What is the state of an atom

Suggestion

Suggestion, 1) Atomic physics: Process in which atoms, molecules or ions from one Own state certain energy can be transferred into a state of higher energy. The initial state can be the Basic state or an excited state, in which case a first excitation process must have preceded it. In the image of Bohr's atomic model (atomic models) this process is explained by the fact that an electron is lifted from an orbit close to the nucleus to an orbit with a greater distance between the nuclei. The energy absorption of the atom can take place in different ways. The most important are the absorption of electromagnetic radiation and shock excitation. The collision partners can be electrons or heavy ions. In the case of thermal excitation, the energy is transferred through collisions with other neutral atoms in the gas. In the case of thermal excitation, the Boltzmann distribution applies to the occupation of the individual levels.

Is n0 the number density of atoms in a certain state of energy E.0, then is the number density na of atoms in an excited state of energy E.a given by:



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Are there Ga and G0 the statistical weights of the respective states, i.e. the numbers of degenerate sub-states, kB. is the Boltzmann constant and T the absolute temperature.

The selective excitation of certain atomic energy levels is particularly well possible with the aids of modern laser spectroscopy (laser excitation). The simplest way of suggesting is One step excitation, where the energy difference between the levels involved corresponds to the energy of a photon. In the Multi-stage excitation If several photons are absorbed by the atom or molecule, the energies of which can differ from one another, whereby the individual photons excite intermediate states. If the atom or molecule absorbs several photons of the same energy, one speaks of Multi-photon excitation. The excitation does not have to go through a resonant intermediate state. An overview of these three processes is shown in the figure.