Theoretical investigation of the halogen bonded complexes between carbonyl bases and molecular chlorine

The halogen bonded complexes between six carbonyl bases and molecular chlorine are investigated theoretically. The interaction energies calculated at the CCSD(T)/aug‐cc‐pVTZ level range between ?1.61 and ?3.50 kcal mol^?1. These energies are related to the ionization potential, proton affinity, and also to the most negative values (V_s,min) on the electrostatic potential surface of the carbonyl bases. A symmetry adapted perturbation theory decomposition of the energies has been performed. The interaction results in an elongation of the Cl? Cl bond and a contraction of the CF and CH bonds accompanied by a blue shift of the ν(CH) vibrations. The properties of the Cl₂ molecules are discussed as a function of the σ*(Cl? Cl) occupation, the hybridization, and the occupation of the Rydberg orbitals of the two chlorine atoms. Our calculations predict a large enhancement of the infrared and Raman intensities of the ν(Cl? Cl) vibration on going from isolated to complexed Cl₂. © 2015 Wiley Periodicals, Inc.     

3D Velocimetry and droplet sizing in the Ranque–Hilsch vortex tube

The Ranque–Hilsch vortex tube (RHVT) is a device currently used to generate local cooling. In general, the fluid that is injected into the RHVT is a single-phase gas. In this study, however, we have added a dispersed phase (water droplets) to the gas (nitrogen). By means of phase Doppler particle analysis, three velocity components, their higher order moments, and sizes of droplets were measured, showing high intensity velocity fluctuations in the core region of the main vortex. The frequency spectrum of the velocity is presented and reveals that wobbling of the vortex axis is the cause of the high intensity fluctuations. The wobbling motion reduces the influence of the droplet size on the radial droplet velocity.     

Preparation and characterization of MgB2 superconductor

The MgB₂ superconductor, synthesized using solid-state and liquid-phase sintering methods, have been characterized for various properties. The upper critical field, irreversibility line and critical current density have been determined using magnetization data. The current-voltage characteristics recorded under an applied magnetic field revealed the existence of vortex glass transition. The surface analysis using X-ray photoelectron spectroscopy shows that MgB₂ is sensitive to atmospheric degradation.