Kemi

Rydberg tilstande

25. juni 2007 af apandersen (Slettet)
Er der nogen er kan forklare lidt om hvad rydberg tilstande i molekyler er. Jeg ved godt at det er en form for exiterede tilstande, der skal opfylde rydberg formlen. Men hvad er forskellen mellem dem og de almindelige exiterede tilstande (Hvor en elektron hopper op i en højere skal)? Hvorfor er de der? Hvorfor er de interessante?

Brugbart svar (0)

Svar #1
19. august 2007 af chrisjorg (Slettet)

Wikipedia besvarer alle dine spørgsmål:
The Rydberg states of an atom are electronically excited states with energies that follow the Rydberg formula as they converge on an ionic state with an ionization energy. Although the Rydberg formula was developed to describe atomic energy levels, it has been used to describe many other systems that have electronic structure roughly similar to atomic hydrogen. In general, at sufficiently high principal quantum numbers, an excited electron - ionic core system will have the general character of a hydrogenic system and the energy levels will follow the Rydberg formula. Rydberg states have energies converging on the energy of the ion. The ionization energy threshold is the energy required to completely liberate an electron from the ionic core of an atom or molecule.

Rydberg series describe the energy levels associated with partially removing an electron from the ionic core. Each Rydberg series converges on an ionization energy threshold associated with a particular ionic core configuration. These quantized Rydberg energy levels can be associated with the quasiclassical Bohr atomic picture. The closer you get to the ionization threshold energy, the higher the principal quantum number, and the smaller the energy difference between "near threshold Rydberg states." As the electron is promoted to higher energy levels, the spacial excursion of the electron from the ionic core increases and the system is more like the Bohr quasiclassical picture.

The energy of Rydberg states can be refined by including a correction called the quantum defect in the Rydberg formula. The "quantum defect" correction is associated with the presence of a distributed ionic core. Even for many electronically excited molecular systems, the ionic core interaction with an excited electron can take on the general aspects of the interaction between the proton and the electron in the hydrogen atom. The spectroscopic assignment of these states follows the Rydberg formula and they are called Rydberg states of molecules.


Min fysisk kemi tutor på Merton forsker bla. i Rydberg tilstande:
"My interests as a scientist includes using UV laser spectroscopic techniques in a number of novel experiments in gas-phase chemical physics. These include the properties and applications of highly excited "Rydberg states" of atoms and molecules, the study of photodissociation dynamics, the control of molecular motion using electromagnetic fields and the study of chemical collisions at ultralow temperatures."

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