Spectrally-resolved ultraviolet absorption measurements of shock-heated NO from 2000 K to 6000 K for the development of a two-color rotational temperature diagnostic

In high-enthalpy air flows, nitric oxide (NO) formation and removal involves multiple, complex energy transfer processes that occur under nonequilibrium conditions, thus motivating the need for diagnostic methods to probe such flows in laboratory settings. this work, a rotational temperature NO was developed using spectroscopic model (Stanford model) of γ-bands inform optimal wavelength candidates absorption two continuous-wave (CW), ultraviolet (UV) lasers. Absorption cross-sections shock-heated were measured with CW UV lasers over range temperatures wavelengths, results compared Stanford model. All measurements completed behind reflected shocks 0.4% 2% mixtures argon (Ar). Fixed-wavelength cross-section from 2000 K 6000 between 1 atm 0.085 made at nominal wavelengths 226.1026 nm 224.8155 nm. Additionally, fixed-temperature 226.1013 226.1035 0.8 atm. The combination experiments provided sweep compare against formulation collisional broadening parameter, 2γ, divided into regimes, transitioning 2500 K. line positions R11(26.5), R12(34.5), Q21(26.5), Q22(34.5) transitions around Q11(12.5), R12(19.5), P21(12.5), Q22(19.5) adjusted best fit data. A vibrational equilibrium assumption used determine translational point determination, while coupled vibration-dissociation (CVDV) characterized extent dissociation determination. Data both temperature-sweep wavelength-sweep agree within ± 10% model, most falling 5% predictions. Oxygen (O2) also taken dilute O2 Ar quantify interfering absorbance chosen wavelengths.