Paschen-Back transition-channel count
= Paschen-Back transition-channel count
{c}
For a one-electron P-to-S transition with <nuclear spin> zero, ten electric-dipole sublevel channels have finite strength at weak nonzero field. Six retain finite strength in the complete orbital-spin decoupling limit. Channel count is distinct from spectral <frequency> count: retaining first-order residual <spin-orbit interaction> <energy> gives five distinct frequencies, with two central channels degenerate.