X-ray interferometers can measure lengths in the mm range with sub-nm resolution, whereby the almost perfect crystal grid of high-purity silicon is used as a length scale. The dimensions of any sub-µm-structured samples are thereby compared with the lattice parameter of silicon (?0~0.543... nm) which has been determined very precisely within the scope of the project for the new definition of the Avogadro constant. For metrological applications in connection with scanning probe microscopes, such measurements are of great importance.
Up to now, a further spreading of this method had, however, been impeded by the low translation velocities of only 1 nm/s to 10 nm/s. They are due to the limited intensity of typical laboratory X-ray sources: the necessary filtering of the periodic interference signal leads to a reduction in contrast which, in a classic measurement, requires a slow translation of the interferometer.
In a quantum-mechanical sense, however, interference occurs also in a strongly "diluted" stream of X-ray photons: Regarded as a wave packet, even single photons follow in their temporal impact on the detector the same probability which, in the case of sufficiently intense X-ray light, leads to the continuous signal whose period one wants to determine. This well-known quantum-mechanical fact is now exploited for a specific purpose: if one protocols the times at which the single photons hit the detector, one can, by means of a subsequent Fourier transform of this time series, determine very precisely the frequency at which the lattice periods were passed. At constant velocity, it is then possible to reconstruct the path information, and one obtains the same information as with the classic measurement, but in a much shorter amount of time.
Thus, translation velocities of up to 1000 nm/s could be realised. This method will in future not only be used in further improved measuring arrangements for the determination of the lattice parameter of silicon, but also for other length measurements in nanotechnology.
Erika Schow | alfa
NASA's Fermi catches gamma-ray flashes from tropical storms
25.04.2017 | NASA/Goddard Space Flight Center
DGIST develops 20 times faster biosensor
24.04.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
25.04.2017 | Physics and Astronomy
25.04.2017 | Materials Sciences
25.04.2017 | Life Sciences