Lateral resolving power

The spatial resolving power will be described for three concrete cases (i) Lateral resolving power characterizing fine scans as shown in Fig. 7.12b... 

Estimated values of the lateral resolving power of some distribution-analytical methods are shown in Table 7.7 (Eckschlager and Danzer [1994])... 

An important factor influencing the lateral resolving power of the system is the dynamic aperture this is achieved by activating variable numbers of elements dynamically to optimize focusing at many depths. 

The concept of the effective plate number was introduced and employed in the late nineteen fifties by Purnell (7), Desty (8) and others. Its introduction arose directly as a result of the development of the capillary column, which, even in 1960, could be made to produce efficiencies of up to a million theoretical plates (9). It was noted, however, that these high efficiencies were were only realized for solutes eluted close to the column dead volume, that is, at very low k values. Furthermore, they in no way reflected the increase in resolving power that would be expected from such high efficiencies on the basis of the performance of packed columns. This poor performance, relative to the high efficiencies produced, can be shown theoretically ( and Indeed will be, later in this book) to result from the high phase ratio of capillary columns made at that time. That is the ratio of the mobile phase to the stationary phase in the column. The high phase ratio was... 

To understand the resolution of electron microscopes and later diffraction techniques the wave approach is more instructive. The resolving power of electron microscopes is substantially better than that of a light microscope, since the wavelength of the electrons, given by the de Broglie relation... 

It should be noted that the anomerization effect upon the structural-reporter group signals of 35 is only observable for those of GlcNAc-2 and Man-3, probably due to the lower resolving power of the 360-MHz with respect to the 500-MHz spectrometer. Apparently, the effect of anomerization on the various structural-reporter groups is similar to that for 17, as will later be considered in more detail (for example, 36 and 37). 

Thomson s apparatus did not permit very accurate results to be obtained. The method was increased in accuracy by F. W. Aston, also working in the Cavendish Laboratory, arid later by A. J. Dempster of the University of Chicago, and other American physicists. Modern types of mass spectrographs (Fig. 7-3) have an accuracy of about one part in 100,000 and a resolving power of 10,000 or more (that is, they are able to separate ion beams with values of M/n differing by only one part in 10,000). 

The early speculations about transition moment directions in the lower aromatics needed to be tested experimentally. The traditional vapour phase measurements of band lineshapes were not accessible with the spectroscopic resolving power we then had, but came later (sec 4.2). Most absorption systems of aromatics in the UV were in any case diffuse and structureless. The method that could be used was to get the polarization of the light absorbed by the crystal composed of the target molecules. The positions and orientations of the molecules in the laboratory frame were known from X-ray crystal structure analysis. The interpretation of results raised non-trivial theoretical problems of its own. The experiments will be described first. 

Other factors affecting the choice of a crystal are its reflecting power and resolving power. These properties are discussed later. 

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