Interview with Dr. Jana Jurmanova, Supervisor of Electron Microscopes at the Department of Plasma Physics and Technology, Masaryk University
In modern academic labs, nanometer precision defines the standard for reliable results. Electron microscopy provides the resolution and stability researchers need to confirm the structure and performance of advanced materials. With advances in detectors, automation, and low-energy imaging modes, new possibilities are emerging across both academic and industrial research.
We discussed how electron microscopes are used in an academic environment and how the field of electron microscopy is evolving from an operator's perspective, with Dr. Jana Jurmanova, supervisor of electron microscopes at the Department of Plasma Physics and Technology at Masaryk University in Brno. This year, the laboratory expanded its instrument portfolio: alongside its Tescan MIRA 3, it has newly installed a Tescan CLARA.
Investigating Thin Films from Graphene Onwards
What are the main research areas in which your institute uses an electron microscope?
We are part of CEPLANT, a large research infrastructure focused on plasma technologies. Our work combines fundamental research - understanding plasma physics and the mechanisms occurring in ionized environments - with the applications that follow from it. In practice, this means that our researchers deposit thin films using magnetron sputtering and then need to analyze their thickness, morphology, homogeneity, and chemical composition.
At this stage, the electron microscope is essential. It shows us what the layer actually looks like: whether the surface is smooth, cracked, island-like, or exhibits characteristic wrinkling. These visual details often reveal a great deal about the material's quality and usability.
Which details are most critical when evaluating new thin films?
Surface morphology is one aspect. Beautiful electron micrographs often show wrinkled or highly irregular layers; they are certainly photogenic, but from a materials-engineering perspective, they often highlight weaknesses. Ideally, a film should be flat, thin, flexible, and mechanically robust.
But surface observations are just the beginning. Using the electron microscope, we also examine fracture cross-sections to understand how the film "grew." This reveals the internal microstructure, which can be columnar, polycrystalline, or feature an amorphous, glass-like texture. A fracture cross-section essentially acts as an archive of the growth process: if the composition changed over time during deposition, the cross-section records these changes.
Is electron microscopy indispensable here primarily because of its resolving power?
Resolution is absolutely key. We can distinguish structures on the scale of tens of nanometers - capabilities that conventional methods such as optical microscopy simply cannot match. Techniques like AFM or STM do exist, but working with an electron microscope is significantly more practical and user-friendly.
Furthermore, with the Tescan CLARA, we can combine morphological information with elemental analysis. The integrated energy-dispersive spectroscopy (EDS) module allows us to determine elemental composition from characteristic X-ray emission. This combination of imaging and compositional information is invaluable in deciding on material quality and how to adjust deposition parameters. One example is titanium nitride coatings, where the ratio of individual elements strongly influences both appearance and functional performance.
MIRA and CLARA: A Decade of Tescan Innovation in Practice
You work with two different microscopes, Tescan MIRA and the newly acquired CLARA. How do you divide tasks between them?
We've had the MIRA 3 since late 2012, and it has proven to be a remarkably solid instrument. It's an exceptionally timeless series. Even after more than ten years of intensive use, MIRA still handles approximately 90% of the routine tasks we face. For control and analytical applications, it remains fully sufficient.
Over the past decade, demand for electron microscopy at our institute has grown significantly. Nearly all of our students encounter it during their studies. CLARA was therefore added as a complement rather than a replacement. While MIRA remains our reliable workhorse for routine applications, CLARA is dedicated to advanced research—particularly when working with non-conductive or ultrathin samples.
In my view, development in electron microscopy has slowed somewhat over the last decade, as manufacturers are approaching physical limits. Improving resolution by a fraction of a nanometer requires major innovations in electromagnetic optics, more sensitive detectors, and more sophisticated physical approaches. Yet Tescan has achieved it - CLARA represents a cutting-edge form of electron microscopy.
In what ways does CLARA represent a qualitative leap?
CLARA offers an elegant solution to a long-standing challenge for most microscopists: charging of non-conductive samples. When an electron beam irradiates a non-conductive material—such as hair, biological tissues, or polymers - electrical charge accumulates on the surface, causing image distortions.
The usual workaround is metal coating, but that's not always desirable, because we then observe the metal layer rather than the true surface. CLARA's strength lies in its ability to operate at low accelerating voltages and lower beam currents. It also supports "acquisition stacking": the microscope records a rapid series of low-exposure images, which are then aligned and merged computationally. The result is a sharp, accurate image without coating - showing the authentic surface. It's a brilliant solution.
Lower accelerating voltages and lower beam currents reduce the interaction volume, giving us more surface-specific information - crucial when studying topography or ultrathin films. At the same time, the risk of beam damage decreases, which is particularly important for biological and organic samples.
Low-energy operation also minimizes charging. Combined with automatic stigmation - where the microscope iteratively optimizes stigmator settings - CLARA often provides auto-stigmation that's as good as, or better than, manual correction. We appreciate this especially when training students and novice users.
