Tag: liquid

Mechanism behind the enormous density increase in highly-compressed liquid water

Mechanism behind the enormous density increase in highly-compressed liquid water

Researchers reveal details behind the microscopic mechanism that enables the large increase of density in compressed water using experimental data from the ESRF and first principles simulations.

Water is one of the most ubiquitous substances and essential for all forms of life on Earth. Its many thermodynamic anomalies render water one of the most extraordinary liquids known to mankind. Yet, after decades of intense research, the structural details at atomic length scales underlying these anomalies remain unclear.

An example of the strange behaviour of water is its density, which is highest at 4 C. This heavily affects water’s buoyancy and impacts ocean circulation and climate patterns. Likewise, water’s low density ice phase, common ice Ih, is less dense than liquid water, a fact that is vital for aquatic life and the stability of our ecosystems. Pressure is one of the fundamental experimental parameters and is often used by researchers to observe a system’s respond to it, yielding invaluable information about the interactions between atoms and molecules at play.

Now an international team of scientists lead by the ESRF have studied pressurized water in its liquid state at atomic length scales. “There is still a lot of controversy as to how hydrogen bonding between water molecules evolves under pressure, so our study aimed to shed light on this question”, explains Christoph Sahle, scientist in charge of beamline ID20 and co-corresponding author of the publication.

Read more on ESRF website

First-ever X-ray attosecond experiment on liquids provides new insights into water’s molecular properties

First-ever X-ray attosecond experiment on liquids provides new insights into water’s molecular properties

Theorists explain how X-ray measurement freezes hydrogen motion, with implications on other areas of chemistry

An international team has performed an attosecond-scale experiment at an X-ray free-electron laser on liquid water for the first time, and the results may change our interpretation of water’s behaviour. The experiment team, led by scientist Linda Young from Argonne National Laboratory in the US, found an unusual signal when they examined liquid water using X-ray flashes that were timed a few hundred attoseconds (an attosecond is a billionth of a billionth of a second). A theory team led by Robin Santra, lead scientist at the research centre DESY and a professor at Universität Hamburg in Germany, and Xiaosong Li, a professor at the University of Washington in the US, used quantum-mechanical techniques for the analysis. Based on the data of the new experiment, they found that a longstanding measurement of the structure of liquid water has been misinterpreted. The effects of this finding not only demonstrate the potential of attosecond research on condensed matter at X-ray lasers, which is so far unprecedented, but also may require a rethink on how a wide range of molecules beyond water, especially organic ones, are structured. The findings have been published in the journal Science.

DESY’s experience and techniques were crucial in this result and form a cornerstone towards the future Centre for Molecular Water Science (CMWS) that DESY is setting up. The experimental and theoretical teams for this result comprise scientists from Argonne National Laboratory, the University of Washington, Pacific Northwest National Laboratory, Washington State University, the University of Chicago, and SLAC National Accelerator Laboratory, all in the US; and DESY, Universität Hamburg, and the Hamburg Cluster of Excellence “CUI: Advanced Imaging of Matter,” all in Germany.

Read more on DESY website

Image: Georgi Dakovski operating the LCLS ChemRIXS beamline, where the experiment was carried out during the pandemic

Credit: Linda Young