Coatings for TEM

Carbon films are used as specimen supports, for replicas and as coatings for ultrathin sections. Carbon evaporation is difficult to perform as a 

Platinum is the most difficult metal to evaporate, but it provides the finest grained shadow. Chromium is quite coarse and useful for very low magnification studies. Aluminium is used for optical microscopy. 

Carbon support films are evaporated directly onto freshly cleaved mica, NaCl, plastic coated grids or plastic coatings on glass slides. There is 

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Innocent surfaces do not allow formation of such extended 2D areas as has been demonstrated by using carbon coated copper grids (for TEM) or liquid surfaces as used for Langmuir-Blodgett techniques. Only islands... 

TEM Studies. Electron micrographs were obtained on JE0L, TEMSCAN --100 CX11 combined electron microscope and a HITACHI H1M1B (TEM) operated at 2 x 10 magnification. The specimens for TEM were obtained by placing a drop of the colloid solution on a copper grid coated by a carbon film. 

So far, we have prepared and tested many kinds of colloids, mainly in nonaqueous suspensions with combinations of metals or alloys as a dispersed phase and organic liquids as the dispersion media, without the use of any dispersing agents these are listed in Table 9.4.1. We next give some examples of transmission electron micrographs of nanoparticles produced by an aerosol method. A sample for TEM measurement was obtained by dropping colloidal suspension onto a Cu mesh coated with an evaporated carbon film of 10 nm thickness. Many colloids were so unstable... 

Since one of the issues raised in this paper is whether the objects seen in the TEM images are a proper representation of the structures present in solution, we will describe briefly sample preparation strategies. For solutions of micelles in hexane, a very volatile solvent, samples for TEM studies could be obtained by aspirating a dilute solution directly onto a carbon-coated copper grid. Most of the solvent likely evaporated as the sample was deposited on the substrate. Alternatively, the TEM substrate could be dipped briefly into a dilute solution of the micelles and allowed to dry. This method also worked for less volatile solvents like decane. For decane, we could also place a small drop (a few pi) of solution on the grid and then touch the edge of the droplet with a Kimwipe to remove excess solvent. For several samples these methods were compared, and we observed the same morphology. 

The brominated sticks are embedded in Spurr epoxy resin (Spurr 1969) and sectioned with a diamond knife or glass knife mounted on an ultramicrotome to give cross sections of 0.15//m thickness for TEM-EDXA or 0.5//m thickness for SEM-EDXA. The sections are then placed on a carbon-coated collodion film on the specimen support grid. The specimens are carbon-coated again to avoid charging. 

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