Absolute-intensity representation

Fig. 16. Representation of the electron density in terms of step functions inside the smectic layer. X-rays being only sensitive to the contrast, the electronic density of the mesogenic cores has been arbitrarily assigned to zero. Since we do not make absolute intensity measurements and since we deal with a purely displacive disorder, the backbones and the spacers have been represented by two different step functions of equal hatched areas. The resulting electron density profile is shown in thick broken line. M, S and B stand for the mesogenic cores, spacers and backbones regions respectively...

The most intense peak of a mass spectrum is called base peak. In most representations of mass spectral data the intensity of the base peak is normalized to 100 % relative intensity. This largely helps to make mass spectra more easily comparable. The normalization can be done because the relative intensities are independent from the absolute ion abundances registered by the detector. However, there is an upper limit for the number of ions and neutrals per volume inside the ion source where the appearance of spectra will significantly change due to autoprotonation (Chap. 7). In the older literature, spectra were sometimes normalized relative to the sum of all intensities measured, e.g., denoted as % Lions, or the intensities were reported normalized to the sum of all intensities above a certain m/z, e.g., above m/z 40 (% L 4o)-... 

The scattered intensity is usually represented as the total number of the accumulated counts, counting rate (counts per second - cps) or in arbitrary units. Regardless of which units are chosen to plot the intensity, the patterns are visually identical because the intensity scale remains linear and because the intensity measurements are normally relative, not absolute. In rare instances, the intensity is plotted as a common or a natural logarithm, or a square root of the total number of the accumulated counts in order to better visualize both strong and weak Bragg peaks on the same plot. The use of these two non-liner intensity scales, however, always increases the visibility of the noise (i.e. highlights the presence of statistical counting errors). A few examples of the non-conventional representation of powder diffraction patterns are found in the next section. 

Intensity/wavelength/time cross-sectional diagrams (or time-resolved fluorescence "contour" diagrams) are generated using a weighted nonlinear least squares polynomial surface procedure (20). Area-normalized TRE spectra can be used for convenient pictorial representation, since the absolute emission intensity of individual time-resolved spectra vary substantially with time after excitation. 

Fig. 15.16. Representation of the quantity ql vI(q)/Kp plotted against q, in the asymptotic domain qRa > 1. The measurement of the scattered intensity is absolute here. Partially deuterated polystyrene (CD2—CHCSH6)W of molecular mass Mw = 1.2 x 102 in CS2. The extrapolation at gives the quantity we are looking for. Neutron...

The most intense peak of a mass spectrum is called base peak. In most representations of mass spectral data the intensity of the base peak is normalized to 100% relative intensity. This largely helps to make mass spectra more easily comparable. The normalization can be done because the relative intensities are basically indepenckait from the absolute ion abundances registered by the detector. 

The choice of dipole moment derivatives is one of the most difficult and crucial problem in infrared intensity theory. Only (3]Jq /3Q. ) are fixed by the experimental intensities. Considering any irreducible Representation, containing n infrared active modes, the number of (3p/9Q) -matrices is 2 which differ only in signs of the different elements ( d not in absolute value). 

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