Nuclear relaxation rates applications

It is important to point out that this does not imply that Markovian stochastic equations cannot be used in descriptions of condensed phase molecular processes. On the contrary, such equations are often applied successfully. The recipe for a successful application is to be aware of what can and what cannot be described with such approach. Recall that stochastic dynamics emerge when seeking coarsegrained or reduced descriptions of physical processes. The message from the timescales comparison made above is that Markovian descriptions are valid for molecular processes that are slow relative to environmental relaxation rates. Thus, with Markovian equations of motion we cannot describe molecular nuclear motions in detail, because vibrational periods (10 " s) are short relative to environmental relaxation rates, but we should be able to describe vibrational relaxation processes that are often much slower, as is shown in Section 8.3.3. 

A preliminary report (Amato et al. 1998) presents ZF- and LF-pSR data down to 0.1K. The ZF spectra are characterized by nuclear-electronic double relaxation. The nuclear part can be suppressed in LF = 20 G. No magnetic transition was observed. Below 10 K, the electronic relaxation rate increases monotonically with decreasing temperature. Application of LF = 200 G also suppresses electronic relaxation, indicating rather slow dynamics of the spin system. From the field dependence of relaxation rate the spin fluctuation frequency was found to be V4f(r —> 0) 2.7 MHz. It appears that this is another case where spin correlations develop at low temperatures, but persistent slow spin dynamics prevent the formation of an ordered magnetic state (see CeNiSn in sect. 9.2 for comparison). 

Application of Nuclear Magnetic Resonance to Investigations of Drug-Receptor Interactions - The application of nuclear magnetic resonance spectroscopy to the study of interactions between small molecules and macromolecules has increased appreciably in the past five years. The technique of following the change effected in the relaxation rates of the protons of a small molecule by binding to a macromolecule has now been applied to the study of enzyme-substrate interactions, enzyme-inhibitor interactions, and enzyme-coenzyme inter... 

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