Infrared spectroscopy of (bio)molecules in the gas phase using the free-electron-laser ´FELIX´

Experiments on (bio)molecules in the gas phase - where the interaction with the environment is eliminated or controlled - provide fundamental insight into their structure and function. Recently, the combination of IR and UV hole burning spectroscopy with molecular beam techniques as well as the use of ion trap machines have proven to be extremely valuable techniques to explore the structures of a variety of (bio)molecules. Three examples, ranging from small molecules to biomolecules all rely on the broad-band tunability and the high intensity of a free- electron laser as infrared source are presented in this paper.