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

E. Allaria , F. Bencivenga (1) , R. Borghes (1) , F. Capotondi (2) , D. Castronovo , P. Charalambous , P. Cinquegrana , M. B Danailov , G. de Ninno (3) , A. Demidovich , S. Di Mitri , B. Diviacco , D. Fausti , M. Fawley , E. Ferrari , L. Froehlich , D. Gauthier (4) , A. Gessini , L. Giannessi (5) , R. Ivanov , M. Kiskinova , G. Kurdi , Benoît Mahieu (6, 7, 8) , N. Mahne (9) , I. Nikolov , C. Masciovecchio (1) , E. Pedersoli , G. Penco , L. Raimondi , C. Serpico , P. Sigalotti , S. Spampinati , C. Spezzani (6) , C. Svetina (1) , M. Trovo (6) , M. Zangrando (6)

1 Sincrotrone Trieste
2 INFM - NEST-INFM
3 School of Applied Sciences
4 TIMA - Techniques de l'Informatique et de la Microélectronique pour l'Architecture des systèmes intégrés
5 ENEA - Italian National agency for new technologies, Energy and sustainable economic development [Frascati]
6 Elettra Sincrotrone Trieste
7 University of Nova Gorica
8 LOA - Laboratoire d'optique appliquée
9 IOM - CNR Istituto Officina dei Materiali

Exploring the dynamics of matter driven to extreme non-equilibrium states by an intense ultrashort X-ray pulse is becoming reality, thanks to the advent of free-electron laser technology that allows development of different schemes for probing the response at variable time delay with a second pulse. Here we report the generation of two-colour extreme ultraviolet pulses of controlled wavelengths, intensity and timing by seeding of high-gain harmonic generation free-electron laser with multiple independent laser pulses. The potential of this new scheme is demonstrated by the time evolution of a titanium-grating diffraction pattern, tuning the two coherent pulses to the titanium M-resonance and varying their intensities. This reveals that an intense pulse induces abrupt pattern changes on a time scale shorter than hydrodynamic expansion and ablation. This result exemplifies the essential capabilities of the jitter-free multiple-colour free-electron laser pulse sequences to study evolving states of matter with element sensitivity.

Domains: Optics [physics.optics]; Accelerator Physics [physics.acc-ph]; Atomic Physics [physics.atom-ph]

E. Allaria, F. Bencivenga, R. Borghes, F. Capotondi, D. Castronovo, et al.. Two-colour pump–probe experiments with a twin-pulse-seed extreme ultraviolet free-electron laser. Nature Communications, 2013, 4 (1), ⟨10.1038/ncomms3476⟩. ⟨hal-01859817⟩