Pressure broadening in the oxygen b1Σ+g(v′=1)←X3Σ−g(v″=0) band measured by cavity ring-down spectroscopy

We have measured coefficients for pressure broadening of the oxygen b1Σ+g(v′=1)←X3Σ−g(v″=0) band at 688 nm by N2 using cavity ring-down spectroscopy. There is a noticeable dependence on rotational quantum number, consistent with significant anisotropy in the N2–O2 intermolecular potential. The results also suggest that pressure broadening coefficients may depend on the collider and on the vibrational quantum number of the absorber.