Trace Methane Absorption Measurements Using a DF Laser Intracavity Spectrophone

Abstract

The deuterium-flouride (DF) laser emits in the 3.5 to 4.0 μm atmospheric transmission window. Atmospheric absorbers in the window include isotopic water (HDO), N2O, CH4, and small contributions from both line and continuum H2O absorption. The purpose of our study was to measure trace methane absorption at DF laser frequencies, to compare our results with our predictions using the AFGL line parameters compilation, and to develop sensitive spectrophone measurement techniques.