Chemists discovered that a reaction between two common molecules occurs much faster at cold interstellar temperatures than on our toasty Earth. Their experiments show that methanol, commonly known as wood alcohol, and hydroxyl react rapidly at –210 degrees Celsius to form methoxy, which has also been spotted in space.
That’s a bit surprising, because it ordinarily takes some energy to get the reaction going. And there’s much more ambient energy in warm environments than in frigid space.
Quantum tunneling may explain the otherwise unlikely reaction. In quantum mechanics, a tiny object can zip right through an energy barrier that it would otherwise have to surmount in order for a chemical reaction to take place. Imagine some drops of water zipping straight through a dam rather than going over the top.
How do interstellar temperatures speed the reaction? An intermediate molecule that exists briefly during the reaction is much more stable in the cold. The stability gives the reaction more time to proceed via the quantum tunneling option.
[Robin J. Shannon et al., Accelerated chemistry in the reaction between the hydroxyl radical and methanol at interstellar temperatures facilitated by tunneling, in Nature Chemistry]
So if you’re mixing up an interstellar brew, bring your quantum cookbook.
—John Matson
[Scientific American is part of the Nature Publishing Group.]
