Freezing and melting of 3D complex plasma structures under microgravity conditions driven by neutral gas pressure manipulation

Freezing and melting of large three-dimensional complex plasmas under microgravity conditions is investigated. The neutral gas pressure is used as a control parameter to trigger the phase changes: Complex plasma freezes (melts) by decreasing (increasing) the pressure. The evolution of complex plasma structural properties upon pressure variation is studied. Theoretical estimates allow us to identify the main factors responsible for the observed behavior.     

Measurement of a large chemical reaction rate between ultracold closed-shell 40Ca atoms and open-shell 174Yb+ ions held in a hybrid atom-ion trap

Ultracold 174Yb+ ions and 40Ca atoms are confined in a hybrid trap. The charge exchange chemical reaction rate constant between these two species is measured and found to be 4 orders of magnitude larger than recent measurements in other heteronuclear systems. The structure of the CaYb+ molecule is determined and used in a calculation that explains the fast chemical reaction as a consequence of strong radiative charge transfer. A possible explanation is offered for the apparent contradiction between typical theoretical predictions and measurements of the radiative association process in this and other recent experiments.     

[4+2] Cycloaddition reactions of 1-alkyl-2,3,4,5-tetraphenylphosphole derivatives

Russian Chemical Bulletin - The [4+2] cycloaddition reactions of 1-alkyl-2,3,4,5-tetraphenylphosphole derivatives with N-phenylmaleimide were studied for the first time. The reactions of...     

Convenient synthesis of 6,7-dihydroazolo[5,1-b]quinazolin-8(5H)-one derivatives

Three-component condensation of 3(5)-aminoazoles with benzaldehydes and dimedone in acetonitrile in the presence of montmorillonite KSF as heterogeneous catalyst regioselectively afforded 5,6,7,9-tetrahydroazolo[5,1-b]quinazolin-8(4H)-one derivatives in good yields. Oxidation of the condensation products with ceric ammonium nitrate in acetone gave the corresponding 6,7-dihydroazolo[5,1-b]quinazolin-8(5H)-ones.     

Generalized relativistic effective core potential calculations of the adiabatic potential curve and spectroscopic constants for the ground electronic state of the Ca2 molecule

The potential curve, dissociation energy, equilibrium internuclear distance, and spectroscopic constants for the ground state of the Ca₂ molecule are calculated with the help of the generalized relativistic effective core potential method, which allows one to exclude the inner core electrons from the calculations and to take the relativistic effects into account effectively. Extensive generalized correlation basis sets were constructed and used. The scalar relativistic coupled cluster method with corrections for high‐order cluster amplitudes is used for the correlation treatment. The results are analyzed and compared with the experimental data and corresponding all‐electron results. © 2013 Wiley Periodicals, Inc.     

Analysis of nitromethane thermal decomposition at low temperatures

The thermal decomposition of nitromethane (NM) over the temperature range from 580 to 700 K at pressures of 4 Torr to 40 atm was analyzed. On the basis of literature data, with the use of theoretical transitional curves of the modified Kassel integral, the rate constants k of NM decomposition at the upper pressure limit were determined. The values thus obtained are in good agreement with the results of extrapolation of the high-temperature (1000–1400 K) k _{1, ∞} values to lower temperatures. The reasons for which the NM decomposition rate constants differ by two orders of magnitude at low temperatures are considered. A general expression for the NM decomposition rate constant at the upper pressure limit over the 580–1400 K temperature range was determined: k _{1, ∞} = (1.8 ± 0.7) × 10¹⁶ exp((?58.5 ± 2)/R _T ) s^?1. These data disprove the hypothesis that a nitro-nitrite rearrangement takes place during the NM decomposition at low temperatures.     

Cyclometallation of the Dimethylamide Ligand in the Reaction of Ta(NMe2)5 with CS2

Russian Journal of Coordination Chemistry - The reaction of Ta(NMe2)5 with CS2 resulted in the isolation of azametallacyclopropane complex [Ta(MeDtc)3(η2-CH2NMe)] (I, MeDtc =...     

On the Possibility of Studying the Fraction of Inhomogeneities in Optical Nonlinear Media Using Time-Resolved Inline Digital Holography

Technical Physics - An approach to determining the fraction of inhomogeneities of the optical nonlinear properties of a transparent medium characterized by a spatial variation of nonlinear...