Imaging in a differential pumped environmental TEM (ETEM) results in general in a degradation of the image quality. Scattering of electrons by gas molecules in the pressurized volume between the pole pieces blurs the image and decreases the signal-to-noise ratio of the acquired images. The somewhat simple picture of a plane wave interacting with the sample of interest is no longer valid. Furthermore, the exit wave from the sample is altered by scattering events taking place after the sample in the direction of propagation. In this chapter, the effect of the increased gas pressure between the pole pieces in an aberration-corrected highresolution transmission electron microscope is discussed in order to shine some light on the additional phenomena occurring in ETEM compared to conventional HRTEM. Both direct effects on the image quality and more indirect effects rising from gas ionization are discussed.
|Title of host publication||Controlled Atmosphere Transmission Electron Microscopy : Principles and Practice|
|Editors||Thomas Willum Hansen, Jakob Birkedal Wagner|
|Publication status||Published - 2016|