High-brilliance Free Electron Lasers (FELs) greatly increase the range of experimental conditions and physical phenomena accessible in photoionization studies of atoms, molecules and clusters.
The efficient exploitation of their qualities poses a challenge for the development of experimental techniques, and imaging techniques have emerged as dominant tools for their ability to collect as much information as possible.
In the framework of Atomic, Molecular, Optical, and Cluster Science, spectral purity, tunability, low timing jitter, near-transform-limited pulses are only some of the specifications of an ideal light source.
Such specifications are met by the Free Electron Laser FERMI in Trieste thanks to its seeded design [1,2].
At FERMI, the above fields of research are covered by the Low Density Matter beamline (LDM) [3,4] whose design and scientific case will be briefly presented.
We will highlight the most recent results obtained at LDM in two quintessential experiments: coherent control, and molecular alignment. In the first experiment we control the photoelectron angular distribution of an atomic target by adjusting
with attosecond resolution the relative phase of two coherent light pulses of commensurate wavelengths .
In the second experiment OCS molecules are impulsively aligned using 200 fs NIR laser pulses; the resulting rotational dynamics are probed using Coulomb explosion following ionization with time-delayed XUV pulses above the Sulphur 2p edge .
This opens the way to imaging experiments on aligned molecular targets at the LDM beamline.
The results originate from the joint effort of many international research groups, whose work is gratefully acknowledged.
This work was partially supported by XFEL strategy program of MEXT, CNR-JSPS bilateral program, JSPS fellowship, TAGEN project, Five-Star alliance.
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 M. Di Fraia et al., Phys. Chem. Chem. Phys., (2017), Advance Article; doi: 10.1039/C7CP01812F