Carbon support films

Figure C2.17.1. Transmission electron micrograph of a Ti02 (anatase) nanocrystal. The mottled and unstmctured background is an amorjihous carbon support film. The nanocrystal is centred in die middle of die image. This microscopy allows for die direct imaging of die crystal stmcture, as well as the overall nanocrystal shape. This titania nanocrystal was syndiesized using die nonhydrolytic niediod outlined in [79].

Citrus pectin ( Polygalacturonic Acid Methyl Ester from Citrus Fruits, Grade I ) was obtained from the Sigma Chemical Company. It had a galacturonic acid content of 89% and a degree of esterification of 57. Separate aqueous solutions of citrus pectin were freeze-dried and air-dried in deionized water. These samples were replicated with 9.8A Pt/C and backed with 148A of carbon. The replicas for these samples were picked up without a carbon support film (38). 

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... 

Figure 14. Co nanoparticle rings and chains (a) low magnification bright-field image of self-assembled Co nanoparticle rings and chains deposited onto an amorphous carbon support film, where each Co particle has a diameter of between 20 and 30 ran, (b) and (c) magnetic phase contours (128 X amplification 0.049 radian spacing), formed from the magnetic contribution to the measured phase shift, in two different nanoparticle rings. The outlines of the nanoparticles are marked in white, while the arrows indicate direction of the measured magnetic induction [19].

Microanalysis Specimens for microanalysis were prepared by dispersing the powder ultrasonically in ethanol, placing a drop of this suspension on a thin carbon support film, and allowing the solvent to evaporate. X-ray absorption effects are negligible for particles on the order of O.lum thick allowing analysis of these particles without absorption corrections. For... 

The details of the structural characteristics of individual constituents in the various carbon deposits were obtained by examination of a number of specimens from each experiment in a JEOL 100 CX transmission electron microscope that was fitted with a high resolution pole piece, capable of 0.18 nm lattice resolution. Suitable transmission specimens were prepared by applying a drop of an ultrasonic dispersion of the deposit in iso-butanol to a carbon support film. In many cases the solid carbon product was found to consist entirely of filamentous structures. Variations in the width of the filaments as a function of both catalyst composition and growth conditions were determined from the measurements of over 300 such structures in each specimen. In certain samples evidence was found for the existence of another type of ca naceous solid, a shell-like deposit in which metal particles appeared to be encapsulated by graphitic platelet structures. Selected area electron diffraction studies were performed to ascertain the overall crystalline order of the carbon filaments and the shell-like materials produced from the various catalyst systems. 

PPO repeating units self-assemble into a supramolecular honeycomb-like layered structure, in which perforations are filled by coil segments. When cast from dilute CHCR solution onto a carbon support film, honeycomb-like supramolecular structure was observed, as revealed by transmission electron microscopy (TEM), in which coil perforations are packed on a hexagonal symmetry with distances between perforations of approximately 10 nm (Figure 14a). 

The adherence of small particles of precious metals to the surface of the support can be assessed by transmission electron microscopy. It has been observed that mild ultrasonic treatment of the catalyst in a liquid, such as ethanol, can remove precious metal particles from the surface of the support. After applying a drop of the suspension resulting from the ultrasonic treatment on the carbon films used as specimen support the precious metal particles released from the support show up on the carbon support film. Especially dark-field techniques are useful to indicate the presence of precious metal particles on the carbon support film. 

Figure 6.21 Vitreous Ice Freezing Device A thin (60-200 nm) carbon support film perforated with holes is placed on a standard EM carbon grid and then a sample of biological macromolecule is applied and rapidly frozen in liquid ethane (<138 K). After this, the vitrified sample is transferred into a cryoholder (under liquid nitrogen conditions) and then transferred to the microscope for visualisation. The holes in the thin film allow for the formation of monolayers of biological macromolecules in a range of orientations embedded within a thin (20-60 pm) layer of vitreous ice. The visualisation of such monolayer regions gives the best possible cryo-EM images of the embedded biological macromolecules.

The carbon support films used in the previous studies were similar, if not identical to LTI carbon (36), a material well tolerated by the circulation and used to coat prosthetic heart valves. These carbon substrates were replaced with other materials in... 

The lattice of a real two-dimensional crystal is never perfect, partly because of physical distortions of the two-dimensional crystals on the carbon support film and, to a lesser extent, because of electron optical distortions introduced by the electron microscope. Both types of distortion cause loss of high-resolution detail if different parts of the image are averaged when its Fourier transform is calculated. The distortions can however be detected by cross-correlation of the image with a small reference area in its centre. Once the distortions are known they can be corrected by re-interpolation of the original digitized image. 

The removal of direct carbon replicas is dependent upon the polymer. Boiling xylene vapor was used to remove drawn PE from replicas [296] in work on drawn polymer morphology. Hobbs and Pratt [297] described a direct carbon replica method for replication of a PBT impact fracture surface by evaporation of platinum at 20° and PBT removal in hexafluor-oisopropanol (HFIP). Latex film coalescence in poly(vinyl acrylate) homopolymer and vinyl acrylic copolymer latexes was studied using direct replicas [298]. As the latex films have a low glass transition temperature, they were cooled by liquid nitrogen to about -150°C in the vacuum evaporator and shadowed with Pt/ Pd at 45° followed by deposition of a carbon support film at 90° to the specimen surface. The latex films were dissolved in methyl acetate/ methanol. TEM micrographs of the latex films show the difference between films aged for various times (Section 5.5.2). 

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

PE single crystals grown from a very dilute solution on carbon supporting film individual lamellae of the same thickness grown one atop the other ... 

A technique which we have found effective is to use carbon supporting films on 200 mesh nickel grids. These were rendered hydrophilic (for these aqueous latexes) by ultraviolet radiation (Hanovia, Type 30620, 140 watt lamp) in air for 15 minutes. 

Polydiacetylenes are particularly convenient for studying polymers in the electron microscope. This is because thin monomer crystals can be produced by allowing a droplet of dilute monomer solution to evaporate on a carbon support film on an electron microscope grid [161. The monomer can then be polymerized by heating or even by exposure to the electron beam In the microscope. 

Fig. 2a-c. High resolution axial bright field transmission electron micrograph taken near Sherzer focus, for which the point-to-point resolution is = 2.5 A. The sam e consists of dispersed CdS crystallites on a thin carbon support film a an area containing several crystallites and demonstrating the size variational b, c magnified images of individual crystallites [7]... 

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