Optoelectrical method for the measurement of pressure and for the investigation of the phase equilibrium of deeply colored or turbid mixtures under high pressures.
An optoelectrical method for the measurement of pressure and for the investigation of the phase behavior of deeply colored or turbid systems under high pressures is described where the light source and the light detector are in direct contact with the substance to be measured. As a light source, special infrared and visual light emitting diodes (LED) and as a detector appropriate photoelements are used. The behavior of the light emitting diodes and of the photoelements under high pressure is discussed. As a test for this method the solid-liquid transition of pure cyclohexane, the fluid-fluid separation in the binary system nitromethane+ethylene, and the phase behavior of the liquid crystal 4,4'-diheptoxy-azoxybenzene were investigated at pressures up to 1 kilobar; additionally the solid-liquid phase transition of the binary system dimethylsulfoxide+iodine was studied.
Alwani
Z
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Department of Chemistry, University of Bochum, 4630 Bochum-Querenburg, West Germany.