Cadmium's resonance line is the electric-dipole transition

PHYSICS · Multi-part · Fermi University Physics · Atomic, Molecular & Optical Physics · Radiative transitions, external fields and collisions · Radiative transitions, external fields and collisions

Deriving the Spectrum, Ch Radiative transitions and lifetimes

Problem

Cadmium's 228.8 nm228.8\,\mathrm{nm} resonance line is the electric-dipole transition 5s5p 1P1→5s2 1S05s5p\,{}^1P_1 \to 5s^2\,{}^1S_0. A weak magnetic field B⃗\vec B is applied along z^\hat z, splitting the upper level into M=−1,0,+1M=-1,0,+1 while the lower level, with J=0J=0, has only M=0M=0. ((a)) List the allowed ΔM\Delta M values for the emitted light, and explain why the M=0→M=0M=0\to M=0 component is allowed even though a J=0→J′=0J=0\to J'=0 transition is forbidden. ((b)) Predict what is seen looking along z^\hat z (light travelling along the field direction): how many spectral components, and what polarisation. ((c)) Predict what is seen looking perpendicular to z^\hat z: how many components, and what polarisation each has.

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