Diode-laser measurements of temperature-dependent half-widths of H 2O transitions in the 1.4 μm region

Abstract

Two distributed-feedback InGaAsP diode lasers have been used to perform spectrally resolved measurements of H 2O transitions near 1.4 μm. Line-shape analyses of the recorded absorption spectra yielded the temperature-dependent self-, N 2-, and CO 2-broadened half-widths. Room-temperature (296 K) half-widths for eight rovibrational transitions in the v 1 + v 3 and 2 v 1 vibrational bands were determined from measurements recorded in a variable pathlength (0.4–10 m) multi-pass cell. The temperature dependence of the half-widths for four of the transitions were determined from measurements conducted in a heated static cell over a temperature range of 400–1000 K. The room-temperature half-widths and temperature exponents were determined to an average accuracy of +8% − 6% and ± 9% , respectively, and are in good agreement with theoretical calculations and published half-widths for transitions with the same rotational quantum numbers.