  We have detected [Fe II] 17.94 um and 24.52 um emission from a sample of M
supergiants using TEXES on the IRTF. These low opacity emission lines are
resolved at R = 50, 000 and provide new diagnostics of the dynamics and
thermodynamics of the stellar wind acceleration zone. The [Fe II] lines, from
the first excited term, are sensitive to the warm plasma where energy is
deposited into the extended atmosphere to form the chromosphere and wind
outflow. These diagnostics complement previous KAO and ISO observations which
were sensitive to the cooler and more extended circumstellar envelopes. The
turbulent velocities, Vturb is about 12 to 13 km/s, observed in the [Fe II]
forbidden lines are found to be a common property of our sample, and are less
than that derived from the hotter chromospheric C II] 2325 Angstrom lines
observed in alpha Ori, where Vturb is about 17 to 19 km/s. For the first time,
we have dynamically resolved the motions of the dominant cool atmospheric
component discovered in alpha Ori from multi-wavelength radio interferometry by
Lim et al. (1998). Surprisingly, the emission centroids are quite Gaussian and
at rest with respect to the M supergiants. These constraints combined with
model calculations of the infrared emission line fluxes for alpha Ori imply
that the warm material has a low outflow velocity and is located close to the
star. We have also detected narrow [Fe I] 24.04 um emission that confirms that
Fe II is the dominant ionization state in alpha Ori's extended atmosphere.
