Electron microscopy
 
Vacuum Sealed Electron Transparent Windows for In-Situ TEM
- Practical Electron Microscopy and Database -
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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
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For the in-situ TEM experiments based on gas-solid or gas-liquid interactions, the gas or liquid needs to be confined to the sample area in order to protect the column vacuum of TEM. The modified part, used to confine the gas or liquid, is known as environmental cell (E-cell), which can be achieved mainly by two methods:
          i) Vacuum sealed electron transparent windows above and below the sample are used as shown in Figure 3276 (also see Liquid/gas TEM and STEM Stage and Holder). This method can be obtained by specially designed TEM/STEM holder.
          ii) A combination of small apertures and extra pumps are used in the TEM column. This system is also known as differential pumping system. [1-4]

Figure 3276 shows the schematic illustration of window technique with a pair of electron transparent windows that are placed above and below the TEM sample. In this system, the sample and its surrounding gas/liquid are completely sealed off from the TEM column so that the pressure/vacuum of the TEM stays constant. However, sufficiently strong (e.g. thick) window/film is needed to resist the pressure difference between the cell and TEM column. The disadvantages of this system are:
        i) The resolution and contrast of images can potentially be degraded.
        ii) A risk is that the windows can be damaged, and then the TEM column will be destroyed or even the chemical gas/liquid will attack the microscope.

Even thought the disadvantages above exist, this method is still the only choice for liquid environment and liquid chemical interaction research.

schematic illustration of window technique with a pair of electron transparent windows

Figure 3276. Schematic illustration of window technique.

 

 

 

 

 

[1] P. Butler and K. Hale, In Situ Gas-Solid Reactions, Practical Methods in Electron Microscopy, Experimental Microscopy (North Holland Co., 1981), pp. 239 and 309.
[2] R. Sharma and P. A. Crozier, Transmission Electron Microscopy for nanotechnology N. Y. Z. L. Wang (ed.) (Springer-Verlag and Tsinghua University Press, 2005), pp. 531–565.
[3] L. Marton, Nature 133, 911 (1935).
[4] T. L. L. Daulton, B. J. Lowe, and J. Jones-Meehan, Microscopy and Microanalysis 7, 470 (2001).

 

 

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