Doublet term
= Doublet term
{title2=$S=1/2,\quad{}^2L$}
An <atomic term> with total <spin> one half and spin multiplicity two. A doublet S term has only J=1/2, while a doublet with nonzero L can have J=L-1/2 and J=L+1/2. Spin multiplicity therefore need not equal the number of resolved <spectral lines>.