Abstract

Chemical sensing using mid infrared laser absorption spectroscopy (MIR-LAS) in the molecular fingerprint region from 3 to 20 µm, which contains strong ro-vibrational absorption features of a large variety of gaseous species, has been established as a powerful in-situ diagnostic tool for molecular plasmas and for trace gas detection. Quantum cascade lasers (QCL) in particular have become the infrared light sources of choice in the mid infrared. MIR-LAS provide a means of detecting stable and transient molecular species in ground and excited states and of measuring the concentrations and temperatures of reactive species in plasmas and gases. Special attention is devoted to in-situ studies of plasma chemistry and reaction kinetics in gas discharges and on highly sensitive trace gas detection using optical cavities. A link is thereby provided to modelling of plasmas and surface phenomena.

© 2016 Optical Society of America