Parameters of CH4 Absorption Lines Broadened by Atmospheric Air Pressure in the 2300 nm Region

Abstract

Methane is one of key greenhouse gases, whose concentration has been increasing in recent decades, thus increasing the Earth’s surface temperature. To monitor the methane content in the atmosphere the accurate knowledge of the absorption spectrum of CH₄ molecule is required. In this work, the parameters of methane absorption lines broadened by atmospheric air pressure are presented in the spectral region 4345–4360 cm⁻¹. Data were derived from spectra recorded at a Bruker IFS 125HR Fourier spectrometer with a spectral resolution of 0.005–0.01 cm⁻¹ at room temperature and five values of buffer gas pressure. Atmospheric transmission was simulated using the derived results and line parameters from HITRAN and GEISA spectroscopic databases. The comparison with measured atmospheric solar spectra shows the CH₄ absorption line parameters found in this work to coincide the best in terms of root-mean-square deviation.