200 years later, key physical chemistry puzzle may be solved

(ORDO NEWS) — The question of exactly how protons move through water in an electric field has puzzled scientists for centuries. Now, more than 200 years after the last serious study of this phenomenon, scientists have some clarity.

In 1806, Theodor Grotthuss hypothesized what became known as the Grotthuss mechanism for “proton hopping”. ‘, about how charge can flow through a solution of water.

While the Grotthuss hypothesis was very far-sighted for its time it appeared before protons or even the actual structure of water was known modern researchers have long known that it does not provide a full understanding of what happened at the molecular level.

Recent discoveries on this topic may have solved the mystery by resolving the electronic structures of hydrated protons that have remained elusive for so long.

The findings show that the protons move through the water in “trains” of three water molecules, with the “caterpillars” being built in front of the train as it moves and rising once. it’s passed.

This loop can continue indefinitely to transport protons t through the water. While this idea has been proposed before, the new study identifies a different molecular structure that the study authors say better fits the solution proposed by Grotthuss.

“Controversy about the Grottuss mechanism and the nature of proton solvation in water has heated up as it is one of the most basic problems in chemistry,” says chemist Ehud Pines of Ben-Gurion University of the Negev in Israel.

The new study is compelling because it combines a theoretical approach with physics experiments made possible by recent technological advances . The researchers used an X-ray absorption spectroscopy (XAS) experiment to trace how proton charges affect electrons in individual oxygen atoms in water.

As predicted, three water molecules were most affected, albeit at different extents of each individual molecule within the trimeric cluster . The researchers found groups of three molecules forming chains with a proton.

The researchers also included chemical modeling and quantum-level calculations to determine the interactions between protons and neighboring water molecules as the protons move through the liquid.

“Understanding this mechanism is pure science, expanding the boundaries of our knowledge and changing one of our fundamental ideas about one of the most important mass and charge transfer mechanisms in nature,” says Pines.

The discovery plays a role in many other chemical processes, including photosynthesis, cellular respiration and energy transport in hydrogen fuel cells.

Not only is the solution remarkable, but how the researchers were able to arrive at it—testing and testing theoretical predictions against experimental results, and vice versa, in a long tortuous process that took almost two decades from start to finish.

“Everyone has been thinking about this issue for over 200 years, so it was enough of a challenge for me to make a decision,” says Pines. “Seventeen years later, I’m glad I found and demonstrated the solution.”


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