Scanning principle

In addition, use of the scanning principle allows mlcroanalysls of very small specimen regions to be performed by detection of either the characteristic X-rays emitted cr the characteristic energy loss peaks in the energy spectrum of transmitted electrons. 

SFM combines the high force sensitivity of the surface force apparatus with the scanning principle of the profilometer. It enables measurement of weak forces as low as 1 pN with a spatial resolution down to 1 A. 

Figure 3.73. Step-and-scan principle. The wafer is exposed by synchronously scanning the mask and each wafer subfield through the illuminated zone of a ring-field imaging system. Reproduced with permission from reference 19. Copyright 1984 Technical Publishing.)...

Fig. 5. Ullrasonic C-scan principle (a) compared with A-scan and B-scan (b).

Keyboard is a contact matrix of dimension 3x4. In order to handle it, the principle of scanning buttons at running zero on input lines is used in SC EDC. 

The principle of the acquisition system is to translate the probe into a tube (including hemispherical drilled holes) step by step, every 0.04 mm, after a forwards and backwards 360 rotation of the tube trigging every 0.2° angular step a 360° electronic scanning of tube with the 160 acoustic apertures. During the electronic scanning the tube is assumed to stay at the same place. The acquisition lasts about 30 minutes for a C-scan acquisition with a 14 kHz recurrence frequency. 

Cork T and Kino G S 1996 Confocal Scanning Optical Microscopy and Related Imaging Systems (New York Academic) Gu Min 1996 Principles of Three Dimensional Imaging In Confocal Microscopes (Singapore World Scientific)... 

Figure Bl.19.1. Principle of operation of a scanning tiimrelling microscope. The x- andj -piezodrives scan the tip across the surface. In one possible mode of operation, the current from the tip is fed into a feedback loop that controls the voltage to die z-piezo, to maintam constant current. The Ime labelled z-displacement shows the tip reacting both to morphological and chemical (i.e. electronic) inliomogeneities. (Taken from [213].)...

Linked scanning techniques by which fragmentation reactions can be examined are particularly easy to apply with QqQ instmments. The ease with which RF and DC voltages can be changed rapidly means that the scanning can be done very quickly. Three common and popular types of linked scan are briefly described here and serve to illustrate its principles. 

Nobel-laureate Richard Feynman once said that the principles of physics do not preclude the possibility of maneuvering things atom by atom (260). Recent developments in the fields of physics, chemistry, and biology (briefly described in the previous sections) bear those words out. The invention and development of scanning probe microscopy has enabled the isolation and manipulation of individual atoms and molecules. Research in protein and nucleic acid stmcture have given rise to powerful tools in the estabUshment of rational synthetic protocols for the production of new medicinal dmgs, sensing elements, catalysts, and electronic materials. 

A. J. Bevolo. Scanning Electron Microscopy. 1985, vol. 4, p. 1449. (Scanning Electron Microscopy, Inc. Elk Grove Village, IL) Thorough exposition of the principles and applications of reflected electron energy-loss microscopy (REELM) as well as a comparison to other techniques, such as SAM, EDS and SEM. 

Fig. 5.2. Principle of AFM. The sample symbolized by the circles is scanned by means of a piezoelectric translator. The piezo crystal and the oscillator is only needed for tapping mode operation.

Scanning tunneling spectroscopy (STS) can, in principle, probe the electronic density of states of a singlewall nanotube, or the outermost cylinder of a multi-wall tubule, or of a bundle of tubules. With this technique, it is further possible to carry out both STS and scanning tunneling microscopy (STM) measurements at the same location on the same tubule and, therefore, to measure the tubule diameter concurrently with the STS spectrum. No reports have yet been made of a determination of the chiral angle of a tubule with the STM technique. Several groups have, thus far, attempted STS studies of individual tubules. 

The main technique employed for in situ electrochemical studies on the nanometer scale is the Scanning Tunneling Microscope (STM), invented in 1982 by Binnig and Rohrer [62] and combined a little later with a potentiostat to allow electrochemical experiments [63]. The principle of its operation is remarkably simple, a typical simplified circuit being shown in Figure 6.2-2. 

The very new techniques of scanning tunnelling microscopy (STM) and atomic force microscopy (AFM) have yet to establish themselves in the field of corrosion science. These techniques are capable of revealing surface structure to atomic resolution, and are totally undamaging to the surface. They can be used in principle in any environment in situ, even under polarization within an electrolyte. Their application to date has been chiefly to clean metal surfaces and surfaces carrying single monolayers of adsorbed material, rendering examination of the adsorption of inhibitors possible. They will indubitably find use in passive film analysis. 

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