Koerber, Thomas published the artcileSystematic differences in the relaxation stretching of polar molecular liquids probed by dielectric vs magnetic resonance and photon correlation spectroscopy, Product Details of C18H19Cl2NO4, the main research area is relaxation stretching polar liquid NMR dielec photon correlation spectroscopy.
Relaxation spectra of mol. glass formers devoid of secondary relaxation maxima, as measured by dielec. spectroscopy (DS), NMR relaxometry, photon correlation spectroscopy (PCS), and Fabry-Perot interferometry, are quant. compared in terms of the Kohlrausch stretching parameter βK. For a reliable estimate of βK, the excess wing contribution has to be included in the spectral anal. The relaxation stretching probed by PCS and NMR varies only weakly among the liquids (βK = 0.58 ± 0.06). It is similar to that found in DS, provided that the liquid is sufficiently nonpolar (relaxation strength Δε≲6). For larger strengths, larger βDSK (narrowed relaxation spectra) are found when compared to those reported from NMR and PCS. Frequency-temperature superposition (FTS) holds for PCS and NMR. This is demonstrated by data scaling and, for the few glass formers for which results are available, by the equivalence of the susceptibilities χ′′PCS(ωτ) ∼ χ′′NMR(τ) ∼ χ′′NMR(ω), i.e., measuring at a constant frequency is equivalent to measuring at a constant temperature or constant correlation time. In this context, a plot of the spin-lattice relaxation rate R1(T) as a function of the spin-spin relaxation rate R2(T) is suggested to reveal the stretching parameter without the need to perform frequency-dependent investigations. Dielec., we identify a trend of increasing deviations from FTS with increasing Δε. Depending on the technique and glass former, the relative relaxation strength of the excess wing varies, whereas its exponent appears to be method independent for a given substance. For polar liquids, we discuss possible reasons for the discrepancy between the results from PCS and NMR as compared to those from DS.
Journal of Chemical Physics published new progress about Dielectric loss. 72509-76-3 belongs to class pyridine-derivatives, name is 3-Ethyl 5-methyl 4-(2,3-dichlorophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate, and the molecular formula is C18H19Cl2NO4, Product Details of C18H19Cl2NO4.