Researchers have shown that mirror-image substances – so-called enantiomers – can be better distinguished using helical X-ray light.
Targeted manipulations of an atom's magnetic moment are tricky, as the charge currents used for this process are extremely difficult to control . Now, a consortium of collaborators in Germany, Switzerland, Slovenia and Italy reports on a solution to this problem in the cover page article of Physic Review Letters 128, Vol. 15. As it appears, the magnetization of an atomic gas can be altered by high-power lasers using a patterned wave front. The method is promising for studying and manipulating the magnetic properties of matter at the nanoscale.
In contrast to circular dichroism that is dependent on the polarization, helicoidal dichroism induced by a twisted wave front profile is scarcely known. The first evidence of magnetic helicoidal dichroism has now been observed in an experiment using Spiral Fresnel Zone Plates developed at the Paul Scherrer Institut.
X-ray Free Electron Lasers (XFELs) combine the properties of synchrotron radiation (short wavelengths) and laser radiation (high lateral coherence, ultrashort pulse durations). These outstanding machines allow to study ultra-fast phenomena at an atomic level with unprecedented temporal resolution for answering the most intriguing open questions in biology, chemistry and physics.
On August 31st, 2017, SwissFEL reached the next milestone by sending the first X-rays into the Optics Hutch. The Aramis undulators of SwissFEL produced SASE-radiation with 1.2 nm wavelength. The beam entered the Aramis-beamline along the pink beam path of Bernina via two vertical offset mirrors and was detected on the diagnostic photon screen at the end of the Optics Hutch. A stable and well shaped beam with a diameter of 1.5 mm was observed. With the bendable offset mirrors we were able to manipulate the profile to enlarge and reduce the vertical its size from 660 µm (rms) down to 260 µm (rms) without introducing distortions. The gas based intensity and position monitor in the frontend could be calibrated and determined a pulse energy of approximately 5 µJ. We are now looking forward to the next commissioning time in October to commission the monochromatic beam path of Bernina and the second branchline Alvra.
On May 11, 2017 the vacuum chambers of the first two offset mirrors have been closed eventually with the final gold- wire gasket and pumped down to ultra- high vacuum (goal: 1e-9 mbar). These mirrors are the key elements to switch the X-rays between the experimental stations. In pink beam mode they are the only optical elements for the X-rays on their way from the undulator down to the Alvra experiment.
Mirrors are key elements to distribute and shape the Xray beam generated by the undulators of the SwissFEL facility. They are essential tools to guide and focus the light according to the specific users requirements and should do this without noticeable effects on the beam quality. A quantitative measure is the quality of the beam wavefront. The wavefront must be conserved by the optical elements in the SwissFEL beamlines within a fraction of the wavelength which can be as short as one Angstrom in the case of Aramis. There are only few companies in the world, who are able to fabricated such ultraprecise mirrors.
Fermi Surface of Three-Dimensional La1−xSrxMnO3 Explored by Soft-X-Ray ARPES: Rhombohedral Lattice Distortion and its Effect on Magnetoresistance
A research team led by scientists from the Swiss Light Source has for the first time established three-dimensional (3D) electronic structure of the perovskite compound La1−xSrxMnO3 connected with its colossal magnetoresistance. Instrumental for this study has been the use of the new experimental technique of soft-x-ray ARPES, available at the ADRESS beamline, with its intrinsically sharp definition of 3D electron momentum.
SwissFEL, PSI’s x-ray laser, is to render the individual steps of very rapid processes visible. A new method will facilitate especially precise experiments: the individual x-ray flashes are split into several parts that arrive at the object under examination one by one. The principle of the method harks back to the ideas of the earliest high-speed photography.