High temperature quenching cross sections for nitric oxide laser-induced fluorescence measurements

Abstract

Collisional quenching cross sections for laser-induced fluorescence from NO A(v′=0) are measured for H2O, CO2, O2, NO, N2, H2, Ar, C2H6, and CO as a function of temperature from 300 to 1750 K. Room temperature cross sections vary widely (≤0.03 Å2 for N2, H2, C2H6, and Ar to ≥100 Å2 for H2O). As temperature increases, cross sections for H2O and CO2 decrease, cross sections for O2 and NO remain constant, and cross sections for N2, H2, CO, and C2H6 increase. These data provide quantitative quenching corrections for laser-induced fluorescence measurements of NO concentrations in nonreacting and reacting flows. Physical quenching models (based upon NO–Q and NO+–Q− collision complexes) are reviewed and used for experimental data correlation and extrapolation. A new quenching mechanism is proposed for weak quenchers.