The team, which works at the joint laboratory of ISI and the Institute of Electrotechnology of TU Brno, is focused on the problems of scanning electron microscopy whose main feature is a relatively high pressure of gases in the microscope specimen chamber. There are studied such kinds of problems as physical processes of interaction mechanisms at collisions of electrons with gas molecules, ways of electron scatter in gaseous media, differential evacuation of a microscope, problems of electron scatter in the dependence on the gas medium pressure, etc. Special attention is paid to the ways of detection of signal electrons and ions. Scintillation methods using single crystal materials, ionisation methods and the combined use of both methods are investigated. Problems of suppression of the electrons carrying the undesirable signal, problems of the attainment of the maximum signal output, problems of cooling a specimen and long term preservation of its wetness in the space of the specimen chamber, etc., are dealt with. Extraordinary attention is concentrated on the investigation of wet biological specimens in their natural state. The team is concerned with the investigation of new scintillation materials based on single crystals of dioxides and with their use in detection systems of signal electrons, particularly in scanning electron microscopes. Special attention is paid to the computer simulation of interaction mechanisms between electrons and a solid, to light propagation in light guides, and electron propagation in electrostatic and magnetic fields. Simulation results are compared with the experiment directed at the design of systems for the detection of backscattered and secondary electrons. The team is concentrated on the development of methods of detection of electrons that are difficult to be detected, such as low energy backscattered electrons or electrons propagated in a gas medium. Different modes of information obtained by means of electrons with different take-off angles and energies propagated in different media are studied. The basic methodological conception is connected with the detection systems that ensure attainment of a high resolution image of the studied specimen, enable separation of different types of detected electrons and cathodoluminescent light, record different contrast mechanisms, and make use of the variety of the physical properties of signal electrons in scanning or transmission electron microscopy. The team is concentrated on the study of electron interaction in solids, cathodoluminescence, and on the research of noise effects. The team activity includes the Monte Carlo simulation of interaction processes and related optical effects. The results are used for the construction of detection systems and/or screens for electron microscopes. The essence of the current project is the investigation of properties of single crystal imaging screens (cerium activated single crystals of yttrium aluminium garnet YAG:Ce), and their exploitation in transmission electron microscopy. The project is motivated by the effort to put into practice new imaging components with relatively small dimensions and a high spatial resolution that will enable gaining of high quality digital images of objects investigated in the transmission electron microscope. The goal of the project is to experimentally determine the spatial resolution and the detection efficiency of a single crystal cathodoluminescence screen in the dependence on its thickness. The results of the measurement are compared with the values predicted by the theory and obtained by a computer simulation. The results are used for the design and construction of an imaging unit of the transmission electron microscope.
The study of the electrons´ interactions in solids is focused on the cathodoluminescence and especially to its employment in the detectors of electrons, screens for electron microscopes and other imaging elements in the area of scientific instruments.
The research and development of scintillators have led into the introduction of scintillation detectors of new generation, which are nowadays commonly employed in scanning electron microscopes and are a significant export article of Czech industry.
The modelling of electron interactions and related optical phenomena in solids is based on the Monte Carlo methods and is focused on obtaining of difficultly measurable information of configuration of processes in the volume of the materials examined by means of electron.
The computer-optimised design of materials and geometry of scintillation system for the detection of electrons serves not only for obtaining of the base for construction of very effective detection systems but also for introducing of theoretical basis in this research area.
The research of the fluctuation processes in the elements for the electrons´ detection is focused on the phenomena related to the collection of electrons, with luminescence and transport of photons. The results of this study are applied at assessment of the detection quantum effectiveness (DQE) of scintillation detectors of electrons.
Environmental scanning electron microscopy of wet specimens and specimens with non-conductive surface – interaction mechanisms which are in motion at collision of electrons with gas molecules in the specimen chamber of the microscope – ways of electron diffusion and dispersion of electrons in gaseous environment and at dependence on gas pressure – detection of signal electrons and ions at pressure of gases in the range of 1 Pa – 1 kPa – ionization and scintillation detection systems.
Detection mechanisms in scanning and transmission electron microscopy – research of new single crystal scintillation materials – propagation of photons in scintillators and light guides – influence of magnetic and electrostatic fields on trajectories of signal electrons – detection of low energy backscattered electrons – study of contrast imaging and influence of share of secondary and backscattered electrons on forming of contrast - angular and energy configuration of backscattered electrons – possibilities of separation of secondary and backscattered electrons – influence of effectiveness of detection systems to image resolution.
Research of battery masses by the ESEM method (FEKT-VUT Brno). Research of histological and embryologic materials (ÚHE-MU Brno) – structural influence of treatment of enamel on the quality of teeth prostheses (IDVPZ – Brno), research and working out of special methods for observation of wet biological specimens.
