An intriguing unknown variant of the nematic liquid-crystal phase (Nx) has been discovered first in a class of main-chain polymers, and later in LC dimers connected via an alkylene spacer. A well-defined first order transition separates the high-temperature N phase from the low-T Nx. It has recently been recognised that the Nx phase exhibits one of the fastest linear switching modes in any LC. The nature of the Nx phase is poorly understood. The diffuse X-ray scattering shows change at the transition, but the contribution of mesogen, spacers and end-tails cannot be resolved. We propose to carry out neutron scattering on magnetically aligned LC dimers with perdeuterated alkylene spacers to separate the scatter of the spacer and mesogen in thetwo N phases.