Freeze-drying FT-IR/ATR spectroscopy has been proposed as a method for hydration studies of biologically important molecules in two previous papers. The procedure consists in the freeze-drying of the dilute aqueous solution of a compound directly on the ATR crystal and running the FT-IR spectrum after the removal of ice by sublimation. In this method the hydrated ATR crystal surface is used as a substrate for the adsorbed molecules. Consequently, the degree of hydration of the adsorbed molecules depends on the extent of the water coverage of the crystal surface. In our previous studies, the spectra of heavily hydrated species have been studied. Information about the binding preferences of water molecules to the different hydrophilic sites of some mononucleotide molecules has been obtained.
Simona Băkdilescu and Camille Sandorfy, "Freeze-Drying Fourier Transform Infrared Attenuated Total Reflection Spectroscopy of Surface Adsorbed Layers: Hydration of Cytidine-5'-Phosphoric Acid at Controlled Relative Humidity," Appl. Spectrosc. 40, 1236-1239 (1986)