For TEMs with side-entry specimen stages, heating, cooling, straining the specimen, and chemical growth of materials can usually be done at the expenses of resolution and specimen tilt. For instance, we can have direct access to electrically heating the specimen and transfer of gases and liquids via a rod.

In-situ TEM/STEM experiments at atomic spatial resolution level have become available because of the developments of the instrument and holder designs. These in-situ synthesis and characterization are performed during gas-solid, liquid-solid, or liquid-liquid interactions, electron beam radiation, electrical, mechanical and thermal stressing, or chemical reaction with a typical time resolution of 1/60th of a second. Depending on the type of in-situ investigations, they normally need specially designed TEM/STEM holders as discussed on page3284.

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 (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]

Comparing with conventional TEM/STEM, environmental TEM/STEM has advantages as follows:
        i) Can avoid artifacts from sample preparations.
        ii) Can work on samples that contain water.

For TEMs with top-entry stages, it is more difficult and expensive to design and to rotate, heat, cool, or strain the specimen.

Television (TV) camera for EMs is used to observe and/or record electron microscope (EM) images for computer input, in situ observation, and multi-user observation. The TV observation is performed by a TV camera in combination with a dedicated fluorescent screen. In this case, the EM image is converted to a light image by the fluorescent screen.

[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).