Generalized relaxation cross

Bonamy L., Bonamy J., Robert D., Temkin S. I. Consequences of angular momenta coupling on generalized spectroscopic relaxation cross-sections collisional narrowing in isotropic and anisotropic Raman CO2 branches, Proc. 13th ICORS. (Wiley Sons, New York) (1992). 

To understand how the CP/MAS experiment can be applied to quantitative analysis, the magnetization transfer and relaxation processes, which directly affect the signal intensity, must be considered. Cross polarization is mediated by H-13C dipolar interactions, so the magnetization buildup will occur at different rates for different types of carbons. In general, the cross polarization rate (Tcp1) increases with the degree of protonation.21 22 That is, TcP is generally shorter for methylene and methine carbons than for quaternary carbons, Fig. 12.6. Motional modulation... 

An excellent review text has recently been published by Tycko outlining various experimental NMR approaches to molecular dynamics, both in small and macromolecules [85]. In terms of the application of these various methods to polymers, one can generally categorize the techniques as direct (e.g., 2D exchange, labeling and lineshape analysis) or indirect (e.g., relaxation, cross-relaxation) probes of molecular dynamics, and additionally, rank them in terms of whether they probe a specific, local type of motion or longer range, correlated chain dynamics. Finally, solid-state NMR... 

An alternative mechanism of excess energy release when electron relaxation occurs is through x-ray fluorescence. In fact, x-ray fluorescence favorably competes with Auger electron emission for atoms with large atomic numbers. Figure 16 shows a plot of the relative yields of these two processes as a function of atomic number for atoms with initial K level holes. The cross-over point between the two processes generally occurs at an atomic number of 30. Thus, aes has much greater sensitivity to low Z elements than x-ray fluorescence. 

---