Simulation of energy distribution of signal electrons detected by the segmental ionization detector in high pressure conditions of ESEM

0431338 - ÚPT 2015 CZ eng A - Abstrakt
Neděla, Vilém - Konvalina, Ivo - Oral, Martin
Simulation of energy distribution of signal electrons detected by the segmental ionization detector in high pressure conditions of ESEM.
9th International Conference on Charged Particle Optics. Book of Abstracts. Brno: Institute of Scientific Instruments AS CR, v. v. i, 2014. s. 97. ISBN 978-80-87441-11-4.
[International Conference on Charged Parrticle Optics /9./. 31.08.2014-05.09.2014, Brno]
Grant CEP: GA ČR(CZ) GA14-22777S
Institucionální podpora: RVO:68081731
Klíčová slova: ESEM * detection system * EOD * Geant
Kód oboru RIV: JA - Elektronika a optoelektronika, elektrotechnika

Environmental scanning electron microscopy is indispensable in many experimental uses, including dry and electrically non-conductive samples, even though they can also be observed without charging artefacts with the low energy scanning electron microscope.Apart from the compensation of negative charge by positive ions from electron-gas interactions, ESEM allows for fully hydrated,mostly biological samples at a high pressure, semiliquid or liquid samples as well as sample changes and reactions during dynamical in-situ experiments. A negative aspect of ESEM is the reduction of the useful signal from the sample due to a lower number of non-scattered beam electrons. Therefore, the demands for detection system efficiency are higher, which calls for optimizations and the development of new detectors. This paper is focused on studying detection efficiency under various conditions, detector configurations and types of detected electrons. It is based on simulation of signal electron trajectories in vacuum and gas environment in a specially designed ionization detector of secondary electrons equipped with two circular electrodes. The goal is a better understanding of the relation between changes in detection electrode configuration and the type of the detected information. The EOD program extended with our Monte Carlo module for electron-gas interactions and signal amplification is used to simulate trajectories of signal electrons at emitted at selected energies from a realistic sample model. That is followed by an analysis of energies of the detected electrons by detection electrodes. The paper presents computed dependencies of energy distributions of the detected electrons on the water vapor pressure in the ESEM AQUASEM II. The simulated results are verified by experimental measurements. Our results provide practical conclusions, such as a possibility to record the topographical or material contrasts for selected configurations of our segmented ionization detector for ESEM.
Trvalý link: http://hdl.handle.net/11104/0236399