All spectroscopic measurements were performed in transmission geometry on self-supporting zeolite pellets of 70-150 μm thickness prepared from 7-15 mg of powdered sample held at 1 ton for 1 minute in a pellet press (Specac). Pellets were held in a heated spectroscopy cell with gas-flow capability (Linkam FTIR600) and sample temperature controlled by the sample being in direct contact with a cell heater block held between (but not in contact with) two CaF2 windows. A centrally located 4mm hole in the heater block allowed passage of light through the pellet. For a given heater block temperature setpoint, the free-standing portion of the zeolite had a static thermal gradient, with the sample coolest in the middle (farthest from the heater block). This gradient was measured by thermal imaging of the sample. Measurements were carried out at 1 atmosphere under flowing N2 (liquid N2 boil-off) with sample hydration and deuteration achieved by sparging controlled flows of N2 through a Drechsel flask containing a 20% solution of D2O in H2O (referred to as HOD/H2O below for brevity). A schematic of the gas flow apparatus is shown in the supplementary information (ESI) Section 1. FT-IR spectra were collected using a Bruker Tensor spectrometer operated at 4 cm -1 spectral resolution.