Tunable diode laser measurements of the band strength and collision halfwidths of nitric oxide

Abstract

The strength of the fundamental absorption band of nitric oxide at 5.3 μm and collision halfwidths of nitric oxide lines broadened by nitrogen, argon, and combustion gases were measured in absorption cell, flat flame and shock tube experiments using a tunable diode laser. Room temperature absorption measurements were made in an absorption cell filled with NO/N 2 or NO/Ar mixtures or with probe-extracted combustion gases. High temperature (to 2500 K) absorption measurements were performed for NO in N 2 and NO in Ar using a shock tube, and for NO in combustion gases using a flat flame burner. Absorption measurements were made on lines from 1860–1925 cm −1, ( Ω= 1 2 and 3 2 , P( 5 2 - R ( 29 2 )) resulting in a band strength of 123±8 cm -2 atm −1 at 273.2 K. Collision halfwidth dependencies for each broadening species were examined as a function of rotational quantum number and temperature.