  Molecular bands of metal oxides and hydrides dominate the optical and
near-infrared spectra of M dwarfs. High-resolution spectra of these bands have
immense potential for determining many properties of these stars, such as
effective temperature, surface gravity, elemental abundances, radial velocity,
or surface magnetic fields. Techniques are being developed to do this but
remain limited by the current availability and accuracy of molecular data and
spectral line lists. This paper reports metal monohydride line lists selected
from near-infrared and visible laboratory data to show that specific bands in
several electronic transitions can be used to identify CrH, NiH, and FeH in M
stars and to determine radial velocities from Doppler shifts. The possibility
of measuring magnetic fields is also investigated for FeH and CrH. We used
systematic cross-correlation analysis between unpolarised spectra from a
selection of M stars and state-specific laboratory line lists. These lists were
generated from a combination of existing data and new laboratory
laser-excitation spectra recorded at Doppler-limited resolution, in zero-field
conditions or in magnetic fields up to 0.6 tesla. Results. We show that
transitions at visible wavelengths in FeH and NiH, usually neglected in the
analysis of the spectra of M-type stars, do in fact contribute to the spectra,
and we demonstrate the influence of magnetic sensitivity on selected
transitions in CrH and FeH. Although the new line lists focus on transitions
recorded at temperatures significantly lower than those of stellar objects,
they remain pertinent because they cover some band-head regions of high
spectral density. FeH bands can provide a useful supplement to atomic lines for
the analysis of high-resolution optical and near-infrared spectra of M dwarfs.
We demonstrate the influence of a magnetic field on CrH signatures around 862
nm.
