Physics:Quantum atoms/transition: Difference between revisions
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== Historical names == | == Historical names == | ||
* [[Biography:William Hyde Wollaston|William Hyde Wollaston]] observed dark lines in the solar spectrum in 1802, before Fraunhofer mapped them systematically. These observations became part of the experimental history of spectroscopy and quantum atomic transitions. | |||
* [[Biography:Joseph von Fraunhofer|Joseph von Fraunhofer]] mapped dark absorption lines in the solar spectrum. Fraunhofer lines became a key observational background for spectroscopy and the later quantum explanation of atomic transitions. | |||
* [[Biography:Niels Bohr|Niels Bohr]] introduced quantum jumps between atomic energy levels. | * [[Biography:Niels Bohr|Niels Bohr]] introduced quantum jumps between atomic energy levels. | ||
* [[Biography:Albert Einstein|Albert Einstein]] developed transition probabilities for absorption and emission processes. | * [[Biography:Albert Einstein|Albert Einstein]] developed transition probabilities for absorption and emission processes. | ||
* James Franck and Gustav Hertz experimentally confirmed discrete atomic excitation energies. | * [[Biography:James Franck|James Franck]] and [[Biography:Gustav Hertz|Gustav Hertz]] experimentally confirmed discrete atomic excitation energies. | ||
== History == | == History == | ||
Danish physicist [[Biography:Niels Bohr|Niels Bohr]] first proposed quantum jumps in 1913.<ref>{{Cite news|last=Gleick|first=James|date=1986-10-21|title=PHYSICISTS FINALLY GET TO SEE QUANTUM JUMP WITH OWN EYES|language=en-US|work=The New York Times|url=https://www.nytimes.com/1986/10/21/science/physicists-finally-get-to-see-quantum-jump-with-own-eyes.html|access-date=2021-12-06|issn=0362-4331}}</ref> Shortly afterward, the Franck–Hertz experiment by James Franck and Gustav Hertz experimentally confirmed that atoms possess quantized energy states.<ref>{{Cite web|title=Franck-Hertz experiment {{!}} physics {{!}} Britannica|url=https://www.britannica.com/science/Franck-Hertz-experiment|access-date=2021-12-06|website=www.britannica.com|language=en}}</ref> | Danish physicist [[Biography:Niels Bohr|Niels Bohr]] first proposed quantum jumps in 1913.<ref>{{Cite news|last=Gleick|first=James|date=1986-10-21|title=PHYSICISTS FINALLY GET TO SEE QUANTUM JUMP WITH OWN EYES|language=en-US|work=The New York Times|url=https://www.nytimes.com/1986/10/21/science/physicists-finally-get-to-see-quantum-jump-with-own-eyes.html|access-date=2021-12-06|issn=0362-4331}}</ref> Shortly afterward, the Franck–Hertz experiment by [[Biography:James Franck|James Franck]] and [[Biography:Gustav Hertz|Gustav Hertz]] experimentally confirmed that atoms possess quantized energy states.<ref>{{Cite web|title=Franck-Hertz experiment {{!}} physics {{!}} Britannica|url=https://www.britannica.com/science/Franck-Hertz-experiment|access-date=2021-12-06|website=www.britannica.com|language=en}}</ref> | ||
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.<ref name=":0" /> | 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.<ref name=":0" /> | ||
Latest revision as of 09:02, 23 May 2026
transition is a Book II topic in the Quantum Collection. 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. 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. 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. These energy levels are unique to each atom and produce characteristic spectral fingerprints.
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]
Historical names
- William Hyde Wollaston observed dark lines in the solar spectrum in 1802, before Fraunhofer mapped them systematically. These observations became part of the experimental history of spectroscopy and quantum atomic transitions.
- Joseph von Fraunhofer mapped dark absorption lines in the solar spectrum. Fraunhofer lines became a key observational background for spectroscopy and the later quantum explanation of atomic transitions.
- Niels Bohr introduced quantum jumps between atomic energy levels.
- Albert Einstein developed transition probabilities for absorption and emission processes.
- James Franck and Gustav Hertz experimentally confirmed discrete atomic excitation energies.
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