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Na této stránce můžete najít záznamy přednášek z interního semináře Science Lunch (obědu s vědou) z FZU. Science Lunch je unikátní forma vědeckého semináře, na kterém si posluchači mohou vychutnat oběd a poslechnout si zajímavou přednášku o aktuálním vědeckém tématu z oblasti fyziky. Setkání je určeno primárně postdoktorandům, ale je otevřeno i dalším vědeckým pracovníkům z FZU, kteří mají zájem se pravidelně scházet a diskutovat nejen o odborných tématech.
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- 16. 5. 2024
Ing. Jakub Vícha, Ph.D.
Long-standing discrepancies in cosmic-ray physics at the highest energies
One of the fundamental questions in physics is the origin of the most energetic cosmic rays. This has been obscured mainly by uncertainties in their mass composition arising from the modelling of hadronic interactions in the air showers that these particles induce. For some time now, discrepancies between model predictions and measured air-shower data have been complicating our efforts. In this talk, I will discuss these discrepancies, their implications for key questions in cosmic ray physics, and recent advances in the field.
- 18. 4. 2024
Ing. Tomáš Neuman, Ph.D.
Theory of scanning-tunneling-microscope-induced luminescence in organic dye molecules
I will present a theoretical perspective on a microscopy technique that combines the atomic-scale resolution of a scanning-tunneling microscope (STM) with optics. I will explain how this method, taking advantage of phenomena such as the optical Stark shift or plasmonic Purcell effect, can reveal excited-state properties of nanoscale samples with unprecedented spatial resolution. Besides introducing the method and the mechanism of STM-induced luminescence (STML) applied to dye molecules, I will show theoretical considerations concerning some of its applications and extensions, such as the study of vibronic features in the STML spectra and imaging or a theoretical view on correlated photon emission from electrically driven organic molecules in an STM.
- 21. 3. 2024
Ing. Barbora Špačková, Ph.D.
Shedding light on single molecules
Historically, instruments of increasing precision, born from advancements in physics and technology, have transformed our knowledge of life's fundamental components. But only the recent development of single-molecule tools allowed us to dissect the complexities of biological processes at the most fundamental level. However, traditional single-molecule approaches often require modifications to the molecules under study which can perturb their natural function or structure. Addressing this, we have recently introduced an innovative label-free optical microscopy technique that allows for the direct observation of individual biomolecules in their natural state. This technique can visualize biomolecules as small as a few nanometers across, freely moving in solution, and provides quantitative measurements of each molecule's size, weight, and conformation. The further development of this technique will be a key focus of the newly established Dioscuri Centre for Single-Molecule Optics at the Institute of Physics, set to open in July 2024, with the aim of enriching our understanding of biological nano-universe.
- 29. 2. 2024
Ana Sánchez Grande, PhD.
Recent advances in on-surface synthesis of carbon-based π-magnetic nanomaterials
In the last decades an emerging field, named on-surface synthesis (OSS), has attracted enormous interest in the scientific community due to its capability to synthesize unprecedented carbon-based nanomaterials, overcoming intrinsic limitations related to solution chemistry. OSS consists of a bottom-up approach where molecular precursors are sublimed onto a surface under ultra-high vacuum conditions (UHV), and subsequently an external stimulus is applied to the sample in order to induce a chemical reaction towards the formation of the targeted product. The stabilizing role of the surface and the UHV provide ideal conditions to synthesize highly reactive carbon-based π-magnetic nanomaterials. Scanning probe microscopy techniques offer the possibility of performing a comprehensive characterization of the products regarding their structural, electronic, and magnetic properties. In this seminar, we will review the main advances achieved in the OSS field, particularly those related to the synthesis of carbon-based π-magnetic nanomaterials.
- 18. 1. 2024
Ing. Jaroslav Nejdl, Ph.D.
The Nobel Prize in Physics 2023: high-order harmonics and attosecond pulse generation
This year, the Nobel Prize in Physics was awarded to a trio of physicists for their experimental work in the field of generating high-order harmonic generation and isolated attosecond pulses. In this seminar, we will introduce the physical principles of generating such pulses, utilizing the interaction of powerful femtosecond lasers with rare gases. Furthermore, we will outline how the generated pulses can be employed to study the very rapid dynamics of electron shells in atoms and molecules or for the direct measurement of evolution of the electromagnetic field in the visible part of the spectrum.
- 2. 2. 2023
Gwladys Steciuk, PhD.
Assessing environmental challenges of post-mining minerals using 3-dimensional electron diffraction
The mining of uranium ore as a source of energy and other metals has not been just beneficial. Today, there is a need to effectively cope with the aftermath of ore mining and processing. In ore deposits, supergene minerals are formed as a result of weathering processes and they serve as a temporary or final sink for toxic elements, otherwise released into the environment. To assess and predict the behavior and the mobility of elements during weathering, detailed knowledge of the structure of post-mining supergenes combined with physical and chemical properties is of great importance. Until recently, a large portion of supergene minerals’ structures remained overlooked as they do not meet the criteria for conventional analyses by X-ray methods. A recent approach to accessing the structural information at the nanoscale consists in using the 3-dimensional electron diffraction techniques in a transmission electron microscope.
