Axial spin-three-halves resonance coincidence
= Axial spin-three-halves resonance coincidence
{title2=$h\nu=D$}
For $H=DS_z^2+g\mu_BBS_z$ with $D>0$ and a transverse oscillating field, the allowed gaps are $g\mu_BB$, $|g\mu_BB-2D|$ and $g\mu_BB+2D$. Below $h\nu=2D$, the positive-field solutions are $h\nu$, $2D-h\nu$ and $2D+h\nu$ in units of $g\mu_BB$. At $h\nu=D$ two transitions coincide, leaving two distinct resonance fields. At $h\nu=2D$ a zero-field resonance must be counted separately.