Near-infrared absorption spectroscopy of oxygen and nitrogen gas mixtures

Near-infrared absorption cross-sections of oxygen and nitrogen gas mixtures have been determined from laboratory measurements using Fourier transform spectroscopy and a long path-length absorption cell. Spectra were recorded at instrument resolutions of 0.5 and 0.05 cm(-1), between 2200 and 12500 cm(-1) (4.5-0.8 mu m) Cross-sections were determined for mixtures of 21%, 50%, and 75% oxygen in nitrogen, at a total pressure of 100 kPa and temperatures of 200, 230, and 294 K. The absorption 'continua' centred at 1.06 and 1.27 mu m could each be fitted with two overlapping Voigt profiles: one linearly dependent on oxygen partial pressure, and the other varying quadratically with oxygen partial pressure. (C) 1999 Elsevier Science B.V. All rights reserved.