PAH anions as carriers of the mid-IR emission bands in planetary nebulae

Abstract

We present results of the mid-IR spectra decomposition for planetary nebulae and compact H ii regions in our Galaxy and Magellanic Clouds. The striking correlation between the required PAH component with 7.7 m band shifted to about 7.8 m and electron densities of the modeled sources allows us to argue that this PAH component may be in fact PAH anions (PAH). © 2008 International Astronomical Union.