- 23. 3. 2023
Martin Šilhavík, Ph.D.
2D & 3D Graphene: Which is Better?
Graphene in 2D form exhibits extraordinary properties. However, its thickness is only ≈0.35 nm, which is highly impractical for many macroscopic devices and does not suit every application. To overcome this barrier, we have created 3D porous architectures of graphene from discrete graphene sheets without restacking them. Now comes the important question: Will 3D graphene have the same properties as 2D graphene and which is better? You will hear the answer to the question in the March Science Lunch.
- 25. 5. 2023
Ing. Marek Vronka, Ph.D.
Multidimensional transmission electron microscopy
Scanning transmission electron microscopy (STEM) is widely used for imaging, diffraction, and spectroscopy of materials down to atomic resolution. Recent advances in detector technology and computational methods have enabled experiments to reach a new level of information via recording a full image of the STEM probe at every probe position, either in diffraction or real space. I will demonstrate our recent results using modern methods such as scanning nanodiffraction combined with electron energy loss spectroscopy, phase, orientation, and strain mapping. Moreover, I will outline the current state-of-the-art methods, including differential phase contrast, ptychography, and others, and illustrate the new prospects these techniques could bring to materials analysis at the nanoscale.
- 25. 10. 2023
RNDr. Pavel Galář, Ph.D.
Quantum dots: when size matters
This year, the Nobel Prize in Chemistry was awarded to three scientists for the discovery and synthesis of quantum dots (QDs). Why? Because they found a new way how to significantly modify the basic properties of bulk materials. Properties of matter are defined by their chemical composition and structure. However, when its size drops below the exciton Bohr radius (2 - 50 nm, QDs), the electronic states, chemical reactivity and mechanical properties of the matter are being altered, which manifests itself in many ways: e.g. the bandgap expands (size sensitive PL emission/absorption), the surface reactivity increase and the melting temperature decrease. We can even observe switching from indirect to direct bandgap. These effects are caused by the combination of the so-called quantum confinement effect and high surface/volume ratio. While the synthesis of high-quality QDs is still challenging, they have already found a wide range of applications in light conversion/generation, energetics, bio-imagining and medicine.
- 13. 4. 2023
Petr Hauschwitz, Ph.D., MBA
Productive micro/nanostructuring for surface functionalization: case studies and technology overview
Laser structured surfaces may allow attaining innovative surface properties like friction reduction, superhydrophobicity, anti-bacterial and many more. Despite a list of attractive applications and demonstrated capability of lasers to produce them, the speed of laser micro and nanostructuring is still too low with respect to many industry standards. In this presentation several technologies for efficient functionalization will be introduced as well as selected case studies including world records in laser nanostructuring achieved at HiLASE.
- 21. 12. 2023
Mgr. Natalia Podoliak, Ph.D.
Liquid crystals: soft matter with enthralling properties
Self-assembly of organic molecules represents a fascinating playground to create various liquid crystalline (LC) nanostructures. Liquid crystals are known for their unique combination of fluidity and anisotropic properties, which are widely used in technology. The material characteristics are influenced by the chemical composition of the molecules as well as by the molecular organization. Delicate molecular architecture can bring beneficial material properties such as ferro- or antiferroelectricity, photosensitivity, etc. The molecular confinement and the boundary conditions drastically affect the resulting structure and characteristics. Additionally, the amendment of different types of nanostructures, such as nanoparticles, nanorods, and nanoplatelets, are used to bring enhanced properties. Such hybrid nanocomposites of LCs with nanoparticles may serve as a bridge, helping to reach worthwhile multiferroic materials. The emergent technological potential of liquid crystals makes them a promising field of investigation.
- 15. 12. 2022
Matěj Hývl, PhD.
From monocrystalline silicon to third-generation photovoltaic cells
Global warming, energy crisis, security crisis – the solution of many if not most pressing current humankind challenges are connected to finding a new ideal energy source that would be both robust enough to support the huge energy demands of industrial production but also flexible enough to shine in many more specialized applications and environments. Among other so-called alternative sources, photovoltaics is playing a dominant role in the production of green energy. What started with a single monocrystalline silicon diode in 1954 has now grown into a multi-billion industry ranging from highly designed silicon heterojunction solar cells utilizing selective contacts to experimental materials and architectures like organic-inorganic perovskites, kesterites, and their combinations in tandem solar cells. In my talk, I will present the past and presence of photovoltaic research and technology, and show the possible future we are heading towards, with an emphasis on the nano-characterisation of older and brand new kinds of solar cells carried out in our group that might enable us to tackle the world’s insatiable hunger for energy.
- 10. 11. 2022
Vojtěch Trávníček, PhD.
Nobel Prize in Physics 2022: Quantum entanglement – its role in the interpretation of quantum theory and influence on quantum information processing
Quantum entanglement is one of the key phenomena of quantum physics. By its utilization scientists were able to further our understanding of quantum theory and design ways that enhance our computational capabilities and security. Thanks to quantum entanglement ideas like teleportation and quantum internet are no longer in the realm of science fiction. The impact of these new discoveries was so significant that three scientists, namely A. Aspect, J. F. Clauser and A. Zeilinger whose work is closely connected to quantum entanglement, were awarded Nobel Prize in Physics in 2022.