The first molecular structure of water has finally been recorded.

When a solid is submerged in a liquid, the molecular structure of the liquid surrounding the solid's surface differs from the structure of the liquid. Further changes in the interfacial liquid can also happen when the solid's surface is charged.

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Using a new method, researchers from the Lawrence Berkeley National Laboratory (Berkeley Lab) were able to not only observe water molecules next to the electrode surface, but to also determine the changes in their arrangements under different charges.

The researchers used X-Ray Absorption Spectroscopy to study changes in the arrangement of the water molecules in the interfacial layer with a precision never achieved before this study.

X-ray Absorption Spectroscopy is a proven technique to study the arrangement of molecule s but isn't generally effective in water because it dissipates under such conditions.

To safely expose the molecules of water in the X-Ray, researchers designed a thin transparent window with a thin coating of gold. The transparent window allowed X-rays to pass inside the sample.

A thin wire was then attached to the gold electrode to allow the researchers to conduct measurements when electrons were released after exciting the water with X-rays.

Researchers also parted the current by pulsing X-rays at a known frequency to determine which part of the electric current was caused by X-rays or a battery.

These series of experiments produced curves of absorption vs. X-ray energy that show how water molecules within the gold interface absorb the X-rays.

Finally, researchers conducted large molecular dynamics simulations of the interface of water and gold to translate the information shown by the curves into a molecular structure.

"Water next to the electrode has a different molecular structure than it would in the absence of the electrode," concluded Miquel Salmeron, a senior scientist at Berkeley Lab.

The structure of water molecules at the interfacial layer is important to understand different phenomena in fields such as biology and material science. The study was published online in the journal, Science. 

TagsBerkeley Lab, Molecular Structure of Water, Gold Electrodes, Godl Surface, Interfacial Layer