Advantages include high stability in the electron beam and high resolution examination of the adsorbed specimen. Disadvantages include a hydrophobic surface which is not of uniform thickness. Carbon films For this technique, carbon film is evaporated onto a freshly cleaved mica surface and the sample is applied to the surface of the carbon film attached to the mica. The carbon films can be stored on the mica for long periods without them becoming contaminated, the films are thin but tough so can be easily examined in the TEM without any noticable specimen movement. However, they are fragile and must be manipulated with care.
Hexagonal grids seem to offer a more stable support.
Return to top of page Making the carbon film Take a piece of mica and cut off a square or rectangular piece that is approximately 2 x 3 cm. Cleave the mica with a razor blade or scalpel that has been cleaned with acetone. Once the mica has begun to separate along a cleavage plane, forceps may be used to pull the mica completely apart. It is better to do this than to scratch the surface of the mica with the razor blade. Mica, as purchased from most EM supply companies, is rather thick and a new piece may be split around 4 times.