Detectors in Action: Topography and Composition in One View
Which detectors does CLARA add beyond what you have on MIRA?
First, both microscopes have an SE detector, but CLARA's has higher sensitivity. Then there's the backscattered electron (BSE) detector: CLARA is equipped with an elegant four-segment design, where each quadrant collects signal from a different direction, mimicking side illumination. By summing or subtracting segments, we can tune the image between topographic contrast and Z-contrast, where heavier elements appear brighter.
We also have a six-position STEM detector, which enables transmission imaging of very thin samples - ideal for graphene flakes or ultrathin structures. It captures signals from multiple angles, allowing us to quickly assess the quality of prepared samples before imaging them in high-resolution TEM instruments. We can thus pre-screen samples using STEM, saving time and avoiding unnecessary use of advanced equipment.
And of course there's the new Oxford EDS system. It offers better energy resolution, higher sensitivity toward low-energy X-ray lines, improved peak separation, and a larger active area that speeds up spectrum acquisition. In comparative tests conducted in September, we found that we could achieve the same analytical results as with MIRA - but almost twice as fast.
Researching Materials of the Future: Nanoparticles and Graphene
You also work with advanced materials such as graphene and nanoparticles. What do you focus on in these areas?
We have two research groups dedicated to graphene. One focuses on fundamental research and synthesizes graphene from ethanol in a plasma discharge - producing thin carbon flakes (1–10 atomic layers) roughly 200 nm in size. The second group works with premade flakes about one micrometer across and creates thin or free-standing layers from them. The material is extremely light yet cohesive.
Here, CLARA's low-energy capabilities and STEM detector are significant advantages. We can image individual graphene flakes in detail, determine their dimensions, and pre-select suitable samples for further analysis with TEM.
And what about nanoparticles?
We study metallic and oxide nanoparticles used as catalysts or components of functional surface layers. The electron microscope allows us to observe their size, shape, and distribution. CLARA is ideal for this - its resolution allows us to distinguish individual particles on the scale of tens of nanometers, while EDS provides compositional information. Analyzing a single particle is challenging because of substrate background, but CLARA still makes this feasible.
Workflow: From Screening to Detail
How does the analytical workflow proceed when you receive a new sample?
We begin with basic screening. Using SE or BSE detectors, we examine morphology and quickly identify regions that may differ in composition. Then we acquire a rapid EDS spectrum to check for elemental presence. If needed, we record elemental maps to assess spatial distribution. For thin films or nanostructures, we switch to STEM mode to highlight local variations in density or composition.
Once we know what's interesting and worthy of deeper investigation, we perform detailed mapping. We define the region of interest, choose an appropriate resolution, set the dwell time for each pixel, and adjust the number of passes or acquisitions to improve the signal-to-noise ratio.
How long does it take to acquire a high-quality spectrum or map?
A typical publication-quality micrograph at 1200 × 1200 px takes roughly 30 seconds. For a very detailed image at 4000 × 4000 px, acquisition takes about 10–15 minutes. Spectra vary depending on the purpose: a quick check for elemental presence takes about one minute, while a high-quality, well-resolved spectrum takes around two minutes. Elemental maps require more time depending on the resolution we need.
Students and Knowledge Transfer
You mentioned students - how do you train new operators?
In addition to commercial collaborations, we run several research groups and train bachelor's students. They can encounter electron microscopy as early as their second or third year through introductory courses or activities like "Start with Science." At the master's level, instruction becomes more advanced, and students gain deeper knowledge. Doctoral candidates work almost independently; electron microscopy is assumed. We also have a dedicated Microscopy study program - a follow-up master's degree that requires a bachelor's degree in physics. Many students complete their theses in industry, which is mutually beneficial.
Choosing CLARA: Parameters and Decision-Making
When selecting a new microscope, you must have had clearly defined criteria. What were the priorities?
The top priority was stable low-energy operation. This was crucial because we frequently work with non-conductive and fragile samples. We wanted fine control of beam current and highly sensitive detectors. I also emphasized user flexibility - presets, user profiles, and features enabling consistent results across operators. Tescan has made tremendous progress in the user interface and automation. For example, the automatic astigmatism correction on CLARA is nearly flawless.
The purchase was, of course, part of a public tender, and the final parameters were decided by the grant provider—the Ministry of Education. We received a budget, compared the available systems, and I must say that Tescan CLARA won by a large margin. We weren't seeking absolute records in speed or resolution, but reliable performance for universal academic use. Practically, that means: an overview spectrum in around a minute, a detailed spectrum in about two minutes with a good signal, plus the ability to quickly balance speed and quality.
What's essential is that electron microscopy will remain central in materials research. The intuitive, fast, and accurate combination of morphology and elemental analysis is simply irreplaceable. CLARA gives us the flexibility and speed that science, industry, and universities increasingly require.
Thank you for the interview.