14. Feb. 2024

Michal Horák from the research group Preparation and Characterization of Nanostructures, led by Prof. Tomáš Šikola at CEITEC BUT, has been awarded the prestigious Austrian Fritz-Grasenick-Preis Prize. In the interview, he describes his successful research in the field of plasmonics of non-noble metals. His research project with gallium nanoparticles has the potential to push the boundaries in broad-spectrum absorption of sunlight. In conjunction with a solar cell, the nanoparticles could serve as an additional absorption layer, contributing to more efficient use of solar energy and increasing the efficiency of solar cells. The award from his Austrian colleagues comes in recognition of his innovative approach and significant contribution to the international scientific community.


This is not your first award, what other awards have you received?

Awards are an integral part of my scientific career. I have participated in various competitions aimed at young and emerging scientists and PhD students, which I consider a meaningful way to advance in my scientific endeavors. I applied to competitions organized by the Czechoslovak Microscopy Society (CSMS). I have seen success with my dissertation which was regarded the best. Subsequently, I received a two-year scholarship for young scientists from the CSMS and Thermo Fisher. I also received another award from the Jan Marci Spectroscopic Society in the category of published papers and collections of papers, intended for authors under 35 years of age. Additionally, in 2020, I received an honorable mention from the Czech Physical Society as part of the Milan Odehnal Prize.


Now you are also the first Czech to win the Austrian Fritz-Grasenick-Preis Prize; what do you think of this achievement?

I am happy about the Fritz-Grasenick-Preis award I received last year, and I consider it a significant success. It should be emphasized that this award is given to members of the Austrian Microscopy Society, of which I became a member in 2018. The competition has always been very strong, and I succeeded after about two or three years of participation.


Of all the awards, is this the most important one for you?

I would say so. Or among the most important ones. I would place it probably on a similar level to the award I received at the virtual conference in America, which arrived by mail. That was an award for a postdoc for one of the best abstracts. For me, these international achievements hold a little more value than others because the competition is much higher – it's worldwide. It gives me a sense of where I stand on the international scale.


Where do awards like this take you? Do you establish new contacts, for example?

Not necessarily, because I've been in contact with my Austrian colleagues since 2014, when I spent six months there during an Erasmus program. It was at that time that I learned how to use electron microscopes. It's more about being recognized for doing honest work that has significance and impact.


Can you introduce the winning project?

The publication was about gallium nanoparticles, which have a significant research history in our country. Colleagues at the Institute of Physical Engineering specialise in gallium deposition and are able to deposit gallium nanoparticles of different sizes using effusion cells (a tool for precise and controlled deposition of atoms or molecules onto specific surfaces or substrates). We decided to deposit gallium nanoparticles onto thin silicon nitride membranes, which are ideal for electron microscopy. For microscopy purposes, we needed a thin sample, so we used silicon nitride with a thickness of approximately 50 nanometers and placed gallium nanoparticles on top of it. These nanoparticles can be thought of as slightly flattened spheres that are placed on a membrane and have a diameter of 10 to 200 nanometers. The main focus of our paper was to investigate the optical properties of this system, specifically the localized plasmonic resonances, which are the movements of free electrons within these metal nanoparticles.


What did you find out?

A very interesting finding was that resonances are present and show a relatively high intensity, which can be effectively detected by electron microscopy. Another important finding was that this resonance can be tuned depending on the particle size from ultraviolet light to visible red spectrum. We anticipate that as the particle size increases, we could reach into the infrared. This gives us a very broad-spectrum system.


Where could the new findings be applied?

The first promising application is in the field of broad-spectrum absorption. In this way, nanoparticles could absorb energy from sunlight across the entire visible spectrum, including the UV and near-infrared regions. This property could be used in conjunction with a solar cell, where it would serve as an additional absorption layer, which could increase its efficiency.


So it could generate more energy? What other potential uses do you see?

Exactly. Gallium particles are often utilized in sensors. For instance, in Raman spectroscopy, they enhance the signal. Additionally, being a biocompatible material, gallium can also be utilized in electrochemistry – allowing us to study DNA binding on its surface. In this domain, we can also utilize light illumination to provide energy to these microspheres, influencing their binding properties.


What direction will you take next?

I'm essentially continuing my research in electron microscopy and plasmonics – which means gallium nanoparticles are more-or-less a closed chapter for me. It's common scientific practice to build upon somebody else’s results. Myself, I have a follow-up project where I investigate the phase transformation of gallium.


What is a research priority for you now?

Currently, our highest priority is vanadium dioxide, a material undergoing thermal phase transformation. At room temperature, it behaves as a dielectric (insulator – it has the ability to disrupt or slow down the transfer of electrical charge), but above 70°C, it becomes metallic (conductive). This property enables us to control plasmonic resonances within the material through temperature manipulation. Additionally, we're exploring other plasmonic materials, including unconventional ones like bismuth. While bismuth is known as a heavy metal, we aim to investigate its plasmonic properties to uncover potential applications.


You have been mentioning plasmonics. How would you explain it in simple terms?

Plasmonics is the study of plasmonic resonances in metals. This involves the oscillations of free electrons, typically confined within nanoparticles.


Could you describe what working with metals looks like?

To work with metal, I first need to nanostructure it – creating nanoparticles of a defined size and shape. Then, I need to assemble them in a particular way. This involves exposing them to either light or electrons, causing them to oscillate. As a result, the bundle with which I build up the excitation loses the corresponding energy that was used to excite it, and I can see what I have constructed. Alternatively, we can then observe, for example, a change in the colour of the material.


What would you like your next achievement to be?

This year, my goal is to resubmit a standard GACR project. After four years, I've decided to change the topic and focus on a new project in the field of plasmonics involving non-noble metals. I believe this topic has the potential to attract attention. Over the past four years, I've attempted to secure funding for a project on gold-based plasmonics, specifically focusing on the lightning conduction phenomenon. Despite receiving favourable ratings three out of four times, the project has not been funded.


Why do you think non-noble metals might be more interesting?

They offer something exotic and new, which can be intriguing.

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