The helium line at is emitted when helium's excited electron drops from a level ( )…
PHYSICS · Multi-part · Fermi University Physics · Atomic, Molecular & Optical Physics · Radiative transitions, external fields and collisions · Radiative transitions, external fields and collisions
Reading the Spectrum, Ch Atoms in a magnetic field: moments, the Zeeman effect and the Paschen-Back limit
Problem
The helium line at 501.6nm is emitted when helium's excited electron drops from a p level (L=1) to an s level (L=0). In both levels the spins of helium's two electrons cancel, so the levels carry no net spin moment and the orbital picture of the normal Zeeman triplet applies without complication from spin. The atoms sit in a uniform field B=0.80T.
((a)) State how many spectral-line positions are predicted, and name the polarisation of each seen (i) looking across the field and (ii) looking along the field.
((b)) Calculate the wavelength separation Δλ between each outer component and the unshifted line position.