Electron microscopy preparation

Chemical fixation for transmission electron microscopy prepares cells for the preservation of damage due to subsequent washing with aqueous solvents, dehydration with organic solvents such as ethanol or acetone, embedding in plastic resins, polymerization of the resins by heat, exothermic catalysts, or ultraviolet radiation, and imaging with high-energy electron beams in an electron microscope. 

For electron microscopy prepare sections (thickness 20 pm) on a vibration microtome while fragments are immersed in cacodylate buffer. At this stage Pickel et al. incubated the sections with 0.2% Triton X-100 for 30 min to improve specific detection. 

These authors have used the technique of lamellar decoration [76] which enables detailed assessment of cheu-acteristic mesophase defects and texture on a much finer scale than previously possible with conventional electron-microscopy preparations. The defects and texture existing in the polymer melt state are first retained by thermal quenching of the polymer fluid to room temperature. The glassy LCP film is then annealed above its glass transition, but below the melting point. Crystalline lamellae grow perpendicular to the local chain axis and effectively decorate the molecular director... 

The detection limits are determined by the number of fibers in suitably prepared blank filters and by the random nature of the filter and of the search. In some electron microscopy preparations, where no fibers are found in the blank controls, the detection limit has been taken as 3.69 times the sensitivity (the upper 95% confidence limit for zero in a Poisson distribution). Otherwise, as in PCOM, where a nonzero blank control is common, a higher detection limit prevails. Thus a series of blank filters might produce an average fiber count of five fibers in a standard analysis, which for routine air samples ( 0.5m ) could translate into a detection limit of 0.01 fibers per milliliter. 

Scanning electron microscopy preparations are generally direct and rapid, yet there are quite a number of potential artifacts. Paints, glues, and tapes used to attach the specimen to the SEM stub can wick up or contaminate the specimen surfaces, adding false structures to the... 

Transmission electron microscopy is very widely used by biologists as well as materials scientists. The advantage of being able to resolve 0.2 nm outweighs the disadvantages of TEM. The disadvantages include the inabiUty of the common 100-kV electron beam to penetrate more than a few tenths of a micrometer (a 1000-kV beam, rarely used, penetrates specimens about 10 times thicker). Specimen preparation for the TEM is difficult because of the... 

A variety of instmmental techniques may be used to determine mineral content. Typically the coal sample is prepared by low temperature ashing to remove the organic material. Then one or more of the techniques of x-ray diffraction, infrared spectroscopy, differential thermal analysis, electron microscopy, and petrographic analysis may be employed (7). 

Thin films of metals, alloys and compounds of a few micrometres diickness, which play an important part in microelectronics, can be prepared by die condensation of atomic species on an inert substrate from a gaseous phase. The source of die atoms is, in die simplest circumstances, a sample of die collision-free evaporated beam originating from an elemental substance, or a number of elementary substances, which is formed in vacuum. The condensing surface is selected and held at a pre-determined temperature, so as to affect die crystallographic form of die condensate. If diis surface is at room teiiiperamre, a polycrystalline film is usually formed. As die temperature of die surface is increased die deposit crystal size increases, and can be made practically monocrystalline at elevated temperatures. The degree of crystallinity which has been achieved can be determined by electron diffraction, while odier properties such as surface morphology and dislocation sttiicmre can be established by electron microscopy. 

K. C. Thompson-Russell and J. W. Edington. Electron Microscope Specimen Preparation Techniques in Materials Science. Monographs in Practical Electron Microscopy, No. 5- Philips Technical Library, Eindhoven Delaware, 1977. 

Specimen Preparation for Transmission Electron Microscopy I. (J. C. Brav-man, R. M. Anderson, and M. L. McDonald, eds.) Volume 115 in MRS symposium proceedings series, 1988. 

In contrast to many other surface analytical techniques, like e. g. scanning electron microscopy, AFM does not require vacuum. Therefore, it can be operated under ambient conditions which enables direct observation of processes at solid-gas and solid-liquid interfaces. The latter can be accomplished by means of a liquid cell which is schematically shown in Fig. 5.6. The cell is formed by the sample at the bottom, a glass cover - holding the cantilever - at the top, and a silicone o-ring seal between. Studies with such a liquid cell can also be performed under potential control which opens up valuable opportunities for electrochemistry [5.11, 5.12]. Moreover, imaging under liquids opens up the possibility to protect sensitive surfaces by in-situ preparation and imaging under an inert fluid [5.13]. 

