The world's sharpest X-ray beam shines at DESY. At the X-ray light source PETRA III, scientists from Göttingen generated a beam with a diameter of barely 5 nanometres – this is ten thousand times thinner than a human hair. This fine beam of X-ray light allows focusing on smallest details.
This is the reconstruction of the two-dimensional focus field. The intensity is color coded.
Credit: Image: University of Göttingen
This is an electron micrograph of the micro lens on the tip of a needle. The lens has a diameter of just two microns (thousandths of a millimeter).
Credit: Image: University of Göttingen
The research groups of Professor Tim Salditt from the Institute of X-ray Physics and of Professor Hans-Ulrich Krebs from the Institute of Materials Physics of the University of Göttingen published their work in the research journal Optics Express.
High-energy (hard) X-ray light cannot be focused as easily as visible light by using a burning glass. "Instead of a common lens, we use a so-called Fresnel lens which consists of several layers," explains co-author Dr. Markus Osterhoff. The central support is a fine tungsten wire with the thickness of only a thousandth of a millimetre. Around the wire, nanometre-thin silicon and tungsten layers are applied in an alternating way.
The physicists then cut a thin slice from the coated wire. "This slice has 50 to 60 silicon and tungsten layers, comparable to growth rings of a tree," explains team member Florian Döring. "And the layer thicknesses have to be extremely precise," adds Christian Eberl. The two PhD students have optimized the different fabrication steps.
The wire slice with a size of only about two thousandths of a millimetre is used as a lens. However, it does not diffract light like a glass lens but scatters it like an optical grid generating a pattern of bright and dark patches. In this case, the thickness of the layers is selected in such a way that the bright areas of the diffraction pattern coincide at the same spot.
The more precise the lens is fabricated, the sharper becomes the X-ray focus. With this method, the physicists obtained an X-ray beam of 4.3 nanometres (millionth of a millimetre) diameter in horizontal direction and 4.7 nanometres diameter in vertical direction. Until recently it was even debated whether fundamental limits of X-ray optics would stand against such small focal widths. The outstanding brilliance of DESY's X-ray light source PETRA III helped to make a usable nano focus possible.
The fine X-ray beam opens up new possibilities for materials science, e.g. the investigation of nano wires to be used in solar cells. "Usually, when investigating the chemical composition of a sample, the beam size limits the sharpness of the image. Before this experiment, this limit was at about 20 nanometers", said DESY researcher Dr. Michael Sprung, responsible scientist for the PETRA measuring station P10, where the experiments are carried out.
As a next step, the scientists want to improve the performance by depositing the layers on ultrathin and extremely uniform glass fibres. Moreover, they plan to scan first nanoscopic structures with their novel ultra-sharp beam. In the future, such a lens should help to create foci of ultimate flux density with free-electron laser (FEL) radiation.
Dr. Thomas Zoufal | EurekAlert!
Further Improvement of Qubit Lifetime for Quantum Computers
09.12.2016 | Forschungszentrum Jülich
Electron highway inside crystal
09.12.2016 | Julius-Maximilians-Universität Würzburg
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine