Lively state – Wikipedia
A lively state A physical system is every condition whose energy is greater than the lowest possible, i.e. H. larger than the energy of the basic state. The term is mainly used for systems that can only assume conditions with certain discrete energies, as described by quantum mechanics.
Experience has shown that a self -leaving physical system usually strives to provide the lowest energy content by handing over energy. This can be explained by the probabilities of the different system states in the phase space: an energy that has once been submitted in any form (through friction, nuclear fission, generation and emission of new particles such as photons, β-radiation, etc.) generally only returns to the starting system with a negligible probability return. A lively state is therefore generally not stable, but has a finite average lifespan In other words, a dismantling probability per time span for the transition to a less highly excited state or the basic state. The middle lifespan can be from a fraction of a second to thousands of years. Measured values cover up an area of 55 ten potencies, probably the largest that occurs with a physical measurement variable.
Sometimes lively conditions with a particularly long lifespan are sometimes as metastabil designated; see z. B. isomer (nuclear physics).
The basic state of an atom is determined by the energetically lowest electron configuration. Through energy supply, e.g. B. by absorbing a photon with suitable energy (light) or by an unelastic impact ( Shock suggestion , see z. B. Franck-Hertz attempt), an electron can be raised to a higher energy level ( Doctoralization , Stimulation ). The decay into an energetically lower state ( Abregung ) either spontaneously or is triggered by an external disorder. The free energy is released to the environment in any form, e.g. B.:
If the basic state does not settle in the usual, very short time of less than a microsecond, one speaks of one metastable condition , [first] Which can be explained by conflicting selection rules. The disintegration of a metastable state is also referred to as a forbidden transition.
With hydrogen atom, the spins from electron and proton can be parallel or anti -parallel. The anti -parallel state has slightly lower energy, which is radiated as a photon when folded back. This radiation is an important method of detection of astronomy for heavily diluted hydrogen gas.
The flame coloring by alkaline and earth-alkalimetals is explained by shock suggestion. There, the energy intake is generated by bumps between the atoms (and molecules) in the hot flame – i.e. through heat.
Light is also in the game in the game generated in gas discharge tubes (e.g. neon tubes). The flowing electrical current causes bumps between free electrons and the atoms, which lead to suggestion or ionization. In the case of northern lights, protons of cosmic radiation and free electrons trigger from them cause the bumps. A recombination takes place after ionization. This usually runs through lively conditions. In their decay, the free energy is emitted as light.
Ionizing radiation can make atoms out of their lattice places. If these no longer return to their original position, crystal errors arise that may last long. This represents a form of energy storage. Thermoluminescence can be used to convert these metastable stable stables into light. If neutrons cause these lattice errors in graphite, one speaks of Wigner energy.
In order to characterize the line -up of lively conditions in multi -particle systems, a description of quasi -particles is often used. For example, the stimulation of lattice vibrations in a crystal can be described as the production of phonons.
- Jörn Bleck-Neuhaus: Elementary particles. Modern physics from atoms to the standard model (Chapter 6) . Springer, Heidelberg 2010, ISBN 978-3-540-85299-5.
- ↑ Bergmann-Schaefer: Textbook of experimental physics , Volume 4: Partchen, de Gruyter, Berlin, 1992, ISBN 3-11-010977-8, p. 241.
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