Hyperfine structure of electronic levels and the first measurement of the nuclear magnetic moment of

Laser resonant photoionization spectroscopy was used to study the hyperfine structure of the optical $3d^{8}4s^{2} {}^{3}F_{4}\rightarrow 3d^{8}4s4p {}^{3}G^{\rm o}_{3}$ and $3d^{9}4s {}^{3}D_{3}\rightarrow 3d^{8}4s4p {}^{3}G^{\rm o}_{3}$ transitions of 63Ni and 61Ni isotopes. Experimental spectra allowed us to derive hyperfine interaction constants and determine the magnetic dipole moment of the nuclear ground state of 63Ni for the first time: $\mu=+0.496(5)\mu_{\rm N}$. The value obtained agrees well with the prediction of the self-consistent theory of finite Fermi systems