The Soft X-ray Laser project is the result of an initiative by the Swedish user community that requests enhanced capabilities at MAX IV to deliver coherent ultrashort pulses in the soft X-ray range. A Conceptual Design Study, funded by the Knut and Alice Wallenberg Foundation, MAX IV Laboratory, Uppsala University, Stockholm University, The Royal Institute of Technology (KTH), Lund University, Lund Laser Centre (LLC) and the Stockholm-Uppsala FEL Centre was recently completed and will serve as a basis for further discussions with the user community as part of the overall MAX IV strategy to provide Sweden with state-of-the-art research tools.
What is a Free Electron Laser?
A free-electron laser (FEL) produces extremely brilliant, short pulses of light. It operates by letting bunches of electrons pass through very long, magnetic undulator structures. The length of the magnetic structure facilitates stimulated emission, just like in a regular laser, leading to amplification. The light emitted by an FEL is coherent.
The SXL will target the soft X-ray wavelength range 1-5 nm, and specialize in producing extremely short pulses, which will open up new fields of research in ultrafast science.
Four scientific areas are in focus for the SXL from the start
• atomic, molecular and optical physics (AMO)
• condensed matter
• life science
In the field of AMO, the fundamentals of ultrafast charge dynamics can be studied in atoms and molecules. The understanding of such dynamics is important since they play a crucial role in several chemical, biological and physical processes in larger molecular systems. Examples of such processes are photosynthesis and charge transfer through DNA, important for e.g. mutation and development of cancer. The SXL will allow exploring such phenomena using ultrashort pulses and two pulses with different colours in pump-probe or stimulated resonant inelastic scattering experiments.
In chemistry, the SXL will enable us to probe how molecules evolve on timescales of electronic and nuclear motion. Specific research fields that will benefit from the short pulses and pump-probe capabilities of the SXL include heterogeneous catalysis and photovoltaics, both of crucial relevance to attaining an energy sustainable society.
In condensed matter, the SXL will open up possibilities in a number of fields including the study of ultrafast magnetism with far-reaching implication for the understanding of fundamental processes such as ultrafast demagnetization. In this context, the full polarization control allowed by the SXL will be a key feature.
Finally, the SXL will enable various nanoscale imaging techniques in life sciences. Examples are imaging of large heterogeneous objects such as living cells and X-ray scattering in protein solutions, which can help reveal the mechanisms of protein folding and fast conformational changes.
The SXL consists of four parts – the already operating MAX IV linear accelerator, a new 40-m undulator, a corresponding beamline and a set of experimental stations. The SXL thus capitalizes on the capabilities of the MAX IV linear accelerator.