Dissecting starburst galaxies with infrared observations

The infrared regime contains a number of unique diagnostic features for probing the astrophysics of starburst galaxies. After a brief summary of the most important tracers, we focus in detail on the use of emission lines to probe the upper part of the main sequence in a young superstarcluster in the Antennae, and the compact, dusty starburst in the nucleus of the nearby ultraluminous infrared galaxy Arp220