Learn More
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(More)
Nonlinear photoemission from a silver single crystal is investigated by femtosecond laser pulses in a perturbative regime. A clear observation of above-threshold photoemission in solids is reported for the first time. The ratio between the three-photon above-threshold and the two-photon Fermi edges is found to be 10(-4). This value constitutes the only(More)
We report on new opportunities for ultrafast science thanks to the use of two-colour extreme ultraviolet (XUV) pulses at the FERMI free electron laser (FEL) facility. The two pulses have been employed to carry out a pioneering FEL-pump/FEL-probe diffraction experiment using a Ti target and tuning the FEL pulses to the M(2/3)-edge in order to explore the(More)
Significant changes of the optical properties of semiconductors can be observed by applying strong electric fields capable to modify the band structure at equilibrium. This is known as the Franz-Keldysh effect (FKE). Here we study the FKE in bulk GaAs by combining single cycle THz pumps and broadband optical probes. The experiments show that the phase(More)
Fluctuations of the atomic positions are at the core of a large class of unusual material properties ranging from quantum para-electricity to high temperature superconductivity. Their measurement in solids is the subject of an intense scientific debate focused on seeking a methodology capable of establishing a direct link between the variance of the atomic(More)
The non-equilibrium approach to correlated electron systems is often based on the paradigm that different degrees of freedom interact on different timescales. In this context, photo-excitation is treated as an impulsive injection of electronic energy that is transferred to other degrees of freedom only at later times. Here, by studying the ultrafast(More)
Photoemission from image potential states on Ag(100) is investigated using angle resolved multiphoton photoemission induced by 150 fs laser pulses. For the first time we demonstrate that image potential states populated by indirect transitions can be observed with light polarized parallel to the plane of incidence and light polarized normal to the plane of(More)
A single-crystal X-ray structure study of gadolinium triiron tetraborate, GdFe3(BO3)4, at room temperature and at 90 K is reported. At room temperature GdFe3(BO3)4 crystallizes in a trigonal space group, R32 (No. 155), the same as found for other members of the iron borate family RFe3(BO3)4. At 90 K the structure of GdFe3(BO3)4 transforms to the space group(More)
  • 1