Fig. 2. Temperature-dependent OD-stretch SFG spectra collected in the ssp polarization combination, along with fits.

For clarity, the 10 °C and 5 °C spectra are offset from the corresponding 20 °C spectrum by 0.01 and 0.02 arbitrary units, respectively. A Spectra of water molecules interacting with the ice-nucleating active protein InaZ9R in D₂O-based PBS buffer. The intensity of the water signal is increased significantly for lower temperatures in the presence of inaZ9R. B Spectra of the neat buffer surfaces remain essentially unchanged. C Plot of the SFG amplitudes for the different water modes fitted to the InaZ9R spectra.