From optical spectra to phase diagrams - the binary mixture N2-CO

Анотація

We investigated the T-c% phase diagram of the binary system N₂-CO. From changes in IR spectra of all kinds of mode excitations (phonons, vibrons) we were able to determine the temperature of phase transitions (solid-solid, solid-liquid). The improvements in comparison to structural investigations by x-rays or electrons are the following: sample growing and handling with perfect optical and thermodynamic quality; determination of actual concentration (N₂)_x(CO)_y from optical spectra; reduction of thermal hysteresis by careful cooling-heating cycles of the samples.