  Long-slit 8-13 um spectroscopy of the nebula around NGC 1333 SVS reveals
spatial variations in the strength and shape of emission features which are
probably produced by polycyclic aromatic hydrocarbons (PAHs). Close to SVS 3,
the 11.2 um feature develops an excess at ~10.8-11.0 um, and a feature appears
at ~10 um. These features disappear with increasing distance from the central
source, and they show striking similarities to recent laboratory data of PAH
cations, providing the first identification of emission features arising
specifically from ionized PAHs in the interstellar medium.
