Nuclear structure investigations of 253−255 Es by laser spectroscopy

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 groundstate 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.