Nuclear moments and isotope shifts of the actinide isotopes <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Cf</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>249</mml:mn><mml:mtext>–</mml:mtext><mml:mn>253</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> probed by laser spectroscopy

We report on high-resolution laser spectroscopy studies on $^{249\text{--}253}\mathrm{Cf}$ with spectral linewidths in the order of 100 MHz carried out at the RISIKO mass separator at Mainz University. In total three atomic ground-state transitions were investigated and the hyperfine parameters for the odd-$A$ isotopes and isotope shift for all examined isotopes have been determined from the measured spectra. The isotope shift measurements allowed tracking of changes in mean-squared charge radii across the deformed nuclear shell closure at $N=152$, whereby shape discontinuities were not observed. Experimental hyperfine coupling constants of the atomic ground state were combined with relativistic many-body atomic calculations to extract the nuclear magnetic-dipole moment of $^{249}\mathrm{Cf}$ with improved precision to ${\ensuremath{\mu}}_{I}{(}^{249}\mathrm{Cf})=\ensuremath{-}0.395(17){\ensuremath{\mu}}_{N}$, whereas ${\ensuremath{\mu}}_{I}{(}^{251}\mathrm{Cf})=\ensuremath{-}0.571(24){\ensuremath{\mu}}_{N}$ and ${\ensuremath{\mu}}_{I}{(}^{253}\mathrm{Cf})=\ensuremath{-}0.731(35){\ensuremath{\mu}}_{N}$ were derived for the first time. Additionally, the spectroscopic quadrupole moments ${Q}_{\mathrm{S}}{(}^{249}\mathrm{Cf})=6.27(33)\phantom{\rule{4pt}{0ex}}e\mathrm{b}$ and ${Q}_{\mathrm{S}}{(}^{253}\mathrm{Cf})=5.53(51)\phantom{\rule{4pt}{0ex}}e\mathrm{b}$ were extracted.