Physics:Quantum atoms/transition: Difference between revisions
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A '''transition''' is a change of an [[Physics:Quantum atoms/electron|electron]] between different [[Physics:Quantum atoms/energy level|energy levels]] in an [[Physics:Quantum atoms/atom|atom]]. Such transitions occur when energy is absorbed or emitted, typically in the form of a photon. | A '''transition''' is a change of an [[Physics:Quantum atoms/electron|electron]] between different [[Physics:Quantum atoms/energy level|energy levels]] in an [[Physics:Quantum atoms/atom|atom]]. Such transitions occur when energy is absorbed or emitted, typically in the form of a photon. | ||
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[[File:Atomic_transition_yellow_landscape-1.png|thumb|280px|Quantum atoms/transition.]] | |||
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== Description == | == Description == | ||
In [[Physics:Quantum mechanics|quantum mechanics]], electrons in atoms occupy discrete quantized energy levels. An '''atomic electron transition''' (also called a ''quantum jump'' or ''quantum leap'') occurs when an electron changes from one energy level to another within an atom or artificial atom.<ref>Schombert, James. [http://abyss.uoregon.edu/~js/cosmo/lectures/lec08.html "Quantum physics"] University of Oregon Department of Physics</ref><ref>{{Cite journal |arxiv = 1009.2969|bibcode = 2011PhRvL.106k0502V|title = Observation of Quantum Jumps in a Superconducting Artificial Atom|journal = Physical Review Letters|volume = 106|issue = 11|article-number = 110502|last1 = Vijay|first1 = R|last2 = Slichter|first2 = D. H|last3 = Siddiqi|first3 = I|year = 2011|doi = 10.1103/PhysRevLett.106.110502|pmid = 21469850| s2cid=35070320 }}</ref> | In [[Physics:Quantum mechanics|quantum mechanics]], electrons in atoms occupy discrete quantized energy levels. An '''atomic electron transition''' (also called a ''quantum jump'' or ''quantum leap'') occurs when an electron changes from one energy level to another within an atom or artificial atom.<ref>Schombert, James. [http://abyss.uoregon.edu/~js/cosmo/lectures/lec08.html "Quantum physics"] University of Oregon Department of Physics</ref><ref>{{Cite journal |arxiv = 1009.2969|bibcode = 2011PhRvL.106k0502V|title = Observation of Quantum Jumps in a Superconducting Artificial Atom|journal = Physical Review Letters|volume = 106|issue = 11|article-number = 110502|last1 = Vijay|first1 = R|last2 = Slichter|first2 = D. H|last3 = Siddiqi|first3 = I|year = 2011|doi = 10.1103/PhysRevLett.106.110502|pmid = 21469850| s2cid=35070320 }}</ref> | ||
Revision as of 14:24, 17 May 2026
A transition is a change of an electron between different energy levels in an atom. Such transitions occur when energy is absorbed or emitted, typically in the form of a photon.
Description
In quantum mechanics, electrons in atoms occupy discrete quantized energy levels. An atomic electron transition (also called a quantum jump or quantum leap) occurs when an electron changes from one energy level to another within an atom or artificial atom.[1][2]
These energy levels are unique to each atom and produce characteristic spectral fingerprints. Techniques such as energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy rely on these characteristic transitions to identify atomic composition.[3]
When an electron moves to a higher energy level, it absorbs energy. When it falls to a lower level, it emits energy. These processes are governed by quantum-mechanical selection rules and conservation of energy.
Transitions between energy levels produce discrete spectral features and are fundamental to atomic spectroscopy.
Photon absorption and emission
Electrons can relax into lower-energy states by emitting electromagnetic radiation in the form of photons. Conversely, they can absorb photons and become excited into higher-energy states.
The energy of the photon must exactly match the energy difference between the two states. Larger energy gaps correspond to shorter photon wavelengths.[4]
The relation between photon energy and frequency is:
- contentReference[oaicite:0]{index=0}
where h is the Planck constant, ν is frequency, c is the speed of light, and λ is wavelength.
Quantum theory
An atom interacting with electromagnetic radiation experiences an oscillating electric field:
- contentReference[oaicite:1]{index=1}
where ω is the angular frequency and ĕrad is the polarization vector.[5]
The interaction Hamiltonian for an atomic dipole in an electric field is:
- contentReference[oaicite:2]{index=2}
Using time-dependent perturbation theory and Fermi’s golden rule, the stimulated transition probability depends on the dipole matrix element:
- contentReference[oaicite:3]{index=3}
The angular part of this expression leads directly to the quantum-mechanical selection rules for atomic transitions.
Electromagnetic radiation interactions
To excite an electron into a higher energy level, incident radiation must have energy equal to the energy gap between the levels. Because atomic energy differences are often on the scale of ultraviolet and X-ray photons, these wavelengths are widely used in spectroscopy.[3]
The Franck–Condon principle states that electronic transitions occur much faster than nuclear motion. As a result, transitions occur essentially instantaneously compared to atomic vibrations and are only likely if the initial and final wavefunctions overlap significantly.[6]
Radiative relaxation produces photons with wavelengths characteristic of the atom and transition involved.
