Mid-Infrared Diagnostic Diagrams and the Starburst-AGN Connection

The mid-infrared regime is little affected by extinction, and it contains a plethora of spectroscopic information.The Infrared Space Observatory (ISO)has provided access to this wealth of information.Here I present new results from a study of ISO-SWS spectra of about 30 AGNs, concentrating on diagnostic digrams to distinguish between star formation and AGNs as energy source in dusty galaxies (such as ULIRGs), and to discuss the Starburst-AGN connection in general. Further results and all details of this study can be found in Sturm et al.(2002).