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National Repository of Grey Literature 129 records found  beginprevious128 - 129  jump to record: Search took 0.05 seconds. 
Detection of signal electrons at higher pressure in the specimen chamber
 Jirák, Josef ; Autrata, Rudolf ; Špinka, Jiří
The advantages of the scanning electron microscopy working at higher pressures in the specimen chamber are connected with the possibility of observation of specimens structures, which are difficultly observable without previous preparation for microscopes working with pressures in the specimen chamber under 10.sup.-2./sup. Pa. The pressure in the specimen chamber up to approx. 2000 Pa brings the possibility of observation of specimens, which release gases, specimens containing liquid phase, including wet biological preparations, reactions on the phase interfaces, etc. At higher pressures in the specimen chamber it is also not necessary - due to neutralisation of the surface negative charge by gas ions - to coat electrically non-conductive specimens by a conductive layer.
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Sběrová účinnost detektoru sekundárních elektronů v REM
 Konvalina, Ivo ; Müllerová, Ilona
In order to collect the secondary electrons (SE), scanning electron microscopes (SEM) are equipped with the Everhart-Thornley (ET) type detector. The electrostatic field of the front grid, biased to a positive potential of several hundred volts , is to attract all SE of kinetic energy below 50 eV or at least those from the SE spectrum peak at 1(3 eV. However, the detection quantum efficiency (DQE) of such detectors has been found to be significantly lower than one, which is mainly given by their low collection efficiency. The electrostatic field of the grid cannot sufficiently penetrate toward the specimen and influence the trajectories of SE owing to grounded electrodes surrounding the specimen (specimen alone and its holder, specimen stage, pole piece of the objective lens, etc)
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National Repository of Grey Literature : 129 records found   beginprevious128 - 129  jump to record:
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