The authors find using resonant and non-resonant x-ray diffraction on an x-ray free electron laser that the structural distortion and the underlying electronic structure of the charge density wave in TiSe2 show different energetics at ultrafast timescales. This indicates that the lattice distortion stabilizes the charge density wave.
Scientists pioneer an approach called self-referenced streaking, clocking Auger electrons with sub-femtosecond resolution. The breakthrough will unlock the broader potential for attosecond time resolution at X-ray free-electron lasers
Excitation of coherent phonons using light is an emerging approach for investigating condensed matter physics. It has the potential not only to reveal the dynamics of collective lattice vibrations but also to tailor them for the ultrafast control over the electronic, magnetic, and structural properties in solids. The optical phonons, in most solids, lie primarily in the spectral region between 1 and 10 THz. Unlike conventional laser sources, coherent radiation at these frequencies allows us to study time-resolved lattice displacements with only minor deposition of heat or generation of hot electrons. However, the available high-field terahertz sources, with their quasi-single cycle temporal shape and broadband spectrum, cannot be used to excite the individual phonon modes. By contrast, the challenge of understanding the transient dynamics of low-energy excitations calls for novel sources of narrow-band terahertz radiation at high intensities that can be tuned to the individual phonon resonances. Moreover, with strong enough fields tuned precisely to a phonon resonance, non-linearities in the material can be targeted and potentially exploited.
Exotic atoms, in which electrons are replaced by other particles, allow deep insights into the quantum world. After eight years, an international group of scientists have succeeded in a challenging experiment conducted at PSI’s pion source: they created an artificial atom called “pionic helium”.
In order to achieve high-brillance and ultra-short FEL pulses, a flat current profile of the electron bunch is required. We achieve this by temporal shaping of the photo-cathode laser. From a femtosecond Gaussian pulse, we produce a picosecond long, flat-top laser pulse. At low charge, the photo-cathode laser pulse temporal profile is directly transferred into the electron bunch temporal profile.
LNO has just installed a new CEP-capable mid-IR source for SiwssFEL experiments. The new source will enable a new class of experiments focused on understanding the unique properties of nonequilibrium driven states.
The Einstein–de Haas effect, first demonstrated more than a century ago, provides an intriguing link between magnetism and rotation in ferromagnetic materials. An international team led by ETH physicist Steven Johnson now established that the effect has also a central role in ultrafast processes that happen at the sub-picosecond timescale — and thus deliver fresh insight into materials that might form the basis for novel devices.
With the X-ray laser SwissFEL, researchers at PSI want to produce movies of biomolecules in action. This can reveal how our eyes function or how new drugs work.
On the 17th of December 2017 SwissFEL saw its first pilot experiment in the Alvra experimental station of the SwissFEL ARAMIS beamline.