Exciton-Magnon Bound State in Mn${\mathrm{F}}_2$ and the Exciton Dispersion in Mn${\mathrm{F}}_2$ and RbMn${\mathrm{F}}_3$

The absorption of Mn${\mathrm{F}}_2$ in the 4000-Å region has been examined. Evidence is presented for the assignment of a sharp line at the edge of a magnon sideband to a magnon-exciton bound state.