Solid state components of varying compositions in the outflow of the Red   Rectangle
  We present high resolution Spitzer spectroscopy of several pointings in the outflow of the Red Rectangle. Besides the resonances due to the C-rich PAHs, the spectra show a wealth of new emission bands, in particular in the 13-19.5 micron range. We argue that these bands are due to solid state components, and show that simple oxides of a varying composition show a good match to the data. The presence of these O-rich species in the supposedly C-rich outflow is unexplained. 
F. Kemper, J. D. Green, E. Peeters