Spectroscopy techniques
Several experimental methods use electron transitions:
- Ultraviolet–visible spectroscopy uses visible or ultraviolet light to probe absorption and transmission spectra.[7]
- Energy-dispersive X-ray spectroscopy excites inner-shell electrons using high-energy electrons and measures emitted X-rays characteristic of the atom.[8]
- X-ray photoelectron spectroscopy uses incident X-rays to eject electrons from surfaces and determine elemental composition from their binding energies.[9]
History
Danish physicist Niels Bohr first proposed quantum jumps in 1913.[10] Shortly afterward, the Franck–Hertz experiment by James Franck and Gustav Hertz experimentally confirmed that atoms possess quantized energy states.[11]
In 1975, Hans Dehmelt predicted that individual quantum jumps could be observed directly. In 1986, quantum jumps were experimentally observed using trapped ions of barium and mercury.[4]
Recent discoveries
In 2019, experiments with superconducting artificial atoms demonstrated that some quantum jumps evolve continuously and can even be reversed during the transition.[12]
Other quantum jumps remain fundamentally unpredictable due to the probabilistic nature of quantum measurement.[13]
Properties
- involves energy levels
- associated with emission or absorption of photons
- produces spectral lines
- governed by quantum selection rules
- fundamental to spectroscopy and laser physics
See also
Table of contents (84 articles)
Index
Full contents
References
- ↑ Schombert, James. "Quantum physics" University of Oregon Department of Physics
- ↑ Vijay, R; Slichter, D. H; Siddiqi, I (2011). "Observation of Quantum Jumps in a Superconducting Artificial Atom". Physical Review Letters 106 (11). doi:10.1103/PhysRevLett.106.110502. PMID 21469850. Bibcode: 2011PhRvL.106k0502V.
- ↑ 3.0 3.1 McQuarrie, Donald A.; Simon, John D. (200). Physical chemistry: a molecular approach. Sausalito, Calif: Univ. Science Books. ISBN 978-0-935702-99-6.
- ↑ 4.0 4.1 Itano, W. M.; Bergquist, J. C.; Wineland, D. J. (2015). "Early observations of macroscopic quantum jumps in single atoms". International Journal of Mass Spectrometry 377: 403. doi:10.1016/j.ijms.2014.07.005. Bibcode: 2015IJMSp.377..403I. http://tf.boulder.nist.gov/general/pdf/2723.pdf.
- ↑ Foot, CJ (2004). Atomic Physics. Oxford University Press. ISBN 978-0-19-850696-6.
- ↑ de la Peña, L.; Cetto, A. M.; Valdés-Hernández, A. (2020-12-04). "How fast is a quantum jump?". Physics Letters A 384 (34). doi:10.1016/j.physleta.2020.126880. ISSN 0375-9601. Bibcode: 2020PhLA..38426880D. https://www.sciencedirect.com/science/article/pii/S0375960120307477.
- ↑ "UV-Visible Spectroscopy". https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/spectrpy/uv-vis/uvspec.htm.
- ↑ "Identification and analytical methods" (in en-US), Heterogeneous Micro and Nanoscale Composites for the Catalysis of Organic Reactions (Elsevier): pp. 33–51, 2022-01-01, https://www.sciencedirect.com:5037/science/chapter/edited-volume/abs/pii/B9780128245279000010, retrieved 2025-12-09
- ↑ "X-ray Photoelectron Spectroscopy" (in en). https://serc.carleton.edu/msu_nanotech/methods/xps.html.
- ↑ Gleick, James (1986-10-21). "PHYSICISTS FINALLY GET TO SEE QUANTUM JUMP WITH OWN EYES" (in en-US). The New York Times. ISSN 0362-4331. https://www.nytimes.com/1986/10/21/science/physicists-finally-get-to-see-quantum-jump-with-own-eyes.html.
- ↑ "Franck-Hertz experiment | physics | Britannica" (in en). https://www.britannica.com/science/Franck-Hertz-experiment.
- ↑ Minev, Z. K.; Mundhada, S. O.; Shankar, S.; Reinhold, P.; Gutiérrez-Jáuregui, R.; Schoelkopf, R. J..; Mirrahimi, M.; Carmichael, H. J. et al. (3 June 2019). "To catch and reverse a quantum jump mid-flight". Nature 570 (7760): 200–204. doi:10.1038/s41586-019-1287-z. PMID 31160725. Bibcode: 2019Natur.570..200M.
- ↑ Snizhko, Kyrylo; Kumar, Parveen; Romito, Alessandro (2020-09-29). "Quantum Zeno effect appears in stages". Physical Review Research 2 (3). doi:10.1103/PhysRevResearch.2.033512. Bibcode: 2020PhRvR...2c3512S. https://link.aps.org/doi/10.1103/PhysRevResearch.2.033512.
Source attribution: Physics:Quantum atoms/transition