Empirical line parameters of methane from 1.1 to 2.1 μm

Abstract

To provide line parameters for the near-infrared methane spectrum, 35,306 line positions and intensities at room temperature were retrieved between 6180 and 9200 cm −1, along with 4936 lines between 4800 and 5500 cm −1. For this, laboratory absorption spectra were recorded at 0.010–0.022 cm −1 resolution using the McMath-Pierce Fourier Transform Spectrometer located on Kitt Peak in Arizona. Positions were calibrated using CO transitions at 2.3 and 1.6 μm and H 2O lines at 1.9 and 1.3 μm. The minimum line intensity included was 3.7×10 −26 cm −1/(molecule cm −2), and the combined sum of the intensities in these two intervals was 7.085×10 −20 cm −1/(molecule cm −2) at 296 (±4) K. Quantum assignments from the literature were matched for 1% of the features, and a new methane database was compiled for the near-infrared.