Skip to main content
. 2020 Jul 24;6(30):eaaz9708. doi: 10.1126/sciadv.aaz9708

Fig. 4. AM-AFM reveals multilayered water films on gibbsite under the condensation regime.

Fig. 4

(A) AFM image sequence of gibbsite under humidified Ar(g) at 30°C (solid yellow frame), 10°C (blue frame), and 4°C (purple frame) and reheated to 30°C (dashed yellow frame). Imaging under dry Ar(g) confirmed that the gibbsite particle was ~10 nm thick. (B) Corresponding topographical cross sections. A step edge meniscus was observed at 4°C. Amplitude curves on (C) gibbsite and (D) bare gold under approach (solid lines) and retraction (dashed lines). (E) Jump distances during approach and retract on gibbsite and gold as a function of temperature. Hysteresis was observed, with jump-from-contact during retraction occurring at a greater distance than the jump-to-contact on approach. An increase in apparent particle thickness and the jump-to-contact distance at 4°C (δ ~ 2.5 nm) reveal the formation of ~9 water monolayers. Comparison of force-distance profiles confirmed that thick water films were formed on gibbsite, but not gold. Reversibility was observed in the gibbsite height (A and B) and in the tip approach/retract distances [(C) and table S1] after reheating the sample back to 30°C.