Single-Molecule Magnets with Trigonal Symmetry of the Coordination Polyhedron: Structure, Magnetic Properties and Deposition on Surfaces
Transition and inner-transition metal complexes possessing significant magnetic anisotropy often exhibit slow-relaxation of magnetization of a purely molecular origin and thus they behave as so called single-molecule magnets. The aim of this thesis is to investigate synthesis, structure and magnetic properties of coordination compounds of selected metal atoms (e.g. CoII, FeIII, DyIII) with tripodal ligands. Furthermore, the properties of hybrid systems prepared by deposition of selected compounds on surfaces (such as graphene, Au, transition metal dichalcogenides) will be performed. For more details please contact Petr Neugebauer.
Development of Fourier Transform InfraRed Spectroscopy in High Magnetic Fields
Fourier Transform Infra-Red (FTIR) spectroscopy in high magnetic fields presents an ideal combination of experimental techniques that can probe and elucidate properties of the most advanced materials. This technique provides complementary information to the commonly used measurements of transport, magnetization, and thermodynamic properties. The aim of this PhD project is to develop a compact spectrometer for FTIR spectroscopy in the high magnetic field at CEITEC BUT. The developed spectrometer will be used to perform sensitive measurements on Single Molecule Magnets (SMMs), modern 2D materials or combination of both.
THz Frequency Rapid Scan Electron Spin Resonance Spectroscopy
Dynamic Nuclear Polarization (DNP) is a phenomenon, that can enhance greatly the NMR sensitivity (several hundred times at least). There are several mechanisms of DNP, though all of them result from the transferring of electron spin polarization (from special polarizing agents) to nucleus. This process is strongly dependent on the electron spin relaxation of the polarizing agent. However, due to the instrument limitations, the spin dynamics of polarizing agents is studied very poorly at frequencies above 100 GHz, especially at frequencies of 263, 329 and 394 GHz, which correspond to NMR proton frequencies of 400, 500 and 600 MHz, respectively. Usually, the spin relaxation properties are studied using the pulsed method. Unfortunately, the nowadays level of microwave sources at THz frequencies, mostly in terms of output power, does not allow the implementation of the pulsed technique in the wide frequency range. For this reason, the Rapid Scan Electron Spin Resonance (RS-EPR) spectroscopy is the only possible technique for the investigation of spin dynamics at THz frequencies. In this project, PhD student will (i) develop and implement a technique of fast frequency sweeps into the high field/high frequency EPR spectrometer (ii) investigate the spin relaxation processes in different DNP polarizing agents in the wide frequency and temperature ranges.
Design of Multipurpose Sample Holder for THz Spectroscopy
The aim of this PhD project is to develop multipurpose non-resonant sample holder for broadband Electron Paramagnetic Resonance spectrometer based on THz rapid frequency scans (THz-FRaScan-EPR) as well as for Fourier Transform InfraRed (FTIR) studies. Thanks to the developed sample holder the THz-FRaScan-EPR spectrometer will allow multi-frequency relaxation studies of variety of samples ranging from oriented bulk (crystal) materials, over powdered samples to air sensitive samples and liquid solutions. Furthermore, the design should allow inserting samples from Ultra High Vacuum. The sample holder should primary operate at frequencies between 80 GHz to 1100 GHz, at temperatures from 1.8 K to 300 K and at magnetic field up to 16 T. The sample holder will be tested on variety of samples ranging from Single Molecule Magnets over modern 2D solid state materials to air sensitive biological samples.
Development of computational procedures and computer programs for processing pulsed EPR data
Pulsed Electron Paramagnetic Resonance (EPR) methods are intensively used to investigated structure and dynamics of complex macromolecules containing unpaired electrons. Among these methods Pulsed Electron-Electron Double Resonance (PELDOR) also known as Double Electron-Electron Resonance (DEER) has emerged as a powerful technique to determine relative orientation and distance between macromolecular structural units on nanometre scale. For successful applications of pulsed EPR methods it is important to have tools enabling transformation of measured signals into structural information. The goal of this PhD project is to develop new effective computational procedures and computer programs for the processing of measured pulsed EPR data in order to extract structural and dynamical information from experiments. This goal also includes application of the developed computational methods to real experimental data obtained on the molecules tagged with spin labels.
New generation of graphene bolometers
Since the discovery a few years ago that a single layer of graphite, graphene, could be mechanically exfoliated from larger crystals using scotch tape, there has been an upsurge of research on graphene and other materials with a layered crystallographic structure similar to graphene. The possibility to combine single-layer materials with different electronic properties into heterostructures with atomically sharp interfaces and the suitability for flexible substrates offer unprecedented opportunities for novel device architectures. The ideas can be realized thank to the progress in developing processes to grow large area, high quality, single-layer material since mechanical exfoliation is a slow process for research (although it provides high-quality layers) and it is indeed not suitable for commercial applications. Methods for large-area growth of graphene have been developed in the past few years and are now used by several groups. They include chemical vapor deposition (CVD) of graphene on copper or nickel foils and epitaxial synthesis via Si sublimation at the surface of SiC substrates. However, substantial area growth of monolayers of other layered materials is still a challenge, although methods to grow millimeter-size monolayer films of MoS2 by CVD have already been developed. Fabrication of high-quality large-area monolayers facilitates the systematic study of another particularly intriguing aspect of these materials, namely that the dimension of a monolayer can be further reduced from 2D to 1D or 0D by patterning it in the shape of nanoribbons or quantum dots. The realization of quantum confinement down to zero dimension indeed leads to exciting physics, and we will investigate if it can be used for practical applications. In this thesis, we will study how quantum confinement, achieved by nanopatterning these two-dimensional (2D) materials can yield novel high-performance devices.
If you are interested in one of these topics and you can prove it -
you can contact Group Leader personally
Dr. Petr Neugebauer
+420 734 513 280