Polarized line shapes

Fig. 8. Comparison between experimental and simulated ( H)- C cross-polarization line shapes for immobilized (top) and dispersed cetyl palmitate nanospheres (bottom). The calculations are based on the chemical shift data for n-eicosane and polyethylene terephthalate which explains for the deviation of some resonance positions.

As we have already mentioned, CDCI3 should be avoided as a solvent for salts for two reasons. Firstly, salts are unlikely to be particularly soluble in this relatively nonpolar solvent but more importantly, spectral line shape is likely to be poor on account of relatively slow proton exchange at the protonatable centre. The remedy is simple enough - avoid using CDCI3 and opt for one of the more polar options instead, e.g., deuterated DMSO or MeOH and you should obtain spectra every bit as sharp as those of free bases. 

Figure 9.9 Simulated normalized line shapes of -polarized (a-c) and p-polarized (if-/) second-harmonic signals for quarter waveplate measurements (a) and (if) hypothetical achiral surface (hs = 0.5 fp = 0.75, gp = —0.5), (b) and (if) hypothetical chiral surface with in-phase chiral coefficient (fs = 0.75, hs = 0.5 fp = 0.75, gp = —0.5, hp = 0.25), (c) and (/) hypothetical chiral surface with out-of-phase chiral coefficient ( fs = 0.75 0.25i, hs = 0.5 fp = 0.75, gp = —0.5, hp = 0.25z). Upper (solid line) and lower (dashed line) sign in expansion coefficients correspond to two enantiomers. Rotation angles of 45° and 225° (135° and 315°) correspond to right-hand (left-hand) circularly polarized light and are indicated for one of enantiomers with open and filled circles, respectively.

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... 

We begin by considering the absorption line shape for a liquid. If the light is polarized along lab-fixed axis p, the line shape is given by the Fourier transform... 

From a theoretical perspective, since the designation of the lab-fixed axes is arbitrary, what is relevant is the relative orientation of the polarizations of the excitation and scattered light. Thus the line shape for excitation light polarized along axis p, and scattered light polarized along axis q (p or q denote X, Y, or Z axes in the lab frame) is called Ipq(co). When p = q this is lyy, and when p q this is IVH. Mixed quantum/classical formulae for Ipq(co) are identical to those for the IR spectmm, except mPi is replaced by apqP which is the pq tensor element of the transition polarizability for chromophore i. Thus we have, for example [6],... 

In addition to structural information, Li MAS NMR Tz relaxation measurements and analysis of Li line shapes have been used to probe the dynamics of the lithium ions. Holland et al. identified two different species with different mobilities (interfacial Li (longer Tz, rapid dynamics) and intercalated lithium (shorter Tz, slower dynamics)) in the elec-trochemically lithiated V2O5 xerogel matrix. Li hopping frequencies were extracted from an analysis of the Li line widths and the appearance of a quadru-polar splitting as the temperature decreased in a related system. ... 

Analytical expressions were derived for the CW EPR line-shape for spin-polarized radical pairs in the limit where the combined dipolar and exchange interaction is weak relative to the energy differences between the resonances of the two spins.19 The equations were applied to the case of charge-separated sites in Ti02 nanoparticles. This approach simplifies the analysis of the distributions of interspin distances. 

Now we turn to the measurements in zz polarization configuration. For our crystal two lines of Aig symmetry at 232 and 448 cm"1 are observed at room temperature as shown in Fig. 3. The disadvantage of the Sr-doped La2Ni04 system is that the dopant positions are fixed at relatively high temperature and may be random. At room temperature we do not see any dopant-induced extra features in the low frequency part of the spectra. The line shape of the Ni-0(2) bond stretching mode at 448 cm 1 is asymmetric. This asymmetry can be explained by a random distribution of holes on oxygen above Tco. 

I, must be deconvoluted from the laser line shapes the Raman resonance line shapes the detector slit function and the polarization properties of the laser and signal fields. 

This section, considers the line shapes of O—H and O—D crystalline glutaric acid, as measured by Flakus and Miros [112], at room (298 K) and liquid nitrogen (77 K) temperatures, as well as with two different polarizations By using the IR beam of normal incidence with respect to the crystalline ac plane, the polarized spectra were measured by these authors for two orientations of the electric held vector E parallel (Pol = 0°) and perpendicular (Pol = 90°) to the c axis. Comparison is made between the experiment (grayed spectra) and theory (thick line). 

To perform the VES calculations it is necessary to consider a finite duration pulse, which has a finite bandwidth. In addition, the actual shape of the vibrational echo spectrum depends on the bandwidth of the laser pulse and the spectroscopic line shape. Several species with different concentrations, transition dipole moments, line shapes, and homogeneous dephasing times can contribute to the signal. Therefore, VES calculations require determination of the nonlinear polarization using procedures that can accommodate these properties of real systems. 

Ruhman S, Nelson KA. Temperature-dependent molecular dynamics of liquid carbon disulphide polarization-sensitive impulsive stimulated light-scattering data and Kubo line shape analysis. J Chem Phys 1991 94 859-867. 

Key Words Dipolar glasses, Ferroelectric relaxors, Conducting polymers, NMR line shape, Disorder, Local polarization related to the line shape, Symmetric/asymmetric quadrupole-perturbed NMR, H-bonded systems, Spin-lattice relaxation, Edwards-Anderson order parameter, Dimensionality of conduction, Proton, Deuteron tunnelling. 

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