Normalized aperture exposure

Fourier transform IR, accuracy, 376 NMR, accuracy, 376 Annealing, for analysis, 129 Anthracene, bound to polyionene, 189 Aperture exposure, normalized, 29 Argon ion lasers, 210, 212-14 Aromatic groups in polymers, effect on sensitivity, 146 Aromatic polymers, 145... 

The required exposure times are difficult to estimate. They are best found by trial and error. Documentation of fluorescence quenching at A = 254 nm usually only requires one trial. The exposure time found to be adequate here is normally suitable for all following exposures of fluorescence quenching if the exposure conditions are maintained constant (camera type, film type, distance of objective and lamp, aperture etc.). The exposure time required for fluorescent chromatograms is primarily dependent on the intensity of the fluorescence and, therefore, has to be optimized for each chromatogram. It is best to operate with a range of exposure times, e.g. aperture 8 with exposures of 15,30,60,120 and 240 seconds. Experience has shown that one exposure is always optimal. 

Figure 11. Exposure received at the center of an aperture, normalized to the exposure at the center of a large shape, for electron beam and optical cases.

Quantitative Processing. Plates or film with the diffraction patterns were scanned with a Joyce-Loebl microdensitometer. Radial (20) densitometric plots of the crystalline pattern (eventually three successive exposures of the crystalline pattern are analyzed) and of the corresponding amorphous pattern were recorded on the same curve. In this way, the plot of the amorphous pattern was used as a reference standard. The densitometric recording began with the optical density of the non-irradiated emulsion this allowed the evaluation and normalization of the optical density of the diffraction pattern. When the analytical slit passed through the image of the border of the 75 pm objective aperture, the densitometric curve showed a sudden density raise "A d". (Fig. 6) The plots of the amorphous and crystalline patterns were thus normalized to the same reference " A d". Crystallinity was determined on the normalized curves by measuring the areas "C + A" and "A" under the crystalline and amorphous plots respectively. 

Normally the total observational time is shared between many targets which can not be combined in the telescope field of view. Therefore, expansion of the telescope aperture, in practice, would result in the increase of total exposure, i.e. the experiment sensitivity. An ideal instrument, one could imagine, should be an all-directional telescope observing all the sources in the sky simultaneously. 

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