Franck–Condon principle

E4700

physical principle spectroscopic rule

The Franck–Condon principle is a rule in molecular spectroscopy that explains the intensity distribution of vibronic transitions by assuming electronic transitions occur much faster than nuclear motion, making vertical transitions between vibrational states most probable.

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All labels observed (3)

Label	Occurrences
Franck–Condon principle canonical	7
Franck–Condon factors	2
Franck–Condon approximation	1

How this entity was disambiguated

This entity first appeared as the object of triple T65228 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.

NED1 Entity disambiguation (via context triple) gpt-5-mini-2025-08-07

Target entity: Franck–Condon principle
Context triple: [Born–Oppenheimer approximation, usedIn, Franck–Condon principle]

A. Born–Oppenheimer approximation
The Born–Oppenheimer approximation is a fundamental method in molecular quantum mechanics that simplifies calculations by treating nuclear motion as much slower than electronic motion, allowing their behaviors to be separated.
B. Feynman–Hellmann theorem
The Feynman–Hellmann theorem is a result in quantum mechanics that relates the derivative of an energy eigenvalue with respect to a parameter in the Hamiltonian to the expectation value of the corresponding derivative of the Hamiltonian.
C. Einstein coefficients
Einstein coefficients are parameters in quantum theory that quantify the probabilities of absorption, spontaneous emission, and stimulated emission of radiation by atoms or molecules.
D. The Nature of the Chemical Bond
The Nature of the Chemical Bond is a landmark chemistry book by Linus Pauling that systematically explains chemical bonding using quantum mechanics and became one of the most influential scientific texts of the 20th century.
E. Huygens–Fresnel principle
The Huygens–Fresnel principle is a fundamental concept in wave optics that explains how every point on a wavefront acts as a source of secondary wavelets whose interference determines the wave’s subsequent propagation and diffraction.
F. None of above. chosen
G. Unsure - the case is ambiguous/there is not enough information to decide.

NED2 Entity disambiguation (via description) gpt-5-mini-2025-08-07

Target entity: Franck–Condon principle
Target entity description: The Franck–Condon principle is a rule in molecular spectroscopy that explains the intensity distribution of vibronic transitions by assuming electronic transitions occur much faster than nuclear motion, making vertical transitions between vibrational states most probable.

A. Born–Oppenheimer approximation
The Born–Oppenheimer approximation is a fundamental method in molecular quantum mechanics that simplifies calculations by treating nuclear motion as much slower than electronic motion, allowing their behaviors to be separated.
B. Feynman–Hellmann theorem
The Feynman–Hellmann theorem is a result in quantum mechanics that relates the derivative of an energy eigenvalue with respect to a parameter in the Hamiltonian to the expectation value of the corresponding derivative of the Hamiltonian.
C. Einstein coefficients
Einstein coefficients are parameters in quantum theory that quantify the probabilities of absorption, spontaneous emission, and stimulated emission of radiation by atoms or molecules.
D. The Nature of the Chemical Bond
The Nature of the Chemical Bond is a landmark chemistry book by Linus Pauling that systematically explains chemical bonding using quantum mechanics and became one of the most influential scientific texts of the 20th century.
E. Huygens–Fresnel principle
The Huygens–Fresnel principle is a fundamental concept in wave optics that explains how every point on a wavefront acts as a source of secondary wavelets whose interference determines the wave’s subsequent propagation and diffraction.
F. None of above. chosen

Statements (46)

Predicate	Object
instanceOf	physical principle ⓘ spectroscopic rule ⓘ
appliesTo	electronic transitions in molecules ⓘ vibronic transitions ⓘ
assumes	electronic transitions are much faster than nuclear motion ⓘ nuclear coordinates do not change during the electronic transition ⓘ transition dipole moment is weakly dependent on nuclear coordinates ⓘ
basedOn	Born–Oppenheimer approximation ⓘ
concerns	nuclear configuration space ⓘ overlap integrals of initial and final vibrational states ⓘ transition probabilities between vibrational levels ⓘ vertical transitions between potential energy surfaces ⓘ
describes	intensity distribution of vibronic transitions ⓘ
explains	progressions in vibrational structure of spectra ⓘ relative intensities of vibronic lines ⓘ shape of electronic absorption bands ⓘ shape of electronic emission bands ⓘ
field	molecular physics ⓘ molecular spectroscopy ⓘ quantum chemistry ⓘ
implies	most probable transitions are vertical on a potential energy diagram ⓘ nuclei are effectively fixed during an electronic transition ⓘ
mathematicalFormulation	transition intensity proportional to square of vibrational overlap integral ⓘ
namedAfter	Edward Condon ⓘ James Franck ⓘ
predicts	intensity maxima near classical turning points of vibrational motion ⓘ most intense transition originates from the ground vibrational level ⓘ vibrational progressions when equilibrium geometries differ between states ⓘ
relatedTo	Born–Oppenheimer approximation ⓘ Herzberg–Teller approximation ⓘ Huang–Rhys factor ⓘ potential energy curve ⓘ transition dipole moment ⓘ vibronic coupling ⓘ
relates	spectral band intensities to Franck–Condon factors ⓘ transition probability to overlap of vibrational wavefunctions ⓘ
usedFor	analyzing photophysical processes in molecules ⓘ assigning vibrational structure in electronic spectra ⓘ estimating geometry changes upon electronic excitation ⓘ
usedIn	analysis of potential energy surfaces ⓘ computational spectroscopy ⓘ interpretation of molecular absorption spectra ⓘ interpretation of molecular fluorescence spectra ⓘ interpretation of phosphorescence spectra ⓘ photoelectron spectroscopy ⓘ
usesConcept	Franck–Condon factors ⓘ linked to: Franck–Condon principle

How these facts were elicited

Referenced by (10)

Full triples — surface form annotated when it differs from this entity's canonical label.

Born–Oppenheimer approximation → usedIn → Franck–Condon principle ⓘ

Franck–Condon principle → usesConcept → Franck–Condon factors ⓘ

linked to: Franck–Condon principle

Huang–Rhys factor → relatedTo → Franck–Condon principle ⓘ

Huang–Rhys factor → relatedTo → Franck–Condon factors ⓘ

linked to: Franck–Condon principle

Herzberg–Teller approximation → refines → Franck–Condon principle ⓘ

Herzberg–Teller approximation → refines → Franck–Condon approximation ⓘ

linked to: Franck–Condon principle

Edward Condon → knownFor → Franck–Condon principle ⓘ

Edward Condon → coFormulated → Franck–Condon principle ⓘ

Condon approximation → relatedTo → Franck–Condon principle ⓘ

Stokes shift → relatedTo → Franck–Condon principle ⓘ

All labels observed (3)

How this entity was disambiguated Show

Statements (46)

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Referenced by (10)

How this entity was disambiguated

How these facts were elicited