The New IR FEL Facility at the Fritz-Haber-Institut in Berlin

A mid-infrared oscillator FEL has been commissioned at the Fritz-Haber-Institut. The accelerator consists of a thermionic gridded gun, a subharmonic buncher and two S-band standing-wave copper structures. It provides a final electron energy adjustable from 15 to 50MeV, low longitudinal (<50 keV-ps) and transverse emittance (<20 mm-mrad), at more than 200 pC bunch charge with a micro-pulse repetition rate of 1 GHz and a macro-pulse length of up to 15µs. Pulsed radiation with up to 50 mJ macro-pulse energy at about 0.5% FWHM bandwidth is routinely produced in the wavelength range from 4 to 48µm. Regular user operation started in Nov. 2013 with 6 user stations. The user experiments include nonlinear spectroscopy of solids, spectroscopy of bio-molecules (peptides and small proteins), which are conformer selected in the gas-phase or embedded in superfluid helium nano-droplets at 0.4 K, as well as vibrational spectroscopy of mass-selected metal-oxide clusters and protonated water clusters in the gas phase.