NUST MISIS scientists in cooperation with international colleagues have managed to observe the inner structure of photonic crystals, the most promising materials of the 21st century; the work is published in the Small journal
With the help of electronic microcopy, scientists have managed to track defects in the surface of two-dimensional photonic crystals, but there was a problem with bulk photonic crystals. There was no way for scientists to research the inner parts of these unusual crystals, in which the order occurred at a tenth of a nanometer, or even in substances -- the order arose at a tenth and a hundredth of a nanometer. Hence, scientists have been searching for a method to better measure these crystals for some time.
"Ilya Besedin, an engineer from the NUST MISIS Laboratory of Superconducting Metamaterials, jointly with a group of scientists from Germany, the Netherlands, and Russia, for the first time, has demonstrated that there is a method of non-destructive analysis of the inner structure of the substance, which cannot be seen with the use of conventional X-rays. The new system will help to create microprocessors for optical computers. It`s not a coincidence that the work was published in Small journal, one of the most cited journals in the field of biotechnologies, biomaterials, and interdisciplinary engineering", said Alevtina Chernikova, Rector of NUST MISIS.
As Ilya Besedin stated, their research group led by Professor Ivan Vartanyants from MEPhI has applied the recently developed method of ptychographic to photonic crystals. The method's essence is that the substance is illuminated by x-ray radiation of an exactly defined wave (coherent). Sources of such radiation are called synchrotrons, and their experiments were conducted during the third generation synchrotron commissioned to research particle physics in Germany (DESY).
"With conventional x-rays you can scan either macroscopic or very ordered structures. In our case, for structures of polystyrene spheres of an almost micron size, the accuracy of the image will be even worse than in fluoroscopy. At least, it won`t be possible to discern a single object [smaller] than a micron", said Ilya Besedin.
Comparing fire and led is a good analogy to understand the difference in the quality of conventional x-rays and synchrotron. Fire ignites in a wide range of frequencies while led ignites on a strictly determined frequency and in a given direction. Thanks to such a high quality x-ray, Ilya Besedin and his colleagues have managed to "observe" through the mesoscopic structure the structures of substances where the sequence is found only at a distance of tens and hundreds of nanometers. Most importantly, scientists have managed to identify internal defects of mesoscopic structures.
As Ilya Besedin explained, if the crystal is perfect, the beam can pass through or be reflected. However, because of defects, the beam might deviate from a straight line.
"By knowing information about packaging defects, we can understand the logic through which the beam changes its direction. This means we can try to collect logical designs based on photonic crystals. Another thing is that we are not able to control the formation of these defects, we can only try to reduce [the defects] at the macro level", explained Besedin.
"A photonic crystal is like a waveguide for the light, only better. The waveguide is almost impossible to bend, and it's impossible to create photonic microchips on waveguides. A photonic crystal is most suitable for the creation of integral optical microchips where the light can spread where the developers need it to", noted Ilya Besedin.
According to him this is why the main value of this work is in the analysis of photonic crystals` inner structure with the help of ptychography.
"We have shown that now, with the help of x-rays, we can observe defects in periodic mesoscopic structures. The next stage of specification is to expose these structures to radiation with an x-ray laser. This can give a more accurate picture of the internal structure, but there are also some difficulties. The laser beam is, by definition, more powerful than just an outgoing one from synchrotron. While increasing the power, the probability of destroying the investigated structure increases significantly, which is not [good]. Ptychography also allows researchers to study the inner structure of a crystal without destroying it. That is why such a method will definitely find its application", Besedin concluded.
Lyudmila Dozhdikova | EurekAlert!
Spider silk key to new bone-fixing composite
20.04.2018 | University of Connecticut
Diamond-like carbon is formed differently to what was believed -- machine learning enables development of new model
19.04.2018 | Aalto University
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Physics and Astronomy
20.04.2018 | Physics and Astronomy