Water is a plentiful and vital substance that may be found all around the planet. Despite its familiarity and straightforward form, water has a surprising number of physical properties. Scientists have been studying the structure of water for more than a century, aiming to better understand it.
A group of international academics lead by a Hiroshima University professor has devised a method for reproducing the double peak feature of x-ray emission spectroscopy (XES) spectra in liquid water.
Physical Review Letters released a study conducted by Osamu Takahashi, an associate professor at Hiroshima University’s Graduate School of Advanced Science and Engineering, that advances our understanding of the structure of water on February 25.
As scientists have attempted to better understand the structure of liquid water over the years, some have used a two-structure model to do so. A uniform, continuous liquid model has been adopted by other scientists in a variety of domains. For researchers examining compounds with heterogeneous properties, XES has proven to be a beneficial tool.
Scientists have been debating how to interpret XES spectra of liquid water for almost a decade. The research team used molecular dynamics computations to develop model structures of liquid water in order to overcome this difficulty. The team then used first-principles quantum mechanical simulations to estimate XES spectra for liquid water.
Development of new materials such as electrodes used in batteries, biomaterials such as artificial blood vessels, and functional polymers such as water treatment membranes may be fascinating projects, which are related to the structure of liquid water.
Osamu Takahashi
The team was able to replicate the double 1b1 characteristic found in liquid water’s x-ray emission spectroscopy theoretically. To determine the shape of the XES spectra, they investigated several effects such as geometry and kinetics.
The team was able to create the structure of water in the liquid phase using conventional molecular dynamics simulations. The researchers ran these simulations at different temperatures while keeping the link length and water molecule orientations constant.
The researchers were able to duplicate features in the spectra they estimated, such as the double peaks of the 1b1 state, that had previously been identified in real XES spectra by other scientists.
The researchers grouped the XES spectra they produced based on the different sorts of hydrogen bonding to better comprehend the patterns they were seeing. In all of the many types of hydrogen bonding they looked at, they noticed the double peak signature in the XES spectra.
The researchers looked at the effect of thermally activated vibrational modes on the XES spectra after looking at the spectra associated to hydrogen bonding. They were able to get nine different vibrational modes and investigate their influence on the spectra.
By analyzing the effects of complete vibrational modes, O-H stretching, bending, and rotational modes, the researchers were able to successfully duplicate the XES spectra of liquid water. By looking at the hydrogen-bond arrangement around the excited water molecule and core-hole induced dynamics, they were able to explain both the temperature and isotope dependence.
“Our procedure is general and can be applicable for various systems related to the phenomena including liquid water,” Takahashi said.
The researchers expect that their findings will assist to address some of the long-standing questions about the structure of liquid water. In the future, the researchers believe their approach might be used in a variety of ways.
“Development of new materials such as electrodes used in batteries, biomaterials such as artificial blood vessels, and functional polymers such as water treatment membranes may be fascinating projects, which are related to the structure of liquid water,” Takahashi said.
The research team led by Osamu Takahashi, included Ryosuke Yamamura from the Department of Chemistry, Hiroshima University, Japan; Takashi Tokushima from MAX IV Laboratory, Lund University, Sweden; and Yoshihisa Harada from the Institute for Solid State Physics and Synchrotron Radiation Research Organization, University of Tokyo, Japan. The Japanese Society for the Promotion of Science funded this research.
