How big is the smallest droplet? It’s made up of five water molecules.

It has long been thought that the smallest droplets are clusters of water molecules made up of six water molecules. But the latest results from Jiang Ling, a researcher at the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences, and a team of Yang Xueming academicians, as well as a team of professors at Tsinghua University, have broken through this perception by proving that the smallest droplets are made up of five clusters of water molecules. The results were published in the Proceedings of the National Academy of Sciences.

How big is the smallest droplet? It's made up of five water molecules.

Water in nature does not exist in the form of a single water molecule (H2O), but is formed by a number of water molecules formed by the action of hydrogen bonds to form a cluster of water molecules, commonly known as water clusters. In the study, the team found that there is a three-dimensional structure in a cluster of five water molecules, which proves that the smallest droplets are made up of five water clusters.

Jiang Ling introduced that they used Dalian coherent light source, revealed that the water molecule pentapolymer under limited temperature conditions has begun to present the structural characteristics and spectral characteristics of the body water, thus opening up the microstructure evolution of water provides a new way of thinking, from a new perspective to explain the mystery of water, breaking through the long-term people’s traditional understanding that the minimum water droplet is composed of six water molecular clusters.

In the study, Jiang Ling and Yang Xueming team used the independently developed infrared spectroscopic experimental device based on the neutral cluster of Dalian coherent light source, and for the first time found that five water molecular cluster (H2O) 5 showed significant OH telescopic vibration in the 3500-3600cm-1 interval, with the characteristic peak of three-dimensional water cluster structure. Using the self-compiled TGMin program combined with high-precision quantum chemistry theory methods, Li’s team calculated the various stable structures and infrared spectra of water clusters, which were highly consistent with the experiment. The research shows that under the limited temperature condition, the two-dimensional and three-dimensional structure of (H2O) 5 can coexist, and the formation of three-dimensional structure is the root cause of the significant change of infrared spectrum, so that the “three-center di-hydrogen bond” model is proposed, and the formation mechanism of the network structure of the water cluster cluster is analyzed accurately.

According to the introduction, the research has been supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences strategic pilot special, the Chinese Academy of Sciences International Science Program to cultivate special funds such as special funds