Spin-Lattice Relaxation of a Rouse Chain

For the treatment of spin-lattice relaxation, we need an expression for the autocorrelation function of the Kuhn segment tangent vector, which in the continuum limit is given by 

The autocorrelation function of this vector is readily found as an expression based on the autocorrelation function of the normal coordinates, Eq. 55, 

According to Refs. [47-49], the spin-lattice relaxation rate is related to the tangent vector autocorrelation function by 

This expression is based on a variant of Eq. 28 especially suited for the description of chain modes [47]. Inserting Eq. 62 we find the limits 

The logarithmic frequency dependence [50, 51] in the limit ffl Tj Vill be of particular interest for experimental tests of the model. 

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