Peaks broad

In addition to sp C—H stretching modes there are other stretching vibrations that appear at frequencies above 3000 cm The most important of these is the O—H stretch of alcohols Figure 13 34 shows the IR spectrum of 2 hexanol It contains a broad peak at 3300 cm ascribable to O—H stretching of hydrogen bonded alcohol groups In... 

Identify compound A (CgHioO) on the basis of its H NMR spectrum (Figure 15 10) The broad peak at 8 2 1 disappears when D2O is added... 

The chemical shift of the N—H proton of amides appears m the range 8 5-8 It IS often a very broad peak sometimes it is so broad that it does not rise much over the baseline and can be lost m the background noise... 

Figure 4.7 Various representations of the properties of a mixture of crystalline and amorphous polymer, (a) The monitored property is characteristic of the crystal and varies linearly with 0. (b) The monitored property is characteristic of the mixture and varies linearly with 0 between and P, . (c) X-ray intensity is measured with the sharp and broad peaks being P. and P., respectively.

Figure 4.7c illustrates how x-ray diffraction techniques can be applied to the problem of evaluating 6. If the intensity of scattered x-rays is monitored as a function of the angle of diffraction, a result like that shown in Fig. 4.7c is obtained. The sharp peak is associated with the crystalline diffraction, and the broad peak, with the amorphous contribution. If the area A under each of the peaks is measured, then... 

X-ray diffraction work (11,15) shows that there is an ionomer peak at 4°C which is absent in the acid precursor. This low, broad peak is not affected by annealing or ion type and persists up to 300°C. Since the 4°C peak corresponds to a spacing of about 2.5 nm, it is reasonable to propose a stmctural feature of this dimension in the ionomer. The concept of ionic clusters was initially suggested to explain the large effects on properties of relatively sparse ionic species (1). The exact size of the clusters has been the subject of much debate and has been discussed in a substantial body of Hterature (3,4,18—20). A theoretical treatment has shown that various models can give rise to supramoleculat stmctures containing ionic multiplets which ate about 10 nm in diameter (19). 

Diffraction of x-rays from many atoms with many electrons results in a two-dimensional continuous pattern of peaks and valleys. Diffraction from a hquid or an amorphous (noncrystalline) soHd results in a continuous pattern with few features, mainly broad peaks and valleys. 

When the hydropathy indices are plotted against residue numbers, the resulting curves, called hydropathy plots, identify possible transmemhrane helices as broad peaks with high positive values. Such hydropathy plots are shown in Figure 12.23 for the L and M chains of the reaction center. 

With modern detectors and electronics most Enei -Dispersive X-Ray Spectroscopy (EDS) systems can detect X rays from all the elements in the periodic table above beryllium, Z= 4, if present in sufficient quantity. The minimum detection limit (MDL) for elements with atomic numbers greater than Z = 11 is as low as 0.02% wt., if the peaks are isolated and the spectrum has a total of at least 2.5 X 10 counts. In practice, however, with EDS on an electron microscope, the MDL is about 0.1% wt. because of a high background count and broad peaks. Under conditions in which the peaks are severely overlapped, the MDL may be only 1—2% wt. For elements with Z < 10, the MDL is usually around 1—2% wt. under the best conditions, especially in electron-beam instruments. 

These aspects of the optical spectra of solids are illustrated in the upper portion of Figure 1, which displays the reflectance curve (R) at room temperature for a typical semiconductor, GaAs. The fundamental absorption edge around 1.4 eV produces only a weak shoulder. Some structure is apparent in the two features around 3 eV and the large, broad peak near 5 eV. However, the dominant aspect of the line shape is the slowly varyii background. The derivative namre of Modulation Spectroscopy suppresses the uninteresting background effects in favor of sharp, deriva-... 

The )3 relaxation is very broad for the two polybibenzoates (Fig. 15) and appears at around -60°C. It has a complex origin, is characteristic of polyesters, and originates from movements of phenyl and carboxyl groups. The very broad peaks observed in Fig. 15 are the consequence of this complex character. 

Properties of the activation product. The two decylamine-activation products (luciferins) showed similar absorption characteristics (A.max 372 nm in water, and 375 nm in ethanol), which clearly differ from the absorption peak of the natural luciferin (320 nm) reported by Kuwabara and Wassink (1966). The fluorescence emission of the activation products varied significantly by solvents, showing a peak at 460 nm in neutral aqueous solution and a broad peak at 485-522 nm in ethanol. They emitted chemiluminescence (A.max 580 nm) in the presence of CTAB, H2O2 and Fe2+ (Fig. 9.13), in resemblance to the (NH4)2S04-activation product of panal (A.max 570 nm). 

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