Empirical line parameters of methane in the 1.63-1.48 μm transparency window by high sensitivity Cavity Ring Down Spectroscopy

The empirical parameters of the absorption lines of methane in the 1.58 μm transparency window have been retrieved from spectra recorded by high sensitivity Cavity Ring Down Spectroscopy at room temperature. The achieved sensitivity (αmin ∼ 3 × 10−10 cm−1) represents a gain of three orders of magnitude compared to previous studies. The CH3D absorption has been found to represent a significant fraction of the total methane absorption in the region.