Analysis by TEM

An example of a study in which this approach was applied involved the use of a transmission electron microscopy (TEM) grid as the collector plate in the electrostatic precipitator (Witkowski et a ., 1988). After sample collection, analysis by TEM (vide infra) could then be carried out. 

Lead Analysis by TEMS. Lead analyses are made using the gel technique described by Cameron et al. (10). Lead ions are thermally produced at rhenium filament temperatures between 1100-1300°C, depending on the sample size. Ten ng of sample allows an analysis of 10 runs with 200 sweeps each across the masses of interest. 

Morphological changes in the surface of Co-PFS films after RIE were investigated by TEM and AFM. Thin films of the polymer (ca. 50 nm thick) on a carbon-coated copper TEM grid were exposed to oxygen and hydrogen plasma. In both cases, analysis by TEM revealed the presence of electron-rich nanoworms with... 

Figure 10 shows the atomic force microscopic (AFM) image of the nanobands prepared fi-om a mixture of PLLA-PEG (5000-5000) and PDLA-PEG (5000-5000) micellar solutions. Each solution was 0.01 wt% in water, mixed at room temperature, cast on the mica surface, and then heated at 60 °C for 1 h. As observed fi-om a single polymer system of PLLA-PEG, the mixed system also forms similar crystal nanobands. Extremely interesting is that they are aligned in pair (Figure 10). Analysis by TEM diffraction revealed that that both bands in pair consist of the single PLLA and/or PDLA crystals. These facts suggest that the PEG blocks connected with PLLA and PDLA interact so strongly prior to...

An EDX spectrum typical of thin-film analysis in TEM/(S)TEM is shown in Eig. 4.26. It was obtained from a polycrystalline TiC/Zr02 ceramic by use of an Si(Li) detector at 100 keV primary electron energy. Eor spectrum recording the electron probe of approximately 1 nm in diameter was focused on the triple junction between the grains in the STEM mode (Eig. 4.26a). Besides the elements expected for the material under investigation, viz. Ti and Zr, Si, Ee, and Co were also detected, hinting at the presence of a (Ee, Co) silicide as an impurity. Eor ceramic materials it is known that... 

The bending of the graphite planes necessary to form a buckytube changes the band parameters. The relevant dimensionless parameter is the ratio a/R, where a ( = 3.4 A) is the lattice constant and R is the buckytube radius. For / = 20 A, the shift is expected to alter the nature of the conductivity[13-16j. In our buckybundle samples, most of material involves buckytubes with R > 100 A confirmed by statistical analysis of TEM data, and we assume that the elec-... 

Dravid et al. examined anisotropy in the electronic structures of CNTs from the viewpoint of momentum-transfer resolved EELS, in addition to the conventional TEM observation of CNTs, cross-seetional TEM and precise analysis by TED [5]. Comparison of the EEL spectra of CNTs with those of graphite shows lower jc peak than that of graphite in the low-loss region (plasmon loss), as shown in Fig. 7(a). It indicates a loss of valence electrons and a change in band gap due to the curved nature of the graphitic sheets. 

An alternative mode for dehydrobenzoannulene decomposition was recently reported by Vollhardt et al. [58]. Non-planar hybrid 81, prepared in low yield via cyclodimerization of known triyne 82 [Eq.(3)], reacted explosively at ca. 250°C to give a nearly pure carbon residue. Solvent extraction of the black powder failed to yield soluble materials such as fullerenes however, analysis of the residue by TEM showed formation of bucky onions and bucky tubes [59], in addition... 

The use of DNA as a template to fabricate mesoscale structures was also demonstrated in a recent work of Torimoto and coworkers. They used preformed, positively charged 3-nm CdS nanoparticles with a thiocholine-modified surface to be assembled into chains by using the electrostatic interaction between positively charged nanoparticle snr-faces and the phosphate groups of DNA. As determined by TEM analysis, the CdS nanoparticles were arranged in a qnasi-one-dimensional dense packing. This revealed interparticle distances of about 3.5 nm, which is almost equal to the height of one helical tnm of the DNA double strand [98]. 

The surface analyses of the Co/MgO catalyst for the steam reforming of naphthalene as a model compound of biomass tar were performed by TEM-EDS and XPS measurements. From TEM-EDS analysis, it was found that Co was supported on MgO not as particles but covering its surface in the case of 12 wt.% Co/MgO calcined at 873 K followed by reduction. XPS analysis results showed the existence of cobalt oxide on reduced catalyst, indicating that the reduction of Co/MgO by H2 was incomplete. In the steam reforming of naphthalene, film-like carbon and pyrolytic carbon were found to be deposited on the surface of catalyst by means of TPO and TEM-EDS analyses. 

ESCA analysis showed a similar trend of incomplete surface coverage for the IK systems. Also, no domains were visible in any of the IK styrenic graft systems by TEM. There is an expected trend with respect to solubility parameter, p(t-butyl styrene) (6 s 8.1) has a solubility parameter much closer to that of polydimethylsiloxane (S a 7.3) than does p(p-methyl styrene) which is closer than p(styrene) (S s 9.1). 

The particle size was below 50 nm (as determined by TEM image analysis), considerably smaller than that of the starting nanoemulsion, and showed a slight mean particle size increase and a broader size distribution with increasing O/S ratio, supporting the template effect of the nanoemulsion. The authors showed that these nanoparticles are interesting not only from a basic viewpoint but also for applications where safety and environmental concerns are important issues. 

Precise thickness measurements by TEM require sections transverse to the basal lamellar surface. Conversely, only lamellae that can be identified as untilted "edge-on" or "flat-on" in AFM images are suitable for thickness analysis. The average thickness obtained by these techniques is based on sampling microscopic areas and will only be correct if the morphology is uniform in the sample. Micrographs taken from different areas of the specimen are usually studied, and statistical analysis of histograms used for quantitative analysis [255,256]. 

---