Superposition of peaks

DMTA is a very interesting tool for characterizing heterogeneous materials in which domains of distinct Tg values coexist. The most interesting cases involve modified thermosets of different types (see Chapter 8). Examples are the use of rubbers (e.g., liquid polybutadiene and random copolymers), or thermoplastics (e.g., polyethersulphone or polyetherimide in epoxy matrices or poly(vinyl acetate) in unsaturated polyesters), as impact modifier (epoxies), or low-profile additives (polyesters). The modifier-rich phase may be characterized by the presence of a new a peak (Fig. 11.10). But on occasions there may be superposition of peaks and the presence of the modifier cannot be easily detected by these techniques. If part of the added polymer is soluble in the thermoset matrix, its eventual plasticizing effect can be determined from the corresponding matrix Tg depletion, and the... 

Fig. 6.1.3. Solid HETCOR spectrum of poly(2,6-dimethyl-/7-phenylene oxide). Note that the CRAMPS spectrum for protons in this sample, shown on the left axis, is a superposition of peaks belonging to different carbon species, as indicated by the 2D separation on the horizontal axis [29].

To simulate the valence XPS, we started with a superposition of peaks centered on each VIP. As described previously [6], each peak is represented by a Gaussian-line-shaped curve. In the case of the line width ( WH(k)), we used WH(k)=0.l0 h (proportional to the ionization energy) for valence XPS. 

O to O by a vector OO = r. Therefore, the Patterson function will be large if the strong regions of electron density are separated by the vector r and if there are several strong regions of electron density separated by a vector r, the P(r) will show a total effect of it and will also be large. The Patterson function will be a superposition of peaks derived from all pairs of atoms in the unit cell. If there is no overlap of Patterson peaks, then the function P(r) will show the position of all interatomic vectors but usually the resolution of Patterson function is very poor and in fact the Patterson peaks are more diffuse than the electron density peaks. Despite this overcrowded nature of the Patterson maps, useful information can be derived and complex structures can be solved from an interpretation of Patterson function. 

There is a small peak one mass unit higher than M m the mass spectrum of ben zene What is the origin of this peak d What we see m Figure 13 40 as a single mass spectrum is actually a superposition of the spectra of three isotopically distinct benzenes Most of the benzene molecules contain only and H and have a molecular mass of 78 Smaller proportions of benzene molecules contain m place of one of the atoms or m place of one of the protons Both these species have a molecular mass of 79... 

IR spectroscopy is an inherently faster method than NMR and an IR spectrum is a superposition of the spectra of the various conformations rather than an average of them When 1 2 dichloroethane is cooled below its freezing point the crystalline matenal gives an IR spectrum consistent with a single species that has a center of symmetry At room temperature the IR spec trum of liquid 1 2 dichloroethane retains the peaks present in the solid but includes new peaks as well Explain these observations... 

This capacitor experiences the same current waveform at the power switch, which is a trapezoid with an initial current of about 1A rising to 2.8 A with very sharp edges. This capacitor has much more rigorous operating conditions than the output filter capacitor. I will estimate the RMS value of the trapezoidal current waveform as a piecewise superposition of two waveforms, a rectangular 1A peak waveform and a triangular waveform with a 1.8 A peak. This yields an estimated RMS value of 1.1 A. The value of the capacitor is then calculated as ... 

This compound has two crystallographically distinct vanadium sites. While the static spectrum is a superposition of two powder patterns of the kind shown in Figure 3, MAS leads to well-resolved sharp resonances. Weak peaks denoted by asterisks are spinning sidebands due to the quadrupolar interaction. 

Figure 15-3 shows the optical absorption spectrum of a MEH-PPV/C60 film with different C, content compared to the optical absorption spectrum of the components alone. The peak at 2.5 eV is identified as the n-n absorption of MEH-PPV and is clearly observed along with the first dipole-allowed transition in C(l0 (at 3.75 eV). The spectrum is a simple superposition of the two components. Further-... 

Fig. 31 Evolution of the Raman spectra of a high-pressure and photo-induced sample of Se while decreasing the pressure at ca. 300 K [109]. The spectrum at 3.9 GPa shows the onset of the transformation S6 p-S. The asterisks indicate the Raman signals typical for p-S whereas the peaks of two stretching vibrations of p-S coincide with those of Se at about 458 cm and 471 cm (not indicated by asterisks). The Raman spectrum of the sample recovered at ambient pressure (0 GPa) is evidently a superposition of the spectra of a-Sg and polymeric sulfur, Sj, arrows indicate plasma lines of the Ar ion laser at 515 nm, which have been used for calibration). For Raman spectra under increasing pressure, see Fig. 23 in [1] and references cited therein...

Two-dimensional relayed NOESY experiments (Wagner, 1984 Kessler et al., 1988) give cross-peaks that could be a superposition of nOe s resulting from different relay nuclei. This complicates the extracting of crossrelaxation rates. The 1D NOESY experiment (Kessler et al., 1989a), however, allows the path of the magnetization transfer to be clarified. 

Figure 31 Superposition of the 10-ppm HMBC spectrum (filled black peaks) with the 9.9-ppm HMBC spectrum (dotted grey contours) of Cyclosporine A. In the 9.9-ppm spectrum, the chemical shifts are shifted in a quantized manner relative to the signals in the 10-ppm spectrum according to the first two digits of the high-order chemical shift. The two insets show the actual difference A<5 between the cross-peaks in the two spectra for the H-C(e) and the CH3N resonances of MeBmt 1.

H2 TPR measurements are used to probe the reducibility and may reveal more information on the nature of vanadium and molybdenum species. The assignment of the TPR peaks has been based on the literature study [9, 10] but also by using two reference samples V1-Z15 and Mol-Z15 prepared by solid-state ion exchange. TPR thermograms of V-Mo-Zeolite systems can be divided into two zones of H2 consumption (/) Mo-Zeolites exhibit two reduction peaks at 600 and 850°C corresponding to the reduction of Mo6+ into Mo4+ through the Mo5+ step and to the reduction of Mo4+ into Mo°, respectively while (ii) V-Zeolites led to a broad asymmetric feature around 710°C, which has been previously attributed to the reduction of V5+ into V3+. Finally, the TPR profiles of V-Mo-Zeolite catalysts seem more like a superposition of both Mo and V-catalysts TPR profiles. 

Figure 7.15 Superposition of the ESI mass spectrograms of the [Ce2], [Er2] and [CeEr] complexes, emphasizing the absence of the characteristic peaks from any of the homometallic analogues on the graph from the heterometallic species.

Figure 3.21 UPS spectrum of Xe physisorbed on Ru(OOl) showing the superposition of the Xe 5p levels with the d-band of Ruthenium. The position of the Xe 5pm peak with respect to the Fermi level of Ru is a measure of the work function of the adsorption site, as the potential diagram indicates (from Wandelt et al. L54J).

The entire cyclic voltammogram is no longer reversible according to the definition we have attached to this term so far. In other words, the symmetry and translation operations as in Figures 1.4 and 6.1 do no longer allow the superposition of the reverse and forward trace. It also appears that the midpoint between the anodic and cathodic peak potentials does not exactly coincide with the standard potential. The gap between the two potentials increases with the extent of the ohmic drop as illustrated in Figure 6.2 for typical conditions, which thus provides an estimate of the error that would result if the two potentials were regarded as equal. 

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