High-resolution spectra of atmospheric water vapor in the near-IR using Raman-shifted alexandrite laser

Abstract

We have developed a pulsed, narrow line Raman shifted alexandrite laser to produce tunable near-IR radiation in the 1140 nm absorption band of water vapor. With the first Stokes Raman conversion in hydrogen, the full tuning range of alexandrite, 730-790 nm, can potentially cover the wavelength range 1050 1200 nm. The application to differential absorption lidar, DIAL, is the vertical profiling of humidity and temperature in the atmosphere. This paper reports the application of Raman-shifted alexandrite radiation for new quantitative measurements of the strengths and widths of water vapor absorption lines between 8865 and 8915 cm -1 . Alexandrite wavelength determination was obtained with oxygen Aband rotational lines near 765 nm. Similar applications and studies of the water vapor band near 940 nm can be readily carried out by Raman-shifting in deuterium.