Abstrakt
A possibility to study biological samples in their native state, or even living organisms, using an environmental scanning electron microscope (ESEM) is of great importance for biologists. Sputter-free, electrically non-conductive and wet biological samples in their living and native state are observed using ESEM under conditions of high pressure water vapors that ranges from units to thousands of Pa in the ESEM specimen chamber.
One of unwanted consequences of the electron beam-gas interaction is the electrons scattering that results in beam spot defocusing followed by the decrease of the detected signal-to-noise ratio. This can be compensated by the reduction of beam electrons gas path length and scanning speed or by the increasing of the beam energy [1].
The latter two parameters fundamentally enhance radiation damage of sensitive and soft native samples and represent a limiting factor for their observation using ESEM. This problem can be overcome by the use of special methods like Low Temperature Method for the ESEM (LTM) [2], ideally in a combination with advanced low noise detectors with very high detection efficiencies.