen terminated Si(111) surface have been acquired in aqueous sulfuric acid solutions. The observed interatomic distance with threefold symmetry is ∼3.8 Å, indicating that the ideal Si(111):H-1×1 surface can be prepared by chemical etching in NH4F solutions. It is demonstrated that in situ scanning tunneling microscopy is an extremely important method for revealing chemical processes with atomic resolution in the chemical etching of semiconductors in solutions.

Spiroconjugation, that is, through-space orbital interactions between two perpendicular π orbitals, is a key concept in the contemporary molecular design of spirocyclic π-electron systems. We synthesized spiropentasiladiene radical cation salt 1 as a dark-green solid via the one-electron oxidation of the stable spiropentasiladiene 2. Characterization of the molecular structure combined with theoretical studies indicated that the spin and positive charge are delocalized across the two perpendicular SiSi double bonds of 1. Two π­(SiSi) orbitals are split into HOMO and SOMO with a small energy gap owing to the second-order Jahn–Teller distortion and steric repulsion between bulky alkyl groups upon one-electron oxidation. In the UV–vis–NIR spectrum, the longest-wavelength absorption band of 1 (λmax = 1972 nm) covers the IR-B region (1400–3000 nm; 0.89–0.41 eV) despite having the smallest possible spiroconjugation motif. The unprecedented absorption band in the IR region was assigned to the HOMO → SOMO transition that arises from the delocalized π-orbitals in the spirocyclic Si5 skeleton.

Not so alkyne like: A dialkyldisilyne (left, green) that can be isolated is synthesized and fully characterized. It coordinates to palladium and platinum in a η(2) -fashion giving complexes (red) with a trans-bent geometry, in contrast to η(2) -alkyne complexes. The complexes showed significant metallacycle character.