  Using a novel Se-labelled dimer mixed with DTC5C7 aligned by magnetic field,
the twist-bend nematic phase (Ntb) in dimers was studied by hard X-ray resonant
scattering and by small and wide angle X-ray scattering (SAXS, WAXS). Resonant
diffraction spots indicated a helix with a 9-12 nm pitch in the Ntb phase.
Unprecedentedly high helix orien-tation enabled deconvolution of global and
local order parameters. This, combined with simultaneous resonant and
non-resonant SAXS and WAXS data, allowed us to construct a modified model of
the Ntb phase matching twisted molecular conformations and the local
heliconical director field.
