Pump-probe with twin-seeded two-color FEL

The time resolved dynamics of matter under extreme non-equilibrium conditions can be studied by pumping the sample with an intense ultrafast X-ray pulse and probing the system response with a second FEL pulse after a known delay.

Allaria et al., Nature Communications 4, 2476 (2013).

Pump-probe with twin-seeded two-color FEL

Two-color twin FEL pulses can be produced seeding two different zones of the electron bunch with two seed pulses, with controlled wavelength difference and femtosecond delay. FERMI's ondulators are tuned to amplify harmonics of both the seed wavelength and provide two extreme ultraviolet FEL pulses with the same delay and wavelength ratio as the tween-seed.

Two-color femtosecond pump-probe FEL experiments have been carried out impinging, with the two pulses tuned within the Ti M-edge resonance, on a titanium grating which dispersed the pump and probe photons on different regions of a CCD detector.

Performing the experiment at low flux, contributions at both wavelengths are recorded on the detector; at high flux, the strong pump pulse perturbs the titanium electron structure, producing a change in it's optical properties, so that the probe pulse is no longer in resonance and its spot is quenched on the detector.

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Two-colour pump-probe experiments with a twin-pulse-seed extreme ultraviolet free-electron laser.

E. Allaria, F. Bencivenga, R. Borghes, F. Capotondi, D. Castronovo, P. Charalambous, P. Cinquegrana, M.B. Danailov, G. De Ninno, A. Demidovich, S. Di Mitri, B. Diviacco, D. Fausti, W.M. Fawley, E. Ferrari, L. Froehlich, D. Gauthier, A. Gessini, L. Giannessi, R. Ivanov, M. Kiskinova, G. Kurdi, B. Mahieu, N. Mahne, I. Nikolov, C. Masciovecchio, E. Pedersoli, G. Penco, L. Raimondi, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, C. Svetina, M. Trovò, M. Zangrando.

Nature Communications 4, 2476 (2013).

DOI: 10.1038/ncomms3476

Last Updated on Monday, 21 December 2015 10:58