On the tiniest of scales, chemistry isn't all about 'billiard-ball' reactions

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Scientists are one step closer to understanding how to live in a "quantum" world, not just from watching the character "Ant-Man" in the movie franchise.

Take a look at the protective barrier of the Earth's atmosphere that creates the ozone layer and protects life as we know it. Oxygen is being broken up through a chemical process by the sun's UV rays inside the air layer. Scientists can observe these micro-Interactions on the smallest of scales, the quantum level, while this process is invisible to the naked eye.

In a study recently published in Science, scientists at the University of Missouri provide evidence of the effects of photodissociation on the quantum level for an atmospheric pollutant, formaldehyde, thereby showing photodissociation reactions can't be treated classically.

A chemist is going to miss out on what a molecule is truly doing if they only think of chemical reactions in the classic sense. As a molecule gets very cold, quantum effects are very important. The high energy of photodissociation makes it surprising that strong quantum effects appear. This new insight could change our view of how the molecule behaves, but may also impact the overall chemical makeup, and that in turn could cause the chemistry to go in unexpected ways.

The study deals with roaming, in which photodissociation breaks a molecule into pieces, but the pieces come back and react with each other. "billiard ball" models were able to match such experiments. The study shows that more detailed measurements can't be treated this way.

They have to use a more complicated quantum model to confirm their observations. One day, scientists will be able to better understand the chemistry in the atmosphere, both in the stratosphere where ozone protects us, and at ground level where it is a dangerous pollutant.

"If you want to understand the chemistry of the atmosphere, you first need to understand what happens when light is absorbed and a molecule starts to break down," he said. "Chemists think they don't have to worry about what is happening at the quantum level in photodissociation, but we show here that's not always the case, and they need to be."

"Orbiting resonances in formaldehyde reveal the relationship between roaming, radical, and molecular channels," was published in Science. The co-authors are from the University of New Mexico and the University of Missouri. Northwest University in China has a dual appointment with Xie.

More information is available from Science. There is a science.abk0634

Science journal information.

chemistry isn't all about 'billiard-ball' reactions on the smallest scales.

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