Scanning electron microscopy SEM method

SEM methods. See Scanning electron microscopy (SEM) methods Semliki Forest virus (SFV), 61, 353-354 El Ca backbone, 382 El glycoprotein atomic structure of, 381 resolution reconstruction of, 62 Semliki Forest virus (SFV) /tick-bome... 

However, the preparation for transmission electron microscopy (TEM), requiring thin samples (less than 100 nm) to allow the electron beam to penetrate the sample, will be discussed separately from scanning electron microscopy (SEM) methods since these normally require bulk preparation where sample stability and conductivity are the main criteria. 

Scanning electron microscopy allows a clear view of the overall strucnire of a microfiltration membrane the top surface, the cross-section and the bonom surface can all.. be observed very nicely. In addition, any asymmetry in the structure can be readily observed. Figure IV - 5 shows the top surface of a porous poly(ether imide) membrane [5] as observed by scanning electron microscopy (SEM) methods. Micrographs of this kind allow the pore size, the pore size distribution and the surface porosity to be obtained. Also the geometry of the pores can be clearly visualised. 

The interface properties can usually be independently measured by a number of spectroscopic and surface analysis techniques such as secondary ion mass spectroscopy (SIMS), X-ray photoelectron spectroscopy (XPS), specular neutron reflection (SNR), forward recoil spectroscopy (FRES), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), infrared (IR) and several other methods. Theoretical and computer simulation methods can also be used to evaluate H t). Thus, we assume for each interface that we have the ability to measure H t) at different times and that the function is well defined in terms of microscopic properties. 

Further structural information is available from physical methods of surface analysis such as scanning electron microscopy (SEM), X-ray photoelectron or Auger electron spectroscopy (XPS), or secondary-ion mass spectrometry (SIMS), and transmission or reflectance IR and UV/VIS spectroscopy. The application of both electroanalytical and surface spectroscopic methods has been thoroughly reviewed and appropriate methods are given in most of the references of this chapter. 

Suhtnicion nickel powders luive been synthesized successfully from aqueous NiCh at various tempmatuTKi and times with ethanol-water solvent by using the conventional and ultrasonic chemical reduction method. The reductive condition was prepared by flie dissolution of hydrazine hydrate into basic solution. The samples synthesized in various conditions weae claractsiz by the m ins of an X-ray diffractometry (XRD), a scanning electron microscopy (SEM), a thermo-gravimetry (TG) and an X-ray photoelectron spectroscopy (XPS). It was found that the samples obtained by the ultrasonic method were more smoothly spherical in shape, smaller in size and narrower in particle size distribution, compared to the conventional one. 

Nanosized anatase (< 10 nm) and brookite ( 70 run) particles have been successfully synthesized via sonication and hydrothermal methods. Figure 5.1 shows the powder XRD patterns of as-synthesized anatase and brookite nanoparticles. The particle sizes were characterized by XRD and scanning electron microscopy (SEM) (Fig. 5.2). 

Scanning electron microscopy (SEM) seems to have been used only scarcely for the characterization of solid lipid-based nanoparticles [104], This method, however, is routinely applied for the morphological investigation of solid hpid microparticles (e.g., to smdy their shape and surface structure also with respect to alterations in contact with release media) [24,38,39,41,42,80,105]. For investigation, the microparticles are usually dried, and their surface has to be coated with a conductive layer, commonly by sputtering with gold. Unlike TEM, in SEM the specimen is scanned point by point with the electron beam, and secondary electrons that are emitted by the sample surface on irradiation with the electron beam are detected. In this way, a three-dimensional impression of the structures in the sample, or of their surface, respectively, is obtained. 

Preparation As compared to single-crystal Ag surfaces, the preparation of pc-Ag electrode may seem to be a relatively simple task. However, a pc-Ag surface, which ensures reproducibility and stabiKty, also requires a special procedure. Ardizzone et al. [2] have described a method for the preparation of highly controlled pc-Ag electrode surface (characterized by electrochemical techniques and scanning electron microscopy (SEM)). Such electrodes, oriented toward elec-trocatalytic properties, were successfully tested in hahde adsorption experiments, using parallelly, single-crystal and conventional pc-Ag rods as references. 

Because of the instrumental requirements, these are usually not routine monitoring techniques. However, unlike other methods, they give detailed information on particle shapes. In addition, chemical composition information can be obtained using transmission electron microscopy (TEM) or scanning electron microscopy (SEM) combined with energy-dispersive spectrometry (EDS). The electron beam causes the sample to emit fluorescent X-rays that have energies characteristic of the elements in the sample. Thus a map showing the distribution of elements in the sample can be produced as the electron beam scans the sample. 

Although a number of secondary minerals have been predicted to form in weathered CCB materials, few have been positively identified by physical characterization methods. Secondary phases in CCB materials may be difficult or impossible to characterize due to their low abundance and small particle size. Conventional mineral identification methods such as X-ray diffraction (XRD) analysis fail to identify secondary phases that are less than 1-5% by weight of the CCB or are X-ray amorphous. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM), coupled with energy dispersive spectroscopy (EDS), can often identify phases not seen by XRD. Additional analytical methods used to characterize trace secondary phases include infrared (IR) spectroscopy, electron microprobe (EMP) analysis, differential thermal analysis (DTA), and various synchrotron radiation techniques (e.g., micro-XRD, X-ray absorption near-eidge spectroscopy [XANES], X-ray absorption fine-structure [XAFSJ). 

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