Electric-dipole transition selection rules
In the long-wavelength electric-dipole approximation, atomic transition strength depends on the dipole matrix element.
Key knowledge
In the long-wavelength electric-dipole approximation, atomic transition strength depends on the dipole matrix element. For hydrogenic orbital states without spin-dependent coupling, nonzero matrix elements require Δl=±1, Δm_l=0,±1 and unchanged spin projection; these conditions alone do not guarantee a nonzero rate.
Values and equations
d_fi=⟨f|q r|i⟩; Δl=±1; Δm_l=0,±1; Δm_s=0
- d_fi
- Electric-dipole matrix element C m
- q
- Particle charge C
- r
- Position operator m
- l,m_l,m_s
- Dimensionless orbital/spin labels
- |i⟩,|f⟩
- Normalized states
Conditions and scope
- Atom size small compared with the radiation wavelength and the specified central-field orbital/spin basis.
- Polarization further selects components; forbidden means absent in this approximation, not impossible by all multiphoton or multipole mechanisms.
Sources · 1
References
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Evidence and review
Quantum Mechanics (2016): Electric dipole transitions: Equations 8.164–8.174: long-wavelength expansion and orbital/spin rules; forbidden-transition qualification in the next section.
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Entry details
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