Hydride ions are excellent candidates for probing the electronic structure of BTOH with solid-state NMR, since they are directly bonded to the Ti ions, which host the localized electron polarons or conduction electrons in the 3d-band. Usually the most abundant hydrogen isotope 1 H is studied by NMR, however, resonances of surface-adsorbed water and/or hydroxyl groups overlap with the hydride signals complicating the quantitative and qualitative analysis of the spectra (see Fig. ). The interfering background signals can be removed by isotopic substitution of 1 H with deuterium 2 H in the material (see Fig. ). Furthermore, 2 H exhibits a nuclear electric quadrupole moment that, coupled with the electric-field gradient, gives rise to the quadrupolar interaction, which is very receptive to changes in the local geometry, and gives a lineshape that is sensitive both to the structure and dynamic processes on the ms-µs timescale. The disadvantage of 2 H is the reduced sensitivity due to the lower gyromagnetic ratio.