20. June 2023

"I hope I don't say anything stupid, so I don't get fired from my job like Joey from Friends," Antonín Sojka begins his first interview with a laugh. The azure sky and the Californian sun add to the good mood. He has been a postdoctoral fellow at the University of Santa Barbara for almost a year. Even though he never wanted to even get a Ph.D. At CEITEC BUT, he worked on electron paramagnetic resonance (EPR).


Who eventually convinced you to apply for a Ph.D.?

I'll start a bit broadly. I did my BSc and MSc at the Physical Engineering Department of BUT under the supervision of Dr. Michal Pavera, with whom I am now friends. He asked me after my studies if I wanted to join him, and I refused, saying that I needed a change. Then he introduced me to his friend Associate Professor Peter Neugebauer from Germany, who was just starting a new research group at CEITEC BUT. He was a young charismatic scientist. I was very impressed by him, which eventually lured me to the Ph.D. I changed my topic of focus from STM microscopes to electron paramagnetic resonance, which started my studies at CEITEC.

And then you even wanted to continue your studies. 

Yes, it was thanks to CEITEC, which offered a study abroad program. Very few people in the world are doing exactly what I am doing, which is trying to build new spectrometers for electron paramagnetic resonance. Because of that, three years ago I got a month-long fellowship here in California with my current supervisor, professor Mark Sherwin, and we hit it off. Two years after the internship, he contacted me again, saying he was going to do a huge project and if I wanted to join. So here I am. But I also had the opportunity to study in Vienna and work in London.

How do you like Santa Barbara?

It's great here. You think, I'm going west, the culture will be quite similar, but it's completely different. First thing, Americans are supposed to be overweight? That's not true, at least in California. Here, everyone's handsome, fit, athletic. When I came here, I had to start working out too, so my wife wouldn't run away (laughs). Second thing, there's a different team spirit and work ethic. I find people more united. They are only guaranteed five days of vacation a year from the state and about three days of sick leave, which is really nothing. Still, they're cheerful and like coming to work. I meet a factory worker and he smiles, waves, says hello and enjoys it. They're all positive. And they also work from morning till night. We have one young and incredibly smart colleague at the university. He must know he's smarter than all of us put together, but he's not arrogant and he doesn't tower over us. So, arrogance and even envy, which often reigns in the Czech Republic, is definitely not here. It's more about mutual support and belonging. Is one on the team good? Then the whole team is good. And that's their whole philosophy.

What do you do at the university?

I have a few students under me and I'm trying to learn how to lead them. Our goal is to build a new spectrometer. The lab here is unique in that it has a free-electron laser, which is kind of like the particle accelerator at CERN, except it's not as big as a few cities. Imagine the size of one hall. We use this laser to send electrons at high speed along a specific path. When we oscillate them along part of the route, they lose energy and emit it in the form of wavelengths. We can adjust this to emit the wavelength we need. As a result, we are able to obtain enormous power, which we use with the spectrometer to observe various phenomena in physics, in particular to study the magnetic properties of atoms, molecules or proteins. They've had this instrument here for about ten years and it only works at one frequency. My task is to build a new spectrometer that will have more than twice the range and therefore more applications. In addition, this spectrometer will be able to work not only with a change in magnetic field but also in frequency. In designing the new spectrometer, I am also trying to use the knowledge from CEITEC. 

Sounds great. What exactly were you doing in Brno at that time?

My studies focused on the development of electron paramagnetic resonance, a spectrometer for studying samples where there is an unpaired electron, such as paramagnetic substances. Simply put, the electron has a spin that characterizes its magnetic moment. When a magnetic field is applied to this electron and it is simultaneously irradiated at microwave frequency, a resonance occurs that is specific to each sample. And this gives us a lot of information about the whole sample under study, such as what it looks like, what it's made up of, or how far apart the molecules in it are. This is a very well-known method that has been used since the second half of the last century. Normally you have just one frequency and you slowly change the magnetic field until you see the resonance mentioned. In Brno we started to change the frequency very quickly in addition to the magnetic field, which gave us more information about the sample we were studying. This opened the door to very fast processes that cannot be measured with the conventional method. This allowed us to make much faster and more accurate measurements. The limitation of this spectrometer was the low power of the microwave emitting source, especially at higher frequencies.

Can the accelerator at the University of California now help you with more power?

To some extent, yes. But the spectrometer that I am designing in Santa Barbara will operate mainly in the so-called pulsed mode, which needs high power, which we have here at the university thanks to the accelerator. However, the frequency can be changed slowly. And I'm trying to combine that in the proposed instrument so that I have the power and I won't change the frequency very quickly, but the magnetic field, which will add the possibility of being able to study fast (nanosecond) processes in the sample. It's quite challenging to understand when you don't "live" this scientific field on a daily basis. Even my students have to concentrate hard enough to understand everything.

What would be the application of your innovation?

Thanks to the high performance, we can wake up processes in the sample and then scan them quickly, which we wouldn't be able to do otherwise. So, we have an accurate idea of the relaxation of the electron's magnetic spin. It could be used, for example, to develop quantum computers, new data storage devices. However, we're talking about the distant future. But I have one good example to explain it, and that's in magnetic resonance. Everybody knows it. MRI is terribly slow because its method is quite sensitive and needs to take a lot of pictures. With our system, we can study and characterize molecules that could speed up the MRI. As a result, a person wouldn't lie in the tunnel for an hour, but only a few seconds. However, this is only basic research, far from being applied. Rather, I am trying to push the boundaries of the method itself and make the findings available to other scientists.

How difficult is it to build a new spectrometer?

It is very challenging to process such a huge power, i.e. to get it into the sample and then into the detector, and not burn the detector and other components.  One has to think about other components of the spectrometer such as the modulation coil, polarizers, isolators, sample holder, or just the optical window isolating the cryostat from the rest of the spectrometer. Some components are exposed to temperatures below -270 °C, and most components are in a high magnetic field. So the choice of the right material has to be considered. It's quite a lot. In addition, the components are bonded to each other. All it takes is for one of them to malfunction and the whole thing "falls apart". Because of this, we try to support everything by creating simulations of the problem in order to detect it early.

How much does such a spectrometer cost?

Millions of dollars. 

And how do you manage to work with the possibility of breaking such expensive things? 

I used to be pretty worried about that. But a colleague in France once told me that the experience of a scientist is measured in euros (laughs). You have to be very careful and focused, but you also have to expect that things will break. You have to get used to that. You just can't do science without that. In science, it's expected. Even my design, which I've been working on for months now, may not actually work, although of course we have a design backed up by calculations, simulations and experience. And then we may have to redo some parts. But I'm not giving up. I think everything always works out in the end.

Read More

News Interviews and Views Research Alumni

Thanks to my studies at CEITEC, I can change rigid systems, says Lukáš Flajšman…

25. 5. 2022

News Research Interviews and Views Alumni

During my studies at CEITEC I was a “yes-woman”, I used every opportunity.…

18. 7. 2022