Scanning-imaging microscopes

In scanning-imaging microscopes a small probe is passed over the specimen surface, and a signal is collected that relates to some local property of... 

The development of scanning probe microscopies and x-ray reflectivity (see Chapter VIII) has allowed molecular-level characterization of the structure of the electrode surface after electrochemical reactions [145]. In particular, the important role of adsorbates in determining the state of an electrode surface is illustrated by scanning tunneling microscopic (STM) images of gold (III) surfaces in the presence and absence of chloride ions [153]. Electrodeposition of one metal on another can also be measured via x-ray diffraction [154]. 

Figure Al.7.2. Large-scale (5000 Atimes 5000 A) scanning tiimielling microscope image of a stepped Si (111)-(7 X 7) surface showing flat terraces separated by step edges (courtesy of Alison Baski).

ESEM environmental scanning electron microscope ESI electron spectroscopic imaging... 

Hamers R, Avouris P and Boszo F 1987 Imaging of chemical-bond formation with the scanning tunnelling microscope NH, dissociation on Si(OOI) Rhys. Rev. Lett. 59 2071... 

Weiss P S and Eigler D M 1993 Site dependence of the apparent shape of a molecule in scanning tunnelling microscope images benzene on Pt(111) Rhys. Rev. Lett. 71 3139... 

Tang S L, McGhie A J and Suna A 1993 Molecular-resolution imaging of insulating macromolecules with the scanning tunnelling microscope via a nontunnelling, electric-field-induced mechanism Phys. Rev. B 47 3850... 

Bard A J, Fan F F, Pierce D T, Unwin P R, Wipf D O and Zhou F 1991 Chemicai imaging of surfaces with the scanning eiectrochemicai microscope Science 254 68... 

Sharp S L, Warmack R J, Goudonnet J P, Lee I and Ferrell T L 1993 Spectroscopy and imaging using the photon scanning-tunnelling microscope Acc. Chem. Res. 26 377... 

Kranz C, Wittstock G, Wohlschlager FI and Schumann W 1997 Imaging of microstructured biochemically active surfaces by means of scanning electrochemical microscope Electrochim. Acta 42 3105... 

Fisher A J and Bldchl P E 1993 Adsorption and scanning-tunneling-microscope Imaging of benzene on graphite and M0S2 Phys. Rev. Lett. 70 3263-6... 

Newer techniques that are responding to the need for atomic level imaging and chemical analysis include scanning tunneling microscopes (STMs), atomic force microscopes (AFMs) (52), and focused ion beams (FIBs). These are expected to quickly pass from laboratory-scale use to in-line monitoring apphcations for 200-mm wafers (32). 

Microscopy is an unusual scientific discipline, involving as it does a wide variety of microscopes and techniques. All have in common the abiUty to image and enlarge tiny objects to macroscopic size for study, comparison, evaluation, and identification. Few industries or research laboratories can afford to ignore microscopy, although each may use only a small fraction of the various types. Microscopy review articles appear every two years m. Jinalytical Chemistty (1,2). Whereas the style of the Enclyclopedia employs lower case abbreviations for analytical techniques and instmments, eg, sem for scanning electron microscope, in this article capital letters will be used, eg, SEM. 

There are also laser-scanning confocal microscopes rapidly overtaking the TSM as a means of confocal microscopy. There is also a computer software program that produces a "confocal" image by recogni2ing the shapes of out-of-focus detail, ie, halos, and subtracting these from the in-focus image. 

Computers will be integrated more and more into commercial SEMs and there is an enormous potential for the growth of computer supported applications. At the same time, related instruments will be developed and extended, such as the scanning ion microscope, which uses liquid-metal ion sources to produce finely focused ion beams that can produce SEs and secondary ions for image generation. The contrast mechanisms that are exhibited in these instruments can provide new insights into materials analysis. 

The electron-optical performance of the EPMA system is indistinguishable from that of a conventional scanning electron microscope (SEM) thus, EPMA combines all of the imaging capabilities of a SEM with quantitative elemental analysis using both energy- and wavelength-dispersive X-ray spectrometry. ... 

If an incident electron beam of sufficient energy for AES is rastered over a surface in a manner similar to that in a scanning electron microscope (SEM), and if the analyzer is set to accept electrons of Auger energies characteristic of a particular element, then an elemental map or image is again obtained, similar to XPS for the Quantum 2000 (Sect. 2.1.2.5). 

In electron-optical instruments, e.g. the scanning electron microscope (SEM), the electron-probe microanalyzer (EPMA), and the transmission electron microscope there is always a wealth of signals, caused by the interaction between the primary electrons and the target, which can be used for materials characterization via imaging, diffraction, and chemical analysis. The different interaction processes for an electron-transparent crystalline specimen inside a TEM are sketched in Eig. 2.31. 

Figure 6.5. Whiskers grown at 1150°C on surface of an iron aluminium alloy, imaged in an early scanning electron microscope x250 (Gardner and Cahn 1966).

Figure 6.6. The surface of a liii crystal following bombardment with 5 kcV argon ions, imaged in a. scanning electron microscope (Stewart and Thompson 1969).

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