Spin-lattice relaxation rate constant

K. W. Rousslang and A. L. Kwiram, Triplet state decay and spin-lattice relaxation rate constants in tyrosinate and tryptophan, Chem. Phys. Lett. 39, 226-230 (1976). 

The convenient NMR observables depend on the characteristics of the system studied, but generally the protons of the liquid are readily detected. The apparent NMR linewidths are often determined by the magnetic susceptibility inhomogeneities in the sample and do not directly reflect the dynamics of the liquid. This report will focus largely on theoretical approaches to understand the spin-lattice relaxation rate constants for both classes of microporous materials. The magnetic held dependence of the spin-lattice relaxation rate constant generally provides a useful dynamical characterization of the liquid and often a structural characterization of the confining media. 

The only protein for which measurements of the individual triplet sublevel decay constants and spin-lattice relaxation rate constants have been measured is lysoz5une, and these only for the major emitting tryptophan sites (narrow-band optical detection at 415 nm). Measure-... 

Here, K% is a constant related to the NMR coupling constant,. S 2 is the spectral density associated with the second-rank orientational correlation function g2(f). If g2(f) is an exponential function, such as in rotational diffusion, Eq. (16) reduces to the famous Bloembergen-Purcell-Pound (BPP) expression for the spin-lattice relaxation rate [81,82]. 

To conclude, the ratio coq/Ti may be considered, in most cases, as a homogeneous function with respect to the product of the Larmor fequency and one characteristic molecular time constant this property is very useful to disclose relative variations of this time constant as a function of temperature or concentration. The coincidence of maximum values of the (Hq/Ti ratio with one another, indicates that the mean square dipole-dipole interaction is hardly dependent on temperature or polymer concentration. It is worth noting that spin-lattice relaxation rates are foxmd to be insensitive to chedn length variations tmless molecular weights become lower than about 10,000 g/moL. 

Determination of ET rate constants. The proton relaxation of the cyclopentadienyl (cp) ring of the present mixed-valence complex is caused by the magnetic dipolar interaction with the electron spin on the Fe(III) ion of the fetiicenium unit (S=l/2). Then the proton spin-lattice relaxation rate of bfc+, 1/Ti, is represented by ... 

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