Spectroscopy of methane using a Nd:YAG laser at 134 μm

Abstract
We present measurements of the absorption coefficient of methane in the ν2 + 2ν3 band obtained with a neodymium:yttrium aluminum garnet (Nd:YAG) laser tuned by the use of an intracavity étalon to 7472 cm−1 (1.3383 μm). The linewidth of the laser was shown to be comparable to that of the pressure-broadened methane feature while the absorption coefficient of methane at 1-atm pressure was measured to be 0.59 m−1 atm−1. These basic findings indicate that a practical methane detection system using laser radar (lidar) based on a Nd:YAG laser may be possible.
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