The hydrogen bond represents an important interaction between molecules and the dynamics of
hydrogen bonds in water create an ever-present question associated with the process of chemical
and biological reactions. In spite of numerous studies the process remains poorly understood
at the microscopic level because hydrogen-bond dynamics such as bond rearrangements and
hydrogen proton transfer reactions are extremely difficult to probe. Those studies have been
carried out by means of spectroscopic methods where the signal stems from the ensemble of a
system and the hydrogen-bond dynamics were inferred indirectly. This book addresses the direct
imaging of hydrogen-bond dynamics within water-based model systems assembled on a metal surface
using a scanning tunneling microscope (STM). The dynamics of individual hydrogen bonds in water
clusters hydroxyl clusters and water-hydroxyl complexes are investigated in conjunction with
density functional theory. In these model systems quantum dynamics of hydrogen bonds such as
tunneling and zero-point nuclear motion are observed in real space. Most notably hydrogen
atom relay reactions which are frequently invoked across many fields of chemistry are
visualized and controlled by STM. This work presents a means of studying hydrogen-bond dynamics
at the single-molecule level providing an important contribution to wide fields beyond surface
chemistry.
