Question

State, with reasons, which of the following transitions are forbidden for electric dipole transitions 

³D₁ → ²F₃ 

²P_3/2 → ²S_1/2 

²P_1/2 → ²S_1/2 

³D₂ → ³S₁

Answer 1

According to Laporte rule, transitions via dipole radiation are forbidden between atomic states with the same parity. This is because dipole moment has odd parity and the integral

 

(dipole moment) ψ_idτ will vanish between symmetric limits because the integrand will be odd when ψ_i and ψ_f have the same parity. Now the parity of the state is determined by the factor (−1)^l. Thus for the given terms the l-values and the parity are as below