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Cathodoluminescence spectra measurement
Schauer, Petr ; Autrata, Rudolf
In our laboratory the equipment for the investigation of cathodoluminescent (CL) properties of solid specimens has been built. The equipment is based on the completely rebuilt Tesla BS242 electron microscope, supplied by the light collection UV transmitting system, and by a fast and efficient photomultiplier tube (PMT) as the detection unit. The CL properties of specimens (slim disks) can be measured in continuous or pulse modes. So, in addition to the efficiency and decay times the emission spectra can be measured for 10 keV electron beams.
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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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Trajektorie signálních elektronů v nízkonapěťovém BSE detektoru
Wandrol, Petr ; Autrata, Rudolf
Nowadays the development of the image formation in scanning electron microscope (SEM) is oriented to the use of scanning electron microscopes with low accelerating voltage of the primary beam (LV SEM). Secondary electrons (SEs) for topographical contrast observation and backscattered electrons (BSEs) for material contrast observation are the main components of the detected signal in LV SEM. While the secondary electrons can be detected either by Everhart-Thornley scintillation detector or by the "in lens" SE detector, the detection of backscattered electrons (BSEs) in LV SEM is an unsolved problem yet
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Detekce signálu použitím segmantového ionizačního detektoru
Jirák, Josef ; Černoch, P. ; Autrata, Rudolf
For signal electrons detection at environmental conditions, it is often used a detector that utilizes impact ionization in the gaseous environment of a specimen chamber for a signal amplification. An electrostatic field created in a space between a grounded specimen and a detector electrode provides the energy needed for efficient ionization of secondary electrons. A voltage of several hundred volts is attached to the detector electrode. It was proposed an electrode system of a ionization detector, with several concentric electrodes divided into two halves - right and left. It was shown that the higher diameter of the electrodes brings an increased contribution of backscattered electrons to the detected signal. Different contrast mechanisms were studied
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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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