  The NMR spectra of spin-1/2 pairs contains four peaks, with two inner peaks
much stronger than the outer peaks in the near-equivalence regime. We have
observed that the strong inner peaks have significantly different linewidths,
when measurements were performed on a 13C2-labelled triyne derivative. This
linewidth difference may be attributed to strong cross-correlation effects. We
develop the theory of cross-correlated relaxation in the case of
near-equivalent homonuclear spin-1/2 pairs, in the case of a molecule
exhibiting strongly anisotropic rotational diffusion. Good agreement is found
with the experimental NMR lineshapes.
