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

Frequency-stabilized cavity ring-down spectroscopy measurements were performed in the P-branch of the O2 A-band [b1g
+←X 3g −(0,0)] near atmospheric pressure. Line mixing parameters and
collision-induced absorption were quantified and reported. These measurements show qualitative differences with those taken at relatively high pressure (2 MPa–20 MPa). We also assess the implications of these measurements on atmospheric retrievals.