Measurement of absorption spectra for atmospheric methane by a lidar system with tunable emission wavelength in the range 1.41–4.24 μm

Abstract

We have developed, built, and tested an automated differential lidar system for measuring low concentrations of atmospheric gases, based on an optical parametric oscillator tunable in the near IR region. We have calculated the spectral shift of the relative intensities of the individual lines in the ν 3 absorption band of methane. In comparing the measured and calculated spectra, we did not observe any shifts in the ν 3 absorption band of methane. At the same time, in the experimental spectra we observe broadening of the Q branch and the individual lines of the P branch.