Absorption of CO laser radiation by NO

Abstract

Absorption of CO i.r. laser radiation by NO has been studied over the temperature range 300°–4000°K using a grating-tunable CO laser in conjunction with a room-temperature absorption cell and a shock tube. The CO laser line with strongest absorption at elevated temperatures was determined to be the V = 7 → 6, J = 12 → 13 line at 1935.4817 cm -1, which is nearly coincident with the 2Π 3 2 V = 0 → 1, J = 37/2 → 39/2 transition in NO. The absorption cell measurements (300°K) were used to infer the position of the NO absorption line (a Λ-doublet at 1935.492 and 1935.497 cm -1) as well as collision-broadening parameters in pure NO and NO dilute in foreign gases: 2γ° (collision-broadened full width at half maximum in cm -1 atm -1 at 300°K) = 0.110, NO-NO; 0.072, NO in Ar; 0.069, NO in Kr; 0.109, NO in N 2. Calculations of the NO absorption coefficient at 1935.4817 cm -1 are presented for a range of conditions applicable to current studies in combustion and NO x kinetics. Shock tube measurements (630°–4000°K) supporting these calculations are also reported.