TEM alignment

The objective lens is the most important lens for a transmission electron microscope. The condenser lenses are the next most important, the combination of these condenser lenses forms different electron beam to illuminate TEM specimens. The first lens of the projector system (also called the intermediate or diffraction lens) is the third most important one. All the other lenses can be ignored, even though they magnify images. Since the objective lens is the most important, the center of the objective is acmally the optical axis, every other lenses must be aligned with it. TEM alignment starts from top to the bottom. 

After finishing the above basic TEM alignment, the microscope is ready for further TEM experiments and alignments. 

Check one more time the TEM alignment, especially pay attention to specimen height, pivot point alignment and beam-tilt alignment. 

Multi-walled CNTs (MWCNTs) are produced by arc discharge between graphite electrodes but other carbonaceous materials are always formed simultaneously. The main by-product, nanoparticles, can be removed utilizing the difference in oxidation reaction rates between CNTs and nanoparticles [9]. Then, it was reported that CNTs can be aligned by dispersion in a polymer resin matrix [10]. However, the parameters of CNTs are uncontrollable, such as the diameter, length, chirality and so on, at present. Furthermore, although the CNTs are observed like cylinders by transmission electron microscopy (TEM), some reports have pointed out the possibility of non-cylindrical structures and the existence of defects [11-14]. 

Fig. 11 Formation of crystalline 3D super-lattices of tin nanoparticles a TEM view of a facetted super-crystal b SEM image showing particles included into a super-crystal as well as the organic surrounding c High resolution micrograph showing the alignment of the tin atomic planes inside the super-structure...

The crystals of akaganeite are not microporous. Micropores observed by TEM are considered to be due to irradiation in the electron beam (Galbrait et al., 1979 Naono et al., 1982). Open ended, cylindrical, interparticular micropores have been reported these arose as a result of alignment of the rod-like crystals into parallel arrays (Paterson and Tait, 1977). Akaganeite does possess a potential structural microporosity arising from the presence of 0.21-0.24 nm across tunnels in the structure. At room... 

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