Fig. 3: Nanoconfinement effect on water.
From: Interfaces govern the structure of angstrom-scale confined water solutions
a, b Experimental \({{\mbox{Im}}}{\chi }_{{yyz}}^{(2)}\) spectra of water within extreme confinement in the (a) CaF2-graphene and (b) SiO2-graphene capillaries at varying relative humidities. The sum of the water/graphene and SiO2/water signals is shown in (b) for comparison. In (a), the water thickness is determined from the AFM height profiles, assuming a graphene thickness of 3.3 Å. The dashed grey lines in (a) and (b) serves as zero lines. The dashed arrows indicate the blueshift of the strongly H-bonded response, indicative of a weakening of the H-bonds. Note that the net orientation of water remains reversed between the two systems, even for the strongest confinement—with negative and positive \({{\mbox{Im}}}{\chi }_{{yyz}}^{(2)}\), for CaF2-graphene and SiO2-graphene capillaries, respectively. Data in (a) were obtained from two independent samples per RH condition. Data in (b) were obtained from a single sample measured under different RH conditions. Source data are provided as a Source Data file.
