Photocatalysis of reactions involving reduction of nitrogen-containing compounds by ethanol in an organized 18-tungsten diphosphate-cadmium sulfide system

Cadmium sulfide and heteropolytungstate were found to form an organized photocatalytic system providing separation of photogenerated charges. Reduction of nitrobenzene, nitrosobenzene, and phenylhydroxylamine to aniline has been investigated in this system; kinetic patterns have been established and quantum yields of the reactions have been determined.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 30, No. 4, pp. 206–210, July–August, 1994.The authors are grateful to the Fund for Fundamental Research of the Ukrainian State Committee on Science and Technology for supporting this work.     

Sensitization of cadmium sulfide by cyanine dyes in the photocatalytic production of hydrogen

The possibility of photocatalysis of hydrogen production from aqueous alcohol mixtures by heterostructures of cadmium sulfide with dyes under the action of light with >600 nm was shown. A probable mechanism of the sensitization is proposed on the basis of an examination of the spectral, photochemical, and electrochemical data obtained.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 31, No. 6, pp. 370–374, November–December, 1995.The authors are grateful to S. V. Shinkorenko for providing the dyes that they synthesized for the first time.     

Electronic and ESR spectroscopic study of thiocyanate-containing coordination compounds of titanium(III) in alcohol solutions

In an investigation of electronic and ESR spectra, it has been established that titanium(III) with the thiocyanate ion (in ethanol) forms distorted tetrahedral and octahedral complexes. The tetrahedral compounds, which are hydroxo complexes of titanium(III) that contain one hydroxyl group and three thiocyanate ions in the coordination sphere, give signals in the ESR spectra with g_o=1.960, A_o=15.0·10^–4 cm^–1 g=1.958, A ^Ti =26.4·10^–4cm^–1, g= 1.691, A^Ti=9.0·10^–4 cm^–1. In the ESR spectra of liquid solutions, additional splitting on the nitrogen atoms is manifested(A _o ^N =2.2·10^–4 cm^–1), which indicates bonding of thiocyanate ions through the nitrogen atom. The pseudo-octahedral complexes of titanium(III), containing from two to six thiocyanate ions in the coordination sphere, are characterized by d-d absorption bands in the 520–590 nm region; and at 77°K, they give anisotropic ESR signals. On the basis of the temperature dependences of the equilibrium constants for the reaction of conversion of the tetrahedral complexes to the octahedral complexes, and also the lifetimes of the tetrahedral complexes, values have been estimated for the heat of reaction (H=26.8 kJ/mole) and the entropy change (S=–1.66 kJ/mole·°K) of the equilibrium process, and also the activation energy for the reaction of titanium(III) thiocyanate formation (E=37 kJ/mole).Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 5, pp. 560–567, September–October, 1985.     

Application of the Pulsed-Neutron Method for Measuring the Reactivity of the Fissile Systems with Reflector

The experiments on recording the radiation decay signal of the GIR2 reactor core in the range from 0 to 40 µs when exposed to an external intense neutron pulse with a duration of ∼1 µs are performed. The reactivity interval from subcritical (−7.5 β) to critical (+0.28 β) states of the reactor is studied. It is found that the signal of the detector with a plastic scintillator depends on the reactivity and is proportional to the change in the density of thermalized neutrons in the reactor converter. The results show that the reactivity of the GIR2 reactor can be determined on the basis of measurement of the signal decay of a scintillation detector and the well-known expression $${\alpha _\infty } = {\beta \over \Lambda }(\rho - 1)$$ to calculate the reactivity values only for states with a reactivity greater than ∼−3 β.     

Tungsten-assisted modification of graphite furnaces for an atomic absorption spectrometer

We have used scanning electron microscopy to study changes in the morphology of the inner surface of graphite tube furnaces for an atomic absorption spectrometer when modified by tungsten. We have demonstrated the role of the tungsten-containing material as a dividing interlayer between the sample to be dispensed and the carbon component of the furnace. We consider the advantages and disadvantages of furnaces modified by the proposed methods.     

Quantum Key Distribution with Untrusted Detectors Accessible to an Eavesdropper

JETP Letters - A simple fundamental modification of quantum key distribution protocols has been proposed: it is not required to protect the results of avalanche detectors from an eavesdropper, but...     

Diastereoselective cycloaddition of (S)-N-(1-phenylethylimino)trifluoropropionate and trifluoroethylphosphonate with diazomethane

The cycloaddition reaction of (S)-(α-phenylethylimino)trifluoropropionate with diazomethane leads to a diastereomeric mixture (4.5:1) of 5-trifluoromethyl-1,2,3-triazoline-5-carboxylates. Enantiopure diastereomers were isolated by column chromatography and converted into their respective non-racemic 2-trifluoromethyl-aziridine-2-carboxylates and carboxylic acids. The absolute configuration of newly formed stereogenic centers was determined by XRD analysis. The stereoselective reaction between (S)-N-(α-phenylethyl)trifluoroacetimidoylphosphonate and diazomethane produces a diastereomeric mixture (2.5:1) of 5-trifluoromethyltriazoline-5-phosphonates readily separated by column chromatography in diastereomerically pure forms.