Line shape analysis magnetic parameters

The main advantage of a multi-frequency study is that it provides information on the frequency dispersion of magnetic resonance parameters. This approach (dispersion), for example, is the power in NMRD studies. Several laboratories pioneered in the application of multi-frequency EPR as a route to a more accurate evaluation of key spectroscopic parameters (g, A, Q, D, E), as well as a more sensitive methodology for studying dynamical processes, where an interplay between the frequency dependence of the spin process and the frequency dependence of the EPR observation often can provide exceptionally detailed information [64,65]. In order to take advantage of the method, the frequency dependence of spin systems must be understood. This has led to the development of several theoretical approaches for better analysis of multi-frequency data, and especially in BPCA research, for the analysis of the frequency dependence of geffective, Tle, T2e, and the overall EPR line shape in frozen glasses and in room-temperature aqueous solutions. 

Fig. 8.5. Solid-state N NMR spectra obtained from the oriented [ N]Gly silk fibroin fiber sample. Spectra were observed with the fiber axis both (A) parallel and (B) perpendicular to the magnetic field. The best-fit simulated line shapes are superimposed on the experimental spectra. Parameters for spectral simulation were found from error analysis as a function of ap and Pf(C).

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