DUBNICKÁ MIDLÍKOVÁ, J. Návrh propojení far-infrared spektrometru k supravodivému magnetu a magneto-optické měření ve far-infrared oblasti [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. 2018.

Posudek vedoucího

Neugebauer, Petr

Jana Midlikova se zhostila své diplomové práce, zabývající se propojení infračerveného (IR) spektrometru se silným magnetickým polem, velice odpovědně. Práce je napsaná v angličtině a obsahuje šest kapitol. Po krátkém úvodu do problematiky Jana Midlíková představí obor molekulárního magnetismu, kde věcně popisuje charakteristické vlastnosti molekulárních magnetů, jejích typickou chemickou skladbu, metody jejich charakterizace pomocí spektroskopie za silných magnetických polích s důrazem na elektronovou paramagnetickou rezonanci. Následuje kapitola určená rešerši IR spektroskopie zabývající se samotnou IR technologií a řešením propojení IR spektrometru s magnetickým polem ve světě. Tyhle dvě kapitoly slouží jako teoretický základ její práce. V kapitole určené samotnému řešení návrhu propojení komerčního IR spektrometru se silným magnetickým polem se autorka zabývá komplexním řešením daného problému a jeho realizací. V kapitole se zabývá dvěma systémy: jedním pro univerzitu ve Stuttgartu a druhým systémem pro CEITEC VUT. První systém byl na základě vypracovaných podkladů (transportní stůl, optické řešení přivedení IR záření na vzorek a jeho následná detekce) Jany Midlíkové kompletně složen a jí samotnou otestován. Druhá verze určená pro CEITEC VUT bude teprve na základě jejích podkladů vyhotovena. Během diplomové práce pracovala samostatně, cílevědomě využívala veškeré zázemí a znalosti starších kolegů pro dosažení co nejlepších výsledků. Svou pílí navrhla, následně sestrojila a otestovala prototyp, který do budoucna přinese nespočet vědeckých výsledků. Jako vedoucí její diplomové práce jsem s prací Jany Midlíkové velmi spokojen a navrhuji její práci k obhajobě.

Posudek oponenta

Slageren, Joris van

The Master Thesis presented by Ms Bc. Jana Midlíková deals with the design and implementation of setup to couple an existing FTIR spectrometer to an existing 15 Tesla superconducting solenoid magnet, as well as preliminary measurements with the successfully developed setup. The aim of the work is to allow the investigation of magnetic materials with excitations in the far-infrared region of the electromagnetic spectrum (wavenumber between 10 and 400 cm–1) in the presence of a magnetic field. Specifically, she studies paramagnetic molecules with large magnetic anisotropies in the form of zero-field splittings. Such systems are known as single molecule magnets and they have been proposed as novel materials for magnetic data storage applications. The first step in the Master Thesis work was the design of the optics coupling FTIR spectrometer to the solenoid magnet. Design aspects that Ms Midlíková took into account during this process included the elimination of magnetic materials, preventing the use of windows and the suitability of the materials used for the magnet insert for low-temperature operation. In addition, she designed a movable table for the spectrometer that allows use of the FTIR spectrometer in different experiments, and which allows to move the spectrometer in close proximity to the magnet. To couple radiation out of the spectrometer, she opted to adapt the reflection unit. This turned out perhaps not to be the wisest choice, since the beam exiting the reflection unit is focused rather than collimated, which complicated the guidance of the beam into the magnet insert. In addition, a very heavy valve with a wide opening was selected for isolating the spectrometer from the insert during sample change. Here more sensible options, such as positioning directly on the sample rod would have been available, where the beam diameter is much narrower. In her second design, she demonstrates that she is able to exploit the lessons learned and uses a conventional exit port, as well as a differently placed isolation valve in her design instead. In this second design, she also solves the problem of moving the sample into and out of the beam, so as to allow measurements with and without sample allowing the recording of proper transmission spectra. Finally, Ms Midlíková briefly characterizes the setup and presents first successful measurements using cobalt complexes obtained from collaboration partners. Overall, the work presented in the Thesis fulfils the requirements of the assignment given to Ms Midlíková to the fullest extent. She has successfully designed the setup for coupling the spectrometer to the magnet, overseen its construction, performed tests and carried out first real measurements on novel samples. In addition, she has managed to design a second setup which improves on the original design. Importantly, this demonstrates her abilities to exploit the results achieved and use these to her advantage. The approach that she has chosen was entirely suitable. Certain issues that were later revealed could perhaps have been foreseen. In addition, an alignment unit featuring two mirrors instead of one may prevent the 70% radiation coupling losses, due to better alignment capabilities. A number of similar setups exist around the world, and she describes these in detail in her Thesis. In that sense her work does not lead her along completely untrodden paths. Her setup is different in that it uses a solenoid magnet rather than an optical cryomagnet with windows. This has the advantage that fewer windows are required, but leads to longer radiation path lengths. Her setup differs from the Grenoble spectrometer in that the detector is not inside the magnet, allowing variable temperature measurements. After the improvements proposed by Ms Midlíková, the setup will be likely ready to be used and applied to real and novel research samples. The Thesis is well structured. In the introduction Ms Midlíková demonstrates that she has rapidly gained a thorough understanding of the physics behind the studied materials, as well as of the experimental techniques to study these systems. The introduction is at times concise, at times perhaps too exhaustive as in the description of signal-to-noise ratios. Overall, the Thesis is written in very readable English, with very few typographical errors, but occasionally marred by colloquialisms and uncertain use of articles. Graphics are mostly kept simple, but functional. Literature citations are to the point and adequate.

eVSKP id 109732