| Solvers: Autrata Rudolf, Jirák Josef (VUT Brno), GA ČR GA102/05/0886, date: 01:01:2005 - 31:12:2007. Environmental scanning electron microscopy (ESEM) belongs to the last trends of microscopic methods. It enables working in the specimen chamber with pressures higher than in a standard SEM (approx. 103Pa in comparison with 10-3Pa) and observation of specimens in their natural wet state without previous preparation. A number of problems connected with this methodology has been solved, nevertheless, several imperfections are not finished yet. The project deals with one of them – detection of true secondary electrons using a way totally suppressing the influence of undesirable backscattered electrons. The principle of the detection is the exhaust of secondary electrons from the specimen placed in the environment of high pressure of gas to the environment of high vacuum, in which the scintillator with high electrode potential is placed. The secondary electrons are exhausted using the low electrostatic field to the space of two chambers with differentially pumped pressure of gas. These chambers are separated with apertures forming contemporarily electrostatic lenses. The focused electrons are accelerated in the vacuum chamber by the electrostatic field to the scintillator at origination of the signal. The second version of the detector uses a double space pumped immersion lens with the magnetic and electrostatic fields for transfer of secondary electrons from the specimen. |
