A molecule of ammonia, NH3, typically exists as an umbrella shape, with three hydrogen atoms fanned out in a nonplanar arrangement around a central nitrogen atom.
A molecule of ammonia, NH3, typically exists as an umbrella shape, with three hydrogen atoms fanned out in a nonplanar arrangement around a central nitrogen atom. This umbrella structure is very stable and would normally be expected to require a large amount of energy to be inverted.
However, a quantum mechanical phenomenon called tunneling allows ammonia and other molecules to simultaneously inhabit geometric structures that are separated by a prohibitively high energy barrier. A team of chemists that includes Robert Field, the Robert T. Haslam and Bradley Dewey Professor of Chemistry at MIT, has examined this phenomenon by using a very large electric field to suppress the simultaneous occupation of ammonia molecules in the normal and inverted states.
“It’s a beautiful example of the tunneling phenomenon, and it reveals a wonderful strangeness of quantum mechanics,” says Field, who is one of the senior authors of the study.
Heon Kang, a professor of chemistry at Seoul National University, is also a senior author of the study, which appears this week in the Proceedings of the National Academy of Sciences. Youngwook Park and Hani Kang of Seoul National University are also authors of the paper.
Read more at Massachusetts Institute of Technology
Image: MIT chemists have observed, for the first time, inversion of the umbrella-like ammonia molecule by quantum tunneling. CREDIT: Chelsea Turner, MIT
