Laser diode spectroscopy of the H2O isotopologues in the 2.64 μm region for the in situ monitoring of the Martian atmosphere

A near-infrared diode laser spectrometer was used in the laboratory to measure accurately the molecular parameters of the water vapor isotopologues, H216O, H217O, H218O and HDO, in the 2.64 μm region. The work was made with a new-generation distributed-feedback antimonide-based multi-quantum wells diode laser. The selected spectral range as well as the used laser technology is particularly interesting for the in situ monitoring of the water vapor isotopologues in the lower Martian atmosphere. In the laboratory, it was possible to carefully investigate with one single laser, four lines of H216O, two lines of H218O, one line of H217O and one line of HDO. The corresponding line strengths measurements are reported and thoroughly compared to existing databases. Finally, we discuss the design of a version of the TDLAS laser diode sensor, dedicated to the in situ monitoring of the H2O isotopologues on Mars.