Parallel Session: Infrared, Contributed Talk (15min)

Oxygen B-band P-branch study: simultaneous observation of Dicke narrowing and speed-dependence effects

A. A. Balashov1,2, K. Bielska1, J. Domysławska1, S. Wójtewicz1, M. Słowiński1, M. Piwiński1, A. Cygan1, R. Ciuryło1, D. Lisak1
1Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziadzka 5, 87-100 Torun, Poland, 2Institute of Applied Physics of the Russian Academy of Sciences, Ulyanov str. 46, 603950 Nizhny Novgorod, Russia

Oxygen is one of the two most abundant molecular gases in the terrestrial atmosphere. B band is the second most intense band in the red part of the absorption spectrum of the O2 molecule. It is less commonly used for the remote sensing of the atmosphere mainly because the B-band intensity is about 15 times lower than the A-band. Until recently another limiting factor was the lack of accurate laboratory data. Accurate reference data, including full sets of line-shape parameters, is necessary for multiple atmospheric applications, in particular, accurate determination of the pressure and temperature profiles [1] across the atmosphere and improved parameters of clouds such as their top height [2].

In this study, we measured line-shape parameters of three transitions from the P branch. In contrast to the previous study [3], we simultaneously observe the speed-dependence of the collisional broadening and the Dicke narrowing effect [4], as well as the line asymmetry due to the speed-dependence of the collisional shifting for the pressures down to 1.1 kPa. It became possible due to the significantly increased spectra signal-to-noise ratio. The measurements were done with two experimental techniques: well-established cavity ring-down spectroscopy (CRDS) [5] and cavity mode-width spectroscopy (CMWS) [6,7] that allowed us a more reliable estimation of the determined line-shape parameters systematic uncertainties. The unperturbed line positions are determined within 40 kHz and the line intensities at 0.2% level. New results are compared with our previously published data [3] of the P-branch measurements and observed systematic deviations on the line intensities are explained.

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[2] A. Kuze, K. V. Chance, Journal of Geophysical Research, 1994, 99 (D7),  14481.

[3] S. Wójtewicz, A. Cygan, P. Masłowski, J. Domysławska, D. Lisak, R. Trawiński, R. Ciuryło, Journal of Quantitative Spectroscopy and Radiative Transfer2014, 144, 36–48.

[4] S. Pine, Journal of Quantitative Spectroscopy and Radiative Transfer, 1999, 62 (4), 397–423.

[5] A. O’Keefe, D. A. G. Deacon, Review of Scientific Instruments, 1988, 59 (12), 2544–2551.

[6] A. Cygan, D. Lisak, P. Morzyński, M. Bober, M. Zawada, E. Pazderski, R. Ciuryło, Optics Express, 2013, 21 (24), 29744

[7]D. A. Long, G. W. Truong, R. D. Van Zee, D. F. Plusquellic, J. T. Hodges, Applied Physics B: Lasers and Optics, 2014, 114 (4), 489–495.