The use of deuteration to overcome the difficulties associated with the incoherent scattering from hydrogen, is a well established technique. However, there are increasing questions being asked about the significance to the physics both of swapping deuterium for hydrogen, and the degree of substitution. In previous LET experiments we have observed flat modes, in addition to the dispersive features, that we have successfully modelled. It has been suggested that these flat inelastic modes may be associated with clusters created by hydrogen defects in our samples. In order to attempt to prove or disprove this scenario, we propose to measure purposefully partially deuterated samples, in an attempt to reproduce these features, and to investigate the energy dependence of them.