Established in 1997, this prestigious national scholarship aims to encourage and recognize young researchers for outstanding research and development achievements and to help them work towards the title of Doctor of Sciences of the Hungarian Academy of Sciences. The Bolyai Scholarship serves as a bridge between HAS, its doctors and the younger generation of researchers, for whom the scholarship ensures predictability in the transitional period until they embark on an independent research career after receiving their PhD degrees. This year, 156 out of the 792 researchers with valid applications have been awarded this support. Three of our physicists – Judit Budai, Balázs Major and Zsuzsanna Pápa – were among the winners.
During her three-year programme, Judit Budai, a senior research fellow in the Ultrafast Nanoscience Group, will study light–matter interactions. In these interactions, the first step is always the excitation of electrons in the medium by light. However, the number of electrons that become excited, the energy they have and the speed at which this energy is transferred to the surrounding system are all important parameters. This process varies considerably in different materials/systems, and these details are essential for the applications.
“My aim is to study such interactions with the ultrafast ellipsometer operating at our institute. I did ultrafast ellipsometry measurements before, but thanks to its unique temporal resolution, this equipment provides an unprecedented method of investigation,” Judit Budai said, explaining her plans. She is primarily interested in how these properties change in different semiconductors, metals and plasmonic systems, how they depend on the structure and composition of the material, on the mechanism of electron excitation, as these processes are different in light–matter interactions and in plasmonic excitations.
Judit also aims to identify cases when high-energy electrons can be excited, as these so-called “hot electrons” can be used in several applications. For example, they can increase the efficiency of catalysis in chemical reactions or improve the performance of solar cells. They can also be useful in any process where light energy is converted. In solar cells, for example, light energy is converted into electricity, while in catalytic processes, light energy is converted into chemical energy. This scholarship will help study these processes in depth and answer the questions that arise, the researcher said.
Zsuzsanna Pápa, Balázs Major, Judit Budai
“Scholarships are intended to encourage specific research projects. The research plan can cover one, two or three years. I have submitted a plan for a two-year programme,” said Balázs Major, senior research fellow of our institute, leader of the HR Attosources Group in the Secondary Sources Division, adding that the funders of the scholarship did not expect applicants to start research projects that were not previously in their portfolios.
Balázs has lately been intrigued by the potential imaging applications of lasers in biological research – more specifically, by the analysis of biological samples, biological building blocks using XUV radiation. He hopes that these applications will allow higher resolution than that achievable with optical microscopes and may approach the resolution of superresolution microscopes.
If successful, the method can avoid one of the disadvantages of X-ray analysis, when the imaging process destroys the sample. The difficulty of superresolution analyses is that you need a marker to label the material. Balázs Major’s method does not require any labelling and radiation would not damage the biological sample either. A secondary source at ELI Beamlines, our partner institute in Prague, would be optimal for the experiments, but the high harmonics generated with our HR laser also hold great promise.
Zsuzsanna Pápa, a member of the Ultrafast Nanoscience Group, has won a two-year scholarship to work on the production and investigation of plasmonic nanoparticles and metal surfaces. In such samples, or along their surfaces, electrons can be made to oscillate synchronously when illuminated by light. This allows the energy of light to be localized near the nanoparticles or on the metal surfaces. What is this technique good for?
“In the case of nanoparticles, this means that we can localize light into a much smaller volume than with optical devices (e.g. lenses). This phenomenon can be exploited to develop sensitive sensors, to make solar cells more efficient. We have already explored many of the fundamental properties of these nanoparticles, now my goal is to design a complex nanoparticle in which we can vary/control where the localization of light should be high. In this way, we will be able to facilitate or inhibit chemical processes at the nanometre scale,” Zsuzsanna Pápa said.
She intends to move towards applications with metal surfaces too. The electron oscillations generated along a metal surface do not stay in one place, as in the case of nanoparticles, but can travel over long distances, like a water wave. This can play an important role in the transfer of information and in light-based circuits. Light allows much faster operations than conventional electronics, but the plasmon wave must be short in time. Our young researcher’s aim is to explore how to produce such waves.
The completion of both tasks will be made possible with the equipment available in the Nanofabrication Laboratory. The electron beam lithography and the focused ion beam devices will enable the fabrication of suitable samples, while the optical near-field microscope will be used for direct visualization of the resulting plasmonic fields.