Residual dipolar couplings of soft solids by accordion magic sandwich

Residual dipolar coupling are important source of information about structure and molecular motions of soft solids. A new method, accordion magic sandwich is introduced, to measure these couplings in terms of residual van Vleck moments. A magic sandwich of variable duration leads to a Hahn echo which samples the shape of the magic echo. In this way residual dipolar couplings can be determined model free without contribution of inhomogeneous spin interactions and transverse magnetization relaxation. The method was tested on adamantane and on series of samples from cross-linked natural rubber.