The effect of collisions with nitrogen on absorption by oxygen in the A-band using cavity ring-down spectroscopy.

Frequency-stabilized cavity ring-down spectroscopy measurements of line mixing and collision-induced absorption in the O2 A-band

“…While the present CIA spectra exhibit similar integrated intensities to those measured in previous, lower resolution experiments, 14,[27][28][29] we observe qualitative differences in the observed spectral shape (see Figure 5). Namely, both of our observed O 2 -O 2 and O 2 -air CIA spectra are noticeably nar- 14,[27][28][29] The present spectrum is the result of a weighted average of the measurements made at two different pressures.…”

“…Namely, both of our observed O 2 -O 2 and O 2 -air CIA spectra are noticeably nar- 14,[27][28][29] The present spectrum is the result of a weighted average of the measurements made at two different pressures. The shown uncertainties for our measurements are based on a standard uncertainty of 0.7 × 10 −6 in the empty-cavity losses (as estimated from a series of empty cavity measurements made over the course of several months).…”

“…Regardless of the model utilized, the measured CIA spectrum exhibited far less absorption in the far wing region (12 975 cm −1 -13 010 cm −1 ) than that which was found in earlier studies. 14,[27][28][29] …”

Multispectrum analysis of the oxygen A-band

“…Comparison with Long et al 2012 [23] (red) and Spiering et al 2011 [58] (blue) and present study (green) collision induced absorption coefficients for air ( ϱ O 2 = 0.21, ( ϱ N 2 = 0.79). One amagat (am) is the density of gas at 101325 Pa and 273.15 K.…”

“…8 are the absorption coefficients from (red) [30], (blue) [58], and the (black) values from Tran [22] that are included in HITRAN2012. Our derived values (green) in the A-band P-branch at 13100 cm −1 are in 20% lower compared to Long et al [23] and the CIA of Spiering et al [58] is 50% of our value at the same wavenumber, however the three data sets converge somewhat at lower wavenumbers and only agree with Tran et al near 13075 cm −1 . Unlike Tran et al the new CIA in the R-branch rapidly drops near the band-head, but does not go to zero.…”