Low dose TEM

To understand further and confirm our interpretation of the SAXS data, we complemented these results with a study using freeze fracture electron microscopy (FFEM) as well as low dose TEM (Eig. 5). This allowed us to show that in NMF NaNb2PSio folds into single walled nanotubules having wall thickness of... 

TEM instruments and the improved operation procedures using devices such as a Minimum Dose System (MDS JEOL Ltd.) or a Low Dose Unit (LDU Philips) [2,3],... 

Figure 1.10 TEM image of a VPO catalyst (no promoters, prepared by the alcohol method after 100 h equilibration in feed) as 200 keV electrons at a low dose of below 10 A cm-2 were used the beam damage can account for only approximately half of the overlayer seen above the (100) lattice image of VPO.

SAED is the most popular diffraction technique in TEM. The technique can be applied to study both crystalline and noncrystalline structmes. The large area illumination is useful for recording diffraction patterns from polycrystalline samples or averaging over a large volume (e.g., a large number of nanoparticles). SAED can also be used for low-dose electron diffraction, which is required for studying radiation sensitive materials, such as organic molecules. 

A question still remains about the structure of the polymer within the walls of these nanotubules. The very low stability of theses tubes under TEM irradiation, even when applying low doses, precluded us so far from observing high-resolution images. An electron diffraction pattern highly reminiscent of a heli-coidal organization of the polymer was observed but this still needs to be confirmed and studied in more detail. 

Fig. 13 Effect of increasing on the shape of the crystalline domains of slow-DEC P3HT samples as observed by low dose HR-TEM. Low-M ,...

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