Transmission Electron Microscopy TEM Data

Interference Functions /(s) of Amorphous (as Deposited) Carbon Films Compared to Graphite Peak 

Note From Kakinoki et al., Dove, and Poltavtsev et al. as compared to graphite. 

Sources Data from J. Kakinoki, K. Katada, T. Hanawa, and T. Ino. Electron diffraction study of evaporated carbon films. Acta Cryst. 13, 171-179 (1960) D.B. Dove. Structure of amorphous films using direct recording electron diffraction. 26th Annual EMSA Meeting, 396-397 (1968) Y.G. Poltavtsev, V.P. Zakharov, and M.V. Pozdnyakova. Electron diffraction analysis of amorphous films of carbon and boron. Sov. Phys. Crystallogr. 18,270-271 (1973). With permission. 

Radial Distribution Functions P(,x) of the Carbon Films Listed in Table 1.1 as Compared to Graphite (Calculated in Richter et al., 1956 [11]) 

---

A fascinating study on the surface science of copper hydride on Si02, as well as on AI2O3, ceria (cerium oxide), and ZnO, has appeared [50]. Pure, yet thermally unstable, CuH can be precipitated as a red-brown solid from aqueous cupric sulfate and hypophosphorous acid in the presence of H2SO4, and has been characterized by powder X-ray diffraction (PXRD) (Eq. 5.25). Transmission electron microscopy (TEM) data suggest that it is most stable when deposited on acidic Si02. 

Abstract Gold and silver nanoparticles were obtained by in situ reduction with silicon hydride groups grafted to the mesoporous MCM-41 silica surface. Nickel-, eobalt-, and iron-containing silicas were synthesized by chemisorption of appropriate metal aeetylacetonates with following reduction in the acetylene atmosphere. Such metal-containing MCM-41 matrices have been applied for preparation of carbon nanostructures at pyrolytie deeomposition of acetylene. From transmission electron microscopy (TEM) data a lot of carbon nanotubes were formed, namely tubes with external diameter of 10-35 nm for Ni-, 42-84 nm for Co-, and 14—24 nm for Fe-eontaining silieas. In the metal absence on the silica surface low yield of nanotubes (up to 2%) was detected. 

According to transmission electron microscopy (TEM) data [13]> supporting of Ru3(CO)i2 Pd/Si02 and subsequent reduction leads to a 2-3 A increase in the size of metallic particles, the size distribution remaining quite narrow. 

Powder X-ray diffraction (XRD) data were collected via a Siemens D5005 diffractometer with CuKa radiation (A. = 1.5418 A). Routine transmission electron microscopy (TEM) and Z-contrast microscopy were carried out using an HITACH HD-2000 scanning transmission electron microscope (STEM) operated at 200 kV. Nitrogen gas adsorption measurements (Micromeritics Gemini) were used to determine the surface area and porosity of the catalyst supports. Inductively coupled plasma (ICP) analysis was performed via an IRIS Intrepid II XSP spectrometer (Thermo Electron Corporation). 

In contrast transmission electron microscopy (TEM) can in skilled hands yield detailed quantitative data on pore structure, and can even provide valuable information on the wet state of resins by plunge freezing such samples and microtom-ing on a cold stage [105]. To obtain quantitative information it is necessary to use advanced image analysis methodology which is extremely powerful [106]. Unfortunately the approach is time consuming and costly and can rarely be applied routinely in morphology studies. 

Transmission electron microscopy (TEM) can provide valuable information on particle size, shape, and structure, as well as on the presence of different types of colloidal structures within the dispersion. As a complication, however, all electron microscopic techniques applicable for solid lipid nanoparticles require more or less sophisticated specimen preparation procedures that may lead to artifacts. Considerable experience is often necessary to distinguish these artifacts from real structures and to decide whether the structures observed are representative of the sample. Moreover, most TEM techniques can give only a two-dimensional projection of the three-dimensional objects under investigation. Because it may be difficult to conclude the shape of the original object from electron micrographs, additional information derived from complementary characterization methods is often very helpful for the interpretation of electron microscopic data. 

In the author s opinion, the better approach to experimentally study the morphology of the silica surface is with the help of physical adsorption (see Chapter 6). Then, with the obtained, adsorption data, some well-defined parameters can be calculated, such as surface area, pore volume, and pore size distribution. This line of attack (see Chapter 4) should be complemented with a study of the morphology of these materials by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning probe microscopy (SPM), or atomic force microscopy (AFM), and the characterization of their molecular and supramolecular structure by Fourier transform infrared (FTIR) spectrometry, nuclear magnetic resonance (NMR) spectrometry, thermal methods, and possibly with other methodologies. 

---