We report reversible hole burning in the inhomogeneously broadened zero-phonon line of F3+ in NaF at 5456. The hole recovery time shows two components: 2.5 sec assigned to triplet-state relaxation and 70 min assigned to electron tunneling from an adjacent center. These holes were used to measure the homogeneous linewidth (17 MHz) and the linear Stark effect. We find the excited E1 level has a distribution of zero-field splittings inside the inhomogeneous lines, which quenches the first-order Zeeman effect. © 1979 The American Physical Society.