Thermal Analysis provides ideal tools für the characterization of organic and inorganic, either solids or liquids. Thermodynamic transitions, thermal stability, decomposition and chemical reactions can be detected and quantified with high accuracy over a broad temperature range
The identification of gases released directly from the sample or during thermal treatment cannot be performed just by thermal analysis, but coupling a spectroscopic method such as Fourier-Transform-Infrared (FT-IR) spectroscopy is an excellent solution.
IR spectroscopy is a classical technique, which depends upon the interaction of infrared radiation with the vibrating dipole moments of molecules. It gives, with the exception of homonuclear diatomics and noble gases, a characteristic spectrum for each substance.
This combination yields a powerful analytical technique that combines the quantitative capabilities of TG and the identification capabilities of FT-IR spectroscopy.
Three modes of connecting FT-IR to TG:
Coupling to an external gascell via transfer line for highest FT-IR system flexibility.
Coupling to an internal gascell via transfer line using the FT-IR sample chamber.
Direct PERSEUS® coupling without transfer line.
The external module is equipped with additional detector - either room temperature operated DLaTGS type, or high sensitive liquid nitrogen cooled MCT´s. Simple computer controlled switch allow the setup of either sample compartment measurements or run combined TG-FT-IR analysis.
The detection sensitivity of compounds follow beer´s law. Depending on the path length of the cell, the concentration and the absorptivity of the investigated molecule. The absorbtivity as natural constant can not be invluenced by the experimental setup. The longer the pathlength, the more Molecules are passing through at any given moment. On the other hand the gas concentration is also influenced by the volume of the cell - and on the other side by the amount of sample needed. The lower the volume, the higher the concentration of the gases evolved.
PERSEUS® is the name given to the patended Alliance of the tiny and efficient ALPHA II FT-IR spectrometer and the NETZSCH Thermoanalyzers.
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