Atomic physics: correspondence principle of quantum mechanics demonstrated on highly excited lithium atoms
Rutherford’s vivid planetary model of the atom says very rough railroads in the border case the frequency of the radiated light, which corresponds to the circulation frequency of the electron, ultimately correct; More specifically, it corresponds to the diminishes of adjacent energy levels according to a boring nuclear model. As American experiments find out, a valence electron with a microwave pulse of a frequency corresponding to the circulation frequency drove, and forcing with a variation of the radiation frequency even at higher or lower orbital. A potential application would be a datastore that significantly more than one bit per atom – but probably only in the city’s decade.
Since the development of quantum mechanics in the mid-20s, the Rutherford’s nuclear model is only of historical interest. As the quantum mechanism shows, the illustrative idea of this planetary model for a hydrogen atom in the ground state leads to a qualitatively incorrect prediction: the electron swirls – contrary to the planet model – not around the nucleus, its railway pulse disappears rather, even the electron swings through the core even through the core.
However, for coarse railroad radii and thus for rough major quantum numbers N, however, the matter is very clear: If the electron falls into the next lower orbital, it radiates light, the frequency of which is equal to that of the railway circulation according to the Rutherfordschem planetary model. In short, the electron behaves like an antenna.
Reconciliation leads to the wooden trough
This situation is called correspondence principle: Quantum mechanics must reproduce very coarse railroads in the borderline case the classic mechanics. Atoms with an electron in an orbital very gross main quantum number over 10, so very coarse train radius, prevailing Rydberg atoms, the electron is very high in this case, so almost to the ionization limit.
Researchers of the University of Virginia in American Charlottesville went a step further: they grabbed with a terrified microwave pulse of a duration of 500 nanoseconds on valence electrons of lithium atoms and moved it to a low or a high orbital.
Non-monochromatic, but tarded microwave radiation stimulates the umbreptange between the energy levels of the electrons, illustrating the drawn shaft. The external electron moves synchronously to the applied electric field E, which in the image indicated orbitalgrobe and thus the binding energy is correspondingly. With decreasing radiation frequency, the railway radius decreases, it varies between 13 and 19 GHz.
Normally, spectroscopic electronubergange on the other hand with monochromatic light. The frequency of the microwave pulse varied between 13 and 19 GHz. By means of a dye laser, they previously stulmented the valence electron of the alkali atom to an orbital near the ionization threshold.
The circulation frequency is required according to the microwave frequency varied between the beginning and end of the pulse. The frequencies 13 and 19 Gigahertz correspond to orbital with the main quantum numbers n = 79 or 70, in the basic state of the lithium valence electron is equal to 2. Detection can be detected by the excited electrons using field ionization, an effect that originates from tunneling. The lower the binding energy, the smaller the at least required electric field strength. The American researchers reported their results in the online edition of the magazine Science on 10. February 2005.
Data processing as a conceivable, fine application
As a potential application of the Rydberg atoms, the authors call the data processing. According to Brockhaus-Lexicon, 2002 ie, theoretically many bits love to store at least one byte, with a single atom of high order number, the information then carried several highly excited electrons, whereby the data could be encoded as electronic energy levels. That’s science fiction.