EMPI - Reactive Fluids

Atomic resonance absorption spectroscopy (ARAS) and ring dye laser spectroscopy (RDLAS) are very selective and sensitive detection methods for the time-resolved detection of atomic (ARAS) and molecular (RDLAS) species, e.g., in shock-tube experiments.

ARAS

Both microwave discharge lamps (in the VUV range, for H, O, N, C, I, Cl, S) and hollow-cathode lamps (in the UV range, for semi-metals and metals such as Si, Fe, Ga, Sn, ...) are used as light sources. After passing through the shock wave tube, the light is spectrally separated in a monochromator and detected with photomultipliers. The quantitative evaluation is then carried out with the help of previously created calibration curves. The detection limit is below 0.1 ppm.  

RDLAS

A ring dye laser (see figure below) is used as the light source, the output of which is often doubled. The method is mainly used for OH detection, but can also be used for species such as SiH₂ , C₂ , NH₂ , CH₃ or TiN. Quantification is carried out using the calculated temperature- and pressure-dependent absorption coefficients. The detection limit is below 1 ppm.