Signatures of Quantum-Tunneling Diffusion of Hydrogen Atoms on Water Ice at 10 K.

Title Signatures of Quantum - Tunneling Diffusion of Hydrogen Atoms on Water Ice at 10 K

Quantum tunneling of oxygen atoms on very cold surfaces.

Any evolving system can change state via thermal mechanisms (hopping a barrier) or via quantum tunneling. Most of the time, efficient classical mechanisms dominate at high temperatures. This is why an increase of the temperature can initiate the chemistry. We present here an experimental investigation of O-atom diffusion and reactivity on water ice. We explore the 6-25 K temperature range at su...

Boron Nitride Nanomesh: A template for Nano-ice

Using variable temperature scanning tunneling microscopy and dI/dz barrier height spectroscopy, the structure of water on h-BN/Rh(111) nanomesh has been investigated. Below its desorption temperature, two distinct phases of water self-assemble within the 3.2 nm unit cell of the nanomesh. In the 2 nm holes, an ordered phase of nano-ice crystals with about 40 molecules is found. The ice crystals ...

Tunneling and delocalization effects in hydrogen bonded systems: a study in position and momentum space.

Novel experimental and computational studies have uncovered the proton momentum distribution in hydrogen bonded systems. In this work, we utilize recently developed open path integral Car-Parrinello molecular dynamics methodology in order to study the momentum distribution in phases of high pressure ice. Some of these phases exhibit symmetric hydrogen bonds and quantum tunneling. We find that t...

Overtone spectra and hydrogen potential of H2O at high pressure

The first overtones of the stretching and bending vibrations of H2O and the first stretching overtone of D2O were measured to pressures of 37 GPa at 300 K, encompassing the stability fields of water, ice VI, and ice VII. The successive disappearance of the overtone peaks in ice VII with increasing pressure indicates that the barrier height in the double minimum hydrogen potential decreases at a...