Holey carbon

The TEM images of selected samples were obtained on a JOEL 2000SX instrument operating at 160 kV. Powder sample, ca. 10 mg was sonicated 1 min with 5 ml of ethanol and a drop of this solution was put on 400 mesh Cu grids covered with a carbon holey film. 

Figure 3 Bright-field (a) and dark-field (b) STEM images of crushed ceramic particles dispersed on a "holey" carbon film supported on an electron microscope grid (shown at the right).

The samples were examined before and after catalysis by SEM (Phihps XL 20) and HREM by both a JEOL 200 CX operating at 200 kV and a JEOL 4000 EX operating at 400 kV. The specimens for TEM were either directly glued on copper grids or dispersed in acetone by ultrasound, then dropped on the holey carbon grids. 

In order to facilitate the mixing of CNTs and the nitrate, they were crushed ensemble in a mortar. The mixture was then heated within a Pyrex crucible in furnace up to 230°C for a period of 1 h. Subsequently, the sample was crushed to a fine powder in the mortar and disposed on a holey carbon grid. TEM... 

High Resolution Transmission Electron Microscopy (HRTEM, Philips CM20, 200 kV) was applied to get structural and nanotextural information on the fibers, by imaging the profile of the aromatic carbon layers in the 002-lattice fringe mode. A carbon fiber coated with pyrolytic carbon was incorporated in epoxy resin and a transverse section obtained by ultramicrotomy was deposited on a holey carbon film. An in-house made image analysis procedure was used to get quantitative data on the composite. 

Minireview. Genome Biology 2 1018.1-1018.5 Harris JR, Scheffler D (2002) routine preparation of air-dried negatively stained and unstained specimens on holey carbon support films A review of applications. Micron 33 461-480... 

HRTEM images were obtained on a Jeol JEM2010 ultra high-resolution analytical electron microscope equipped with an emission cathode operated at 200KV in bright field mode. The samples were examined with a magnification of 400,000. The ex situ treated samples were supported holey carbon coated copper grids for the experiment. 

Figure 7.9. (a) A comparison of TEM grid mesh sizes (b) Illustration of the float off method to prepare carbon-coated TEM grids (c) Comparison of a lacey carbon coating with holey carbon films deposited onto TEM grids. 

Specimen preparation. Most HRTEM investigations have used specimens in the form of crushed fracture fragments supported on a holey carbon film attached to a standard copper grid. Specimens thinned by ion (or atom) bombardment are also used, but the amorphous film which tends to form on the surfaces of foils prepared in this way is sometimes too thick for successful high-resolution imaging. See also Section 2.7. 

Figure 7.6 Images of a holey carbon film supported on a copper grid (same area).

Schmidt (45) reported a high-resolution electron micrograph of AU55-(PPh3)i2Cl6 on holey carbon films in proving that the AU55 cluster has a... 

The procedure for preparing holey carbon films (carbon film containing small holes of 100 nm diam.) is somewhat more complex. In this case the microscope slide is initially dipped into a 0.25% solution of formvar in ethylene dichloride and then held over a source of water vapor for sufficient time for an array of droplets to collect on the formvar surface. Excess formvar is drained off the slide and allowed to dry. During this stage the water droplets evaporate leaving behind a wide size range of bubbles in the formvar film. Carbon is evaporated onto this surface following the procedure described above so that the eventual result is the formation of a holey carbon film. 

The inset shows a TEM image of a similar pattern on a holey carbon copper grid, the dotted line bounds the area sought to be filed. The scale bar in the inset corresponds to 50 nm. 

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