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Adaptation of scanning electron microscope to environmental scanning electron microscope
Neděla, Vilém
This paper deals with adaptation of the scanning electron microscope (SEM) to the environmental scanning electron microscope (ESEM). It focuses especially to the construction and assembly of the differential pumping chamber together with the detector board of the differential pumping chamber and it comments reasons of necessity of the assembly of these parts in the environmental scanning electron microscope.
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Dispersion and detection of signal electrons in environmental SEM
Romanovský, V. ; Neděla, Vilém ; Hutař, O.
The environmental scanning microscope is based on convenient adaptation of classical SEM employing the focused primary electron beam. For the proper function of the electron gun the pressure in this part of the microscopemust be less than 10.sup.-3./sup. Pa. The working pressure in the specimen chamber in environmental microscope reaches the order of hundreds of Pa.Therefore, the effective vacuum separation of these two parts is necessary. This can be obtained by the use of two or more apertures limiting the gas flow. It is also necessary to evacuate the space between the apertures by a vacuum pump of a high pumping speed. The increasing of pressure in the specimen chamber brings some difficulties, especially the dispersion of signal electrons by the influence of interaction with the gaseous environment.
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Influence of magnetic field upon detection in environmental SEM
Romanovský, Vladimír ; Neděla, Vilém
The single-pole magnetic lens has been constructed and placed co-axially with the beam of primary electrons below the specimen holder. A scheme of its configuration is shown in Figure 1. The lens had to be designed with consideration to the size of space available in the specimen chamber. The situation was complicated by the necessity of placing a magnet below the specimen holder. For this reason the height of 30 mm and diameter of 55 mm of the magnetic lens were chosen. The dependency of induction B on the current I through the magnet was measured by a T-meter.
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Optimalizace podmínek hydratace v ESEM
Autrata, Rudolf ; Neděla, Vilém
Study of biological specimens of soft tissues with fine and very fine hydrated structure still remains a big problem because this structure can be easily damaged by dehydration during the initiating phase of vacuum pumping of a microscope. The attention is thus focused on setting up the conditions for complete dehydration of samples, ensuring the nature state of a sample during the critical phase of pumping of a microscope
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Měření a nastavování vlhkosti v Environmnetálním rastrovacím elektronovém mikroskopu
Autrata, Rudolf ; Jirák, Josef ; Neděla, Vilém ; Špinka, J.
When we are detecting signal electrons with an ionization detector in ESEM, the most advantageous is to use, with respect to the effectiveness of ionization, environment of water vapours in the specimen chamber. The most suitable are saturated water vapours (relative humidity of 100%). This environment is also advantageous for observation of specimens containing water. At pumping of the specimen chamber to the working pressure (typically around 1000 Pa), in the case of wet specimens, evaporation of specimen can occur, or on the contrary, condensation of water on them. It means, that in some cases the specimen will not remain in the original state. That is why we try to adjust and optimize the pumping procedure and pumping of water vapors to minimize deformation of the observed specimens
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