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Line shapes, temperature-dependent

The temperature-independent component of the line shape, which depends on spin density, is predominantly due to variations in the g-values at different paramagnetic sites and to dipolar interactions between spins (Voget-Grote et al, 1976 Thomas et al, 1978). Estimates of the dipolar contribution, which yield a Lorentzian line shape for dilute spin concentrations (< 10 cm ), can be obtained from Eq. (10) of Section 1 a in which y is the gyromagnetic ratio of the electron and n = Ns is the concentration of paramagnetic spins. For Ns 10 Thomas et al (1978) calculate a 5G, which is consistent with what is commonly observed for the temperature-independent component of a. [Pg.130]

For a sample at diennal equilibrium there is a distribution of speeds which depends on the mass of the molecules and on the temperature according to the Boltzmaim distribution. This results in a line shape of the form... [Pg.1144]

Geva E and Skinner J L 1998 Optical line shapes of single molecules in glasses temperature and scan-time dependence J. Phys. Chem 109 4920-6... [Pg.2507]

The shape of the equilibrium line, or solubility curve, is important in determining the mode of crystallization to be employed in order to crystallize a particular substance. If the curve is steep, i.e. the substance exhibits a strong temperature dependence of solubility (e.g. many salts and organic substances), then a cooling crystallization might be suitable. But if the metastable zone is wide (e.g. sucrose solutions), addition of seed crystal might be necessary. This can be desirable, particularly if a uniformly sized product is required. If on the other hand, the equilibrium line is relatively flat (e.g. for aqueous common salt... [Pg.61]

Simulation programs for the ESR line shapes of peroxy radicals for specific models of dynamics have been developed for the study of oxidative degradation of polymers due to ionizing radiation [66]. The motional mechanism of the peroxy radicals, ROO, was deduced by simulation of the temperature dependence of the spectra, and a correlation between dynamics and reactivity has been established. In general, peroxy radicals at the chain ends are less stable and more reactive. This approach has been extended to protiated polymers, for instance polyethylene and polypropylene (PP) [67],... [Pg.514]

In the practice of solid-state bioEPR, a Lorentzian line shape will be observed at relatively high temperatures and its width as a function of temperature can be used to deduce relaxation rates, while a Gaussian line will be observed at relatively low temperatures and its linewidth contains information on the distributed nature of the system. What exactly is high and low temperature, of course, depends on the system for the example of low-spin cytochrome a in Figure 4.2, a Lorentzian line will be observed at T = 80°C, and a Gaussian line will be found at T 20°C, while at T 50°C a mixture (a convolution) of the two distributions will be detected. [Pg.60]

The second issue of interest is the temperature dependence of elastic tunneling spectroscopy. Because the bands are intrinsically wide, spectra measure at 5 K are similar in line shape to those measured near 300 K. In any case, the integrated normalized intensities,... [Pg.208]

The temperature dependent spectra of PBLG-d5 is shown in Fig. 6. Line shapes below — 76°C are similar to the rigid state pattern, indicating the absence of fast and large-amplitude motions. They are, however, different in... [Pg.306]

The r-dependence of the spectra of PBLG- d2 is shown in Fig. 17. An increase in the pulse spacing r leads to a reduction of the spectral intensity and characteristic line shape changes. The remarkable r-dependence is observed around 40-60°C for both samples. These results show the presence of motions with rates as high as the QCC at the k and positions in this temperature region, and are consistent with the remarkable signal intensity loss around 50°C. [Pg.313]

The temperature dependent 7j for both samples was calculated by the three-site jump model with the parameters derived from the line shape and the result is shown in Fig. 18. The calculated 7j values for both samples are in good agreement with the experimental ones around the minimum, showing the validity of the parameters concerning with the jump rates and polar... [Pg.319]

T reveal that the reorientation of the phenyl ring is restricted, but that most of the phenyl rings undergo the flipping motion even in the stacked state. This agrees with the result of the temperature dependence of the line shapes and 13C CP/MAS measurements.76... [Pg.327]

The temperature dependent line-shapes of racemic PBG-Ah are shown in Fig. 30, together with those of PBLG- d2. The line shape at room temperature... [Pg.327]

The temperature dependent line shape of racemic PBG-yd2 is shown in Fig. 34 together with those of PBLG-yd2. The line shapes at room temperature appear to be the rigid state powder pattern, showing the absence of the large amplitude motion in the y position. The signal intensity of the... [Pg.332]

For the g2SC phase, the typical results for the default choice of parameters H = 400 MeV and r/ = 0.75 are shown in Figure 4. Both the values of the diquark gap (solid line) and the mismatch parameter 5/j, = /i,./2 (dashed line) are plotted. One very unusual property of the shown temperature dependence of the gap is a nonmonotonic behavior. Only at sufficiently high temperatures, the gap is a decreasing function. In the low temperature region, T < 10 MeV, however, it increases with temperature. For comparison, in the same figure, the diquark gap in the model with /je = 0 and /./, = 0 is also shown (dash-dotted line). This latter has the standard BCS shape. [Pg.232]

In a recent experimental study involving the temperature dependences of the IR and Raman line shapes, Loparo et al. [14] confirmed that non-Condon effects are important in experimental (and theoretical ) line shapes, and they found a frequency dependence to the dipole derivative that is qualitatively similar to the form used in our work. [Pg.79]


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