High pressure solid state amorphization of Si,Ge and solid solutions Si:GaAs,Ge:GaSb

Abstract

The bulk amorphous tetrahedral semiconductors (Si, Ge. Si_0.89(GaAs)_0.11, Ge_1?x(GaSb)_x (0.12<X<I)) were obtained using solid state amorphization. The disordering process occurs at the decompression of high pressure phases Si II, Gell at low temperatures and of solid solutions Sill: GaAs, GeII: GaSb at room temperature. The structure and stability of the obtained phases were investigated     

Nonmetal-metal transitions in liquid substances under high pressure

Abstract

In the melts of Te, Se, S, I₂ and Mg₃Bi₂ the nonmetal-metal transitions were found under pressure. The transitions are accompanied by a decrease of the volume. The transitions seem to terminate at high temperature by “critical regions”. For S and Se the kinetics of the transitions and the pressure influence on the solidification of the melts were investigated.

The existence of the transitions of this kind gives an explanation of anomalies of melting curves of some substances.     

Chemiluminescence upon isomerization of dimethyldioxirane in the gas phase and on a sorbent surface

Chemiluminescence (CL) was found upon the isomerization of dimethyldioxirane in the gas phase under argon atmosphere. The intensity of CL increases as temperature increases and decreases with time at constant temperature. If Silipor is placed in a cell containing the dimethyldioxirane vapor in argon, the intensity of CL sharply increases (more than 10 times) and then decreases following the exponential law. In all cases tripletly excited methyl acetate is the emitter of chemiluminescence.[/ p]Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2582–2583, October 1996.     

Multiplicity studies and effective energy in ALICE at the LHC

In this work we explore the possibility to perform “effective energy” studies in very high energy collisions at the CERN large hadron collider (LHC). In particular, we focus on the possibility to measure in pp collisions the average charged multiplicity as a function of the effective energy with the ALICE experiment, using its capability to measure the energy of the leading baryons with the zero degree calorimeters. Analyses of this kind have been done at lower centre-of-mass energies and have shown that, once the appropriate kinematic variables are chosen, particle production is characterized by universal properties: no matter the nature of the interacting particles, the final states have identical features. Assuming that this universality picture can be extended to ion–ion collisions, as suggested by recent results from RHIC experiments, a novel approach based on the scaling hypothesis for limiting fragmentation has been used to derive the expected charged event multiplicity in AA interactions at LHC. This leads to scenarios where the multiplicity is significantly lower compared to most of the predictions from the models currently used to describe high energy AA collisions. A mean charged multiplicity of about 1000–2000 per rapidity unit (at η∼0) is expected for the most central Pb–Pb collisions at . In memory of A. Smirnitskiy     

Crystal and molecular structures of pinacol ester of ferrocenyl-1,1′-diboronic acid

The molecular and crystal structure of pinacol ester of ferrocenyl-1,1′-diboronic acid was determined by X-ray crystallography. Dedicated to the 90th anniversary of the L. Ya. Karpov Institute of Physical Chemistry. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1289–1291, June, 2008.     

Automated measurement of birefringence: Development and experimental evaluation of the techniques

Traditional photoelasticity has started to lose its appeal since it requires a well-trained specialist to acquire and interpret results. A spectral-contents-analysis approach may help to revive this old, but still useful technique. Light intensity of the beam passed through the stressed specimen contains all the information necessary to automatically extract the value of retardation. This is done by using a photodiode array to investigate the spectral contents of the light beam. Three different techniques to extract the value of retardation from the spectral contents of the light are discussed and evaluated. An experimental system was built which demonstrates the ability to evaluate retardation values in real time.