中文摘要：

研究受限于纳米尺度空间的水或者其他分子液体的性质在生物学、材料科学、摩擦学、微流控等领域有重要的意义。但直接通过显微镜观察界面上的纳米尺度液体的润湿动态过程仍然是个挑战。近年来受益于石墨烯等二维晶体材料的发现与发展，由石墨烯作为覆盖材料形成的受限体系为这一问题提供了很好的解决方式。通过原子力显微镜原位成像发现，由石墨烯与云母组成的受限体系中包含水层，一层水层的高度约为0．37nm，而通过改变周围空气的湿度可以调控受限体系中水层的湿润-去湿润可逆性变化。同时实验中观察到了水层随湿度变化时呈现出的不同的生长方式。平整的石墨烯覆盖层提供了一种新的尺寸可调整的纳米通道，可对纳米尺度的受限水层实现高分辨成像，为纳米流体器件的发展提供了可能性。

英文摘要：

Background： The nature of confined water adlayer at nanoscale under ambient is important in biology, material science, and nanofluidics. However, observing wetting and dewetting process of water adlayer on the interface directly is still a challenge. Purpose： This paper aims to reveal the nature of confined molecularly thin water layer between a graphene layer and a mica substrate. Methods： Room temperature in-situ Atomic Force Microscope （AFM） observation method was adopted here. Results： The results showed that the measured height of the monolayer water film was about 0.37 nm, in agreement with the height of a monolayer of ice. The wetting and dewetting process of water adlayers was able to be controlled by changing the ambient humidity. The molecularly thin adlayers can wet the interface through increasing the humidity; otherwise it dewets by reducing the humidity. Conclusion： The flat graphene coating offers a novel size-adjustable nano channel, which suggests a new approach for high resolution imaging of confined molecularly thin fluid films. Furthermore, these results can potentially aid in the fabrication of novel nanofluidic devices.