Pressure broadening, lineshapes, and intensity measurements in the 2 ← 0 band of NO

Abstract

Lineshape and intensity measurements were made on the overtone band ( v = 2 ← 0) of nitric oxide (NO) using a tunable difference-frequency laser system. Self- and N 2-pressure broadening coefficients were obtained at 296 K, and a small amount of collisional, or Dicke, narrowing (which reduces the Doppler width by ∼9% at 50 Torr) was also evident. The pressure broadening observed for the 2 Π 3 2 transitions was larger than that of the 2 Π 1 2 for corresponding J by about 7%, so an empirical scaling law model was fit to the broadening coefficients to determine the role of interstate (spin-flipping) collisions. A small collision-induced asymmetry in the Λ-doublet transitions of the 2 Π 1 2 level was also observed. The measured line intensities yield an integrated band intensity of 1.878( −40 +90) cm −2 atm −1 at 296 K and a Herman-Wallis F factor which determines the relative signs of terms in the dipole moment expansion.