The Name's Bond… Hydrogen Bond

Hydrogen bonds underlie the unique traits of a molecule used by the atmosphere to break down pollutants, especially the compounds that cause acid rain.

The molecule, which had not been seen before, is unusual because it has two hydrogen bonds. This image above shows the structure of the molecule, with a blue nitrogen atom, red hydrogen atoms, white oxygen atoms, and yellow clouds showing the location of the double hydrogen bonds.

Chemists Marsha Lester from the University of Pennsylvania and Joseph Francisco from Purdue University found the molecule, which had puzzled and eluded scientists for more than 40 years.

A technical paper describing the molecule is published last week in a special edition of the Proceedings of the National Academy of Science.

Similar to a human body metabolizing food, the Earth's atmosphere can "burn," or oxidize pollutants, especially nitric oxides emitted from sources such as factories and automobiles. What doesn't get oxidized in the atmosphere falls back to Earth in the form of acid rain.

"The chemical details of how the atmosphere removes nitric acid have not been clear," Francisco says. "This gives us important insights into this process. Without that knowledge we really can't understand the conditions under which nitric acid is removed from the atmosphere."

He says the discovery will allow scientists to better model how pollutants react in the atmosphere and to predict potential outcomes.

This is especially important in emerging industrial nations such as China, India and Brazil where automobiles and factories are unregulated, said Francisco. "This chemistry will give us insight into the extent that acid rain will be a future concern."

-- LiveScience Staff

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Image Credit: Joseph Francisco, Purdue News Service