  Using the U.C. Berkeley Infrared Spatial Interferometer with an RF
filterbank, the first interferometric observations of mid-infrared molecular
absorption features of ammonia (NH_3) and silane (SiH_4) with very high
spectral resolution (R ~ 100000) were made. Under the assumptions of spherical
symmetry and uniform outflow, these new data permitted the molecular
stratification around carbon star IRC+10216 and red supergiant VY CMa to be
investigated. For IRC+10216, both ammonia and silane were found to form in the
dusty outflow significantly beyond both the dust formation and gas acceleration
zones. Specifically, ammonia was found to form before silane in a region of
decaying gas turbulence (>~ 20 R_star), while the silane is produced in a
region of relatively smooth gas flow much further from the star (>~ 80 R_star).
The depletion of gas-phase SiS onto grains soon after dust formation may fuel
silane-producing reactions on the grain surfaces. For VY CMa, a combination of
interferometric and spectral observations suggest that NH_3 is forming near the
termination of the gas acceleration phase in a region of high gas turbulence (~
40 R_star).