S. Amelincks, D. van Dyck, J. van Landuyt, G. van Tendeloo (eds.) Electron Microscopy Principles and Fundamentals,VCH Verlagsgesellschaft mbH, Weinheim 1997. 2-178 R. M. Anderson, S. D. Walck (eds.) Specimen Preparation for Transmission Electron Microscopy of Materials IV, Materials Research Society, Pittsbrrrgh 1997. 

Regarding a historical perspective on carbon nanotubes, very small diameter (less than 10 nm) carbon filaments were observed in the 1970 s through synthesis of vapor grown carbon fibers prepared by the decomposition of benzene at 1100°C in the presence of Fe catalyst particles of 10 nm diameter [11, 12]. However, no detailed systematic studies of such very thin filaments were reported in these early years, and it was not until lijima s observation of carbon nanotubes by high resolution transmission electron microscopy (HRTEM) that the carbon nanotube field was seriously launched. A direct stimulus to the systematic study of carbon filaments of very small diameters came from the discovery of fullerenes by Kroto, Smalley, and coworkers [1], The realization that the terminations of the carbon nanotubes were fullerene-like caps or hemispheres explained why the smallest diameter carbon nanotube observed would be the same as the diameter of the Ceo molecule, though theoretical predictions suggest that nanotubes arc more stable than fullerenes of the same radius [13]. The lijima observation heralded the entry of many scientists into the field of carbon nanotubes, stimulated especially by the un-... 

Here, we will describe experimental studies on capillary filling of CNTs. Because of the focus of this chapter, we have taken examples from the work in our own laboratory certainly we may have inadvertently ignored other exciting work from other laboratories in the world. Still the preparation of a sample of purified and filled CNTs have yet to be developed, so that the study of filled tubes have been and can only be performed by electron microscopy and associated techniques. We have tried to describe in detail all the steps involved in the procedure of capillary filling, such as CNT production, opening, filling and final thermal processing. 

Alloys were prepared by arc melting high purity starting materials followed by homogenisation. Transmission electron microscopy specimens were prepared by... 

Although most solutions satisfy the three-component criterion they have usually been established by empirical methods and their compositions can be found by referring to tables on a recipe-book basis Many have been extensively explored by metallographers in search of improved preparation techniques, notably for electron microscopy . ... 

Aluminium is widely applied for decorative and protective requirements, while cadmium , zinc and titanium have been applied to ferrous materials chiefly for their protective value. The method finds particular application in the plating of high-tensile steels used in aviation and rocketry, car fittings and lamp reflectors, and gramophone record master discs, as well as in the preparation of specimens for electron microscopy and in rendering insulated surfaces electrically conducting, e.g. metallising of capacitors and resistors. 

In this case, the elements of the crosslinked structure exhibit higher mobility, the permeability of the crosslinked structure depends on the degree of hydration. It should be noted that the pore size in hydrated crosslinked copolymers is determined by small-angle X-ray scattering or with the aid of electron microscopy using special methods of preparation for the CP samples [15],... 

Glad [37] studied the micro deformations of thin films prepared from DGE-BA/MDA by electron microscopy. His results are also shown in Fig. 7.5. The deformation of the sample with high strand density was small and consequently its image in the EM rather blurred. Therefore, the result on Mc = 0.5 kg/mol should perhaps have been omitted. 

Also a good interface resolution is obtained with transmission electron microscopy (TEM), where, however, a dedicated sample preparation and treatment are necessary to achieve nanometer resolution and suitable contrast [64]. Thus the... 

Scanning electron microscopy and replication techniques provide information concerning the outer surfaces of the sample only. Accurate electron microprobe analyses require smooth surfaces. To use these techniques profitably, it is therefore necessary to incorporate these requirements into the experimental design, since the interfaces of interest are often below the external particle boundary. To investigate the zones of interest, two general approaches to sample preparation have been used. 

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