Coulomb correlations and electron-hole liquid in double quantum wells

It has been shown that many-body Coulomb correlations in double quantum wells with spatially separated electrons and holes result in the formation of a degenerate electron-hole liquid where an average distance between the particles is smaller than the size of an isolated exciton. This state turns out to be energetically more favorable than the exciton gas. The results have been obtained under the assumption that there are many different sorts of electrons and holes in the system, which is the case, in particular, in multivalley semiconductors. The relation to the experiments on the observation of luminescent regions in such systems is discussed.     

A new structural type of liquid crystal Crystal structures and thermotropic mesophases of dihydroxytetraalkyldisiloxanes: Columnar phases with hydrogen bonded assemblies

Abstract

Previous structural investigations of mesogenic organosilicon compounds (1, 3-dihydroxytetraalkyldisiloxanes, [R₂(OH)Si]₂O, R = C _n H_2n+1) which form thermotropic phases are outlined. The crystal and molecular structure determination of a non-mesogenic member of this series [Me₂(OH)Si]₂O is described. It is inferred that the mesophases formed by this family of compounds belong to a new structural type with columnar stacks of the molecules laced together with hydrogen bonds.     

Synthesis of a liquid crystal paramagnetic copper complex with Aminovinylketone and the structural study of its single crystal and mesophase

We have synthesized a mesogenic copper complex with aminovinylketone. The X-ray structural analysis has shown that the molecules of the complex in a single crystal (a=9.107, b=11.446, c=11.496 , =81.06, =73.20, =80.72°, and Z=1) form sheets with thickness determined by the cross molecular sizes. When the substance is heated, phase transitions are observed: Cr196Cr X128 S₁187 S_A189 N192°C i. We have carried out EPR studies of various phase states of the complex. It is shown that in the mesophase, the diamagnetic component of magnetic anisotropy is larger than the paramagnetic component resulting in the orientation of the long molecular axes along the outer magnetic field.Kazan Physicotechnical Institute. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 6, pp. 49–55, November–December, 1993.Translated by T. Yudanova     

Synthesis of 3-(Benzotriazol-1-yl)naphthoquinone Derivatives

2,3-Bis(benzotriazol-1-yl)-1,4-naphthoquinone reacts with aliphatic and aromatic amines to give the corresponding 2-amino-3-(benzotriazol-1yl)-1,4-naphthoquinones, and its reaction with alkali gives 2-hydroxy-3-(benzotriazol-1-yl)-1,4-naphthoquinone.     

Low-supersaturation nucleation kinetics in beryllium electrocrystallization

Classical electrocrystallization theory has been used to estimate the beryllium nucleation rate in electroplating on tungsten from molten chloride in the galvanostatic mode. Details of the process have been identified, and satisfactory agreement is obtained between the observed and calculated values.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, No. 2, pp. 245–249, March–April, 1987.