Study of a nanoscale water cluster by atomic force microscopy.

We present a novel method for investigating a nanometric cluster of water molecules, which includes the formation and manipulation of nanometric water, and the measurement of its mechanical properties. The atomic force microscope based on the quartz tuning-fork sensor is employed to form and manipulate the nanometric water, and the theoretical tool of amplitude-modulation atomic force microscopy is used to obtain the elasticity, viscosity and dissipation energy of it. With high vertical resolution less than approximately 0.1 nm and high force sensitivity of approximately 0.01 N m(-1), this tool facilitates the stable formation and manipulation of a nano-water cluster (approximately 10(4) molecules) in air without 'jump-to-contact' instability, as well as quantitative measurements of its physico-chemical properties. PACS numbers: 47.55.nk, 62.10.+s, 68.37.Ps