Abstract
Laser resonance ionization spectroscopy was performed on the rare einsteinium isotopes 253−255Es at the RISIKO mass separator in Mainz. With low sample sizes ranging down to femtograms, the prominent 352 nm-ground-state transition was measured in all three einsteinium isotopes, and four additional ground-state transitions were measured in 254Es. Hyperfine-structure analysis resulted in assigned spin values of I(254Es)=7 and I(255Es)=7/2. From the extracted coupling constants, nuclear magnetic dipole moments of μI(254Es)=3.42(7)μN and μI(255Es)=4.14(10)μN as well as spectroscopic electric quadrupole moments of Qs(254Es)=9.6(1.2)eb and Qs(255Es)=5.1(1.7)eb were derived. Our value for 254Es deviates from the value of ∣∣μI(254Es)∣∣=4.35(41)μN extracted from the angular anisotropy of α-radiation emitted by 254Es.
