UNIST study uncovers proton tunneling in water molecules

A research team from UNIST has studied a unique behavior of water molecules. They focused on a special arrangement of three water molecules shaped like a triangle. Their findings are published in the journal Nano Letters. The researchers found that the motion of these water molecules helps protons move in a way that they can bypass energy barriers. This is a quantum effect known as proton tunneling. This discovery may change the way we understand chemical reactions and the stability of vital biological molecules like DNA. When the team activated the rotational motion of the water molecules, they noticed the distances between the molecules changed. This phenomenon enhances the way protons work together and helps them overcome energy barriers. To do this, the researchers used advanced techniques like Scanning Tunneling Microscopy to study the triangular structure of the water molecules. The team placed the water molecules on a salt film in extremely cold conditions to prevent evaporation. They discovered that the triangular shape of the water molecules would distort and shift frequently. This movement is evidence that proton tunneling can happen even at very low temperatures. When a specific voltage was applied to the triangular structure, it began to resemble a perfect triangle. This indicated that the voltage activated the movement of the molecules, adjusting the hydrogen bonding distances. The research also included comparisons of the tunneling rates of ordinary water and deuterium oxide. The researchers noted that water's strong hydrogen bonds made this study difficult. By isolating just three water molecules, they were able to overcome this challenge. Professor Hyung-Joon Shin highlighted that their findings show how molecular motion and cooperation among water molecules are key to regulating proton tunneling. This could lead to new methods for controlling chemical reactions and energy processes.