Electronic Transition

The electronic transitions are the passage of a electron of a Energy level to another.

The electron of the Energy level $E_0$ , excited by a electromagnetic Rayonnement passes to the Energy level higher E1. In the simplest case of a Atom of Hydrogen (a electron and a Proton), the electron is trapped in the Electric field created by the proton. The quantum Mechanical , contrary to the traditional Mechanical , provides that the electron can then exist only in certain quantum states, of well determined energy, one speaks about quantification of energy. That it is under the effect of the light, the collisions, an electric shock in a gas, etc, one can thus attend only discrete energy exchanges between the atom and its environment.

This was particularly visible in the spectra of the gas-discharge lamps of the end of the 19th century. The Physicien S of this time gathered the transitions which they saw in various series (known as of Lyman, Balmer, Paschen, Brackett, Pfund according to the physicist which had identified them), first of all without including/understanding why these transitions answered the formula

E_ {transition} =R_ {H} (1/m^ {2} - 1/n^ {2})

These spectra largely contributed to sit the quantum Mécanique when one realized that one observed there the electronic transition between levels N and m from the atom.

quantum systems more complex than the atoms, such as the Molecule S or the Solide S also present electronic transitions . However, it happens that the electronic states couple with others states, for example of the states of vibration of the molecule or Crystal lattice, and one cannot then speak about electronic transition purely any more.

See too

Spectrometry
Notation of Siegbahn

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