Widely tunable two-color FEL pulses at FERMI

Program Description

We developed and tested a new configuration of the FERMI FEL source, capable of delivering two-colour time-delayed pulses with independent wavelength tunability over an ample spectral range. This new scheme makes use of two seed laser beams and of a split radiator section to generate two FEL pulses from distinct portions of the same electron bunch. It provides improved conditions for two-colour experiments that require tuning both the pump and the probe to selected core resonances. We tested the source performance in a resonant magnetic scattering experiment on Fe-Ni systems. Widely tuneable two-colour pulses from a seeded FEL have potential for original applications in other fields of condensed matter, atomic and molecular physics.