Infrared line intensity measurements in the v = 0-1 band of the ClO radical

Line intensities of the ClO radical in the fundamental vibrational band, v = 0-1, have been measured using a high-resolution Fourier transform spectrometer coupled to a long path length absorption cell. The ClO infrared absorption spectra were recorded at 0.004 cm^-1 unapodized resolution in 50 coadded scans at total pressures less than or equal to 0.4 torr, He buffer gas. Spectra were recorded at calibrated [ClO] over the range 4 × 10¹² to 1.4 × 10¹³ molecule cm^-3, using two different chemical sources of ClO: Cl + O₃ and NO + OClO. The band intensity was measured as S = 9.68 ± 1.45 cm^-2 atm^-1 (95% confidence level) at 296 K, which is in agreement with a recent ClO band intensity determination using the concentration independent Herman-Wallis method of band intensity analysis (Burkholder et al, 1987a). This value of the ClO band intensity is a factor of 2 greater than the value recently reported by Kostiuk et al. (1986). A N₂ collisional broadening coefficient of γ⁰ = 0.093 ± 0.018 cm^-1 atm^-1 (95% confidence level) was determined from spectra recorded with 10 torr N₂ added. A source of systematic error in the use of the Cl + O₃ reaction as a quantitative source of ClO radicals is discussed.