Experimental intensity and lineshape parameters of the oxygen A-band using frequency-stabilized cavity ring-down spectroscopy

Abstract

Line intensities, self- and air-broadened linewidths, pressure-induced shifts, and collisional narrowing coefficients were measured from 2 ⩽ J′ ⩽ 32 in the P branch of the O 2 A-band (12 975–13110 cm −1) utilizing Galatry line profiles. Spectra were recorded using the frequency-stabilized cavity ring-down spectrometer located at NIST, Gaithersburg, MD with a spectral resolution <0.0001 cm −1 and noise-equivalent absorption coefficient of 6 × 10 −8 m −1 Hz −1/2. Line intensities, obtained from calibrated gas samples for 2 ⩽ J′ ⩽ 32, are ∼1% lower than the values in current spectroscopic databases. At higher J (18 ⩽ J′ ⩽ 32), the measured air- and self- broadened half widths are up to 20% lower than the extrapolated values given in HITRAN 2004, while corresponding half-widths for 2 ⩽ J′ ⩽ 15 are in better agreement. Available self-broadened half widths are fitted to empirical expressions with an rms of 0.8%. We discuss the implications of our results for accurate remote sensing of surface pressure and photon path length distributions.