Hyperfine Structure and Isotope Shift in Er I by the Atomic-Beam Laser Spectroscopy

Abstract

Isotope shifts of 5 transitions from the 3 H 6 and 3 F 4 levels of the ground configuration 4 f 12 6 s 2 in Er I were measured for the stable isotopes with A =162-170 by the atomic-beam laser spectroscopy. Hyperfine constants A and B of 7 atomic levels were determined. Changes of mean square nuclear charge radii δ