Quantum tunneling allows "impossible" molecules to form in spaceS

The extreme cold of space should make chemical reactions next to impossible, particularly those involving the formation of complex molecules. And yet the rate of one such chemical reaction is 50 times greater in the cold of space that it is in room temperature. What gives?

The answer, according to researchers at the UK's University of Leeds, is found in quantum mechanics. The researchers sought to explain the detection last year of a highly reactive molecule known as a methoxy radical. The existence of these complex molecules could not be explained using the standard model, which assumes interstellar dust clouds play a key role in initiating these reactions. These particular molecules, however, seemed to have formed from methanol gas in more or less empty space, where temperatures should be too cold for any such chemical reactions to occur. Somehow, the molecules are finding the energy to undergo these reactions when no such energy should be available.

The solution, according to Professor Dwayne Heard, who led the research, is quantum tunneling:

"The answer lies in quantum mechanics. Chemical reactions get slower as temperatures decrease, as there is less energy to get over the 'reaction barrier'. But quantum mechanics tells us that it is possible to cheat and dig through this barrier instead of going over it. This is called 'quantum tunneling'. We suggest that an 'intermediary product' forms in the first stage of the reaction, which can only survive long enough for quantum tunneling to occur at extremely cold temperatures. If our results continue to show a similar increase in the reaction rate at very cold temperatures, then scientists have been severely underestimating the rates of formation and destruction of complex molecules, such as alcohols, in space."

For more on this story, check out the University of Leeds website.

Image of interstellar space via NASA. Image credit: NASA/JPL-Caltech/ESA/CXC/STScI.