Line Mixing Study On The Nitric Oxide Fundamental Band Near 5.3 Microns

\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.52]{Hartmann_XiMult2_1m2xi_result_forISMS.eps} \end{wrapfigure} We present absorbance measurements of the full fundamental ro-vibrational band of nitric oxide in nitrogen bath (NO/N$_2$) from 1700 to 2000 cm$^{-1}$ at pressure and temperature conditions of 20-34 atm and 293-802 K, respectively. These measurements were taken with a narrow-linewidth, broad-scan EC-QCL laser aligned through a high-pressure, high-temperature static cell. The results were compared to a line mixing model utilizing relaxation matrix formalism and the modified exponential gap (MEG) fitting law that was previously developed using absorbance measurements limited to the R-branch\footnote{Almodovar, C.A., ``Infrared Laser Absorption Spectroscopy of Nitric Oxide for Sensing in High-Enthalpy Air,'' Ph.D. diss., (Stanford University, 2019)}. Improved knowledge from full-band absorbance measurements, including the P and Q-branches, indicates the need to account for inter-branch line mixing effects which were omitted in the previous model. A modified MEG line mixing model is presented with additional inter-branch coupling transfer rates and their associated scaling factors, showing stronger agreement with the measured spectra