High-Resolution Dual-Comb Spectroscopy in the 9.5 μm Region to Study Ammonia Formation in N2-H2 Plasmas

To improve plasma-assisted processes, optical spectroscopy provides in situ measurements of plasma parameters including chemical composition, number density and temperature, amongst others. Traditionally, tunable continuous-wave (CW) laser absorption spectroscopy is used for in situ detection and quantification of stable and transient species in plasmas (e.g., [1]). However, the narrow spectral coverage of many CW lasers reduces the number of transitions that can be interrogated at one time, and therefore limits the available information regarding the number of species present, their mole fractions and temperatures.