NDIS measurements were conducted at 23 The collected data were corrected for multiple scattering and absorption effects and normalized to a standard vanadium scatterer. The total correlation between non-exchangeable hydrogen atoms on TMA and other atomic species in the system can be obtained via the first order difference functions, ∆S X,D 2 O H TMA (Q) and ∆S X,H 2 O H TMA (Q) (Fig. ; Eqs. ( ) and ( )). These functions essentially represent a weighted sum of the contributions from the structural correlations involving the H/D atoms of TMA. They are respectively defined as (in units of mbarns).