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

Abstract

This paper reports on the effect of collisions between nitrogen and oxygen on absorption in the A-band near 760 nm under atmospheric conditions relevant for satellite retrieval studies. We use pulsed laser cavity ring-down spectroscopy with a narrow bandwidth laser and use pressure scans to increase the accuracy of the measured oxygen extinction coefficients. We use the so-called Adjustable Branch Coupling model to describe line mixing in the magnetic allowed A-band dipole absorption and we retrieve the collision induced absorption spectrum due to N₂–O₂ collisions.

Keywords:

• oxygen
• A-band
• collision induced absorption
• cavity ring-down spectroscopy
• line mixing

Acknowledgements

We thank Prof. Dr. Tonkov of the Saint Petersburg University for his inspiration. We thank Dr. Tran and Dr. Hartmann for providing us with numerical data of their CIA spectra of pure O₂. We acknowledge the financial support from NWO (Echo project).

Notes

Note

1. The dimensionless unit amagat (amg) is defined as the ratio of the measured density to the density of the standard atmosphere.