  We present high resolution (R = 90,000) mid-infrared spectra of M dwarfs. The
mid infrared region of the spectra of cool low mass stars contain pure
rotational water vapour transitions that may provide us with a new methodology
in the determination of the effective temperatures for low mass stars. We
identify and assign water transitions in these spectra and determine how
sensitive each pure rotational water transition is to small (25 K) changes in
effective temperature. We find that, of the 36 confirmed and assigned pure
rotational water transitions, at least 10 should be sensitive enough to be used
as temperature indicators.
