Tuesday, January 24, 2012

Rice lab mimics Jupiter's Trojan asteroids inside a single atom - YouTube



Rice University physicists have built an accurate model of part of the solar system inside a single atom.

In a new paper in Physical Review Letters, Rice's team and collaborators from Oak Ridge National Laboratory and the Vienna University of Technology showed they could make an electron orbit the atomic nucleus in the same way that Jupiter's Trojan asteroids orbit the sun.

The findings uphold a 1920 prediction by physicist Niels Bohr.

"Bohr predicted that quantum mechanical descriptions of the physical world would, for systems of sufficient size, match the classical descriptions provided by Newtonian mechanics," said lead researcher Barry Dunning, Rice's Sam and Helen Worden Professor of Physics and chair of the Department of Physics and Astronomy.

"Bohr also described the conditions under which this correspondence could be observed. In particular, he said it should be seen in atoms with very high principal quantum numbers, which are exactly what we study in our laboratory."

Bohr was a pioneer of . His 1913 atomic model, which is still widely invoked today, postulated a small nucleus surrounded by electrons moving in well-defined orbits and shells.

The word "quantum" in quantum mechanics derives from the fact that these orbits can have only certain well-defined energies.

Jumps between these orbits lead to absorption or emission of specific amounts of energy termed quanta.

As an electron gains energy, its quantum number increases, and it jumps to higher orbits that circle ever farther from the nucleus.

In the new experiments, Rice graduate students Brendan Wyker and Shuzhen Ye began by using an to create a Rydberg atom.

Rydberg atoms contain a highly excited electron with a very large quantum number. In the Rice experiments, potassium atoms with quantum numbers between 300 and 600 were studied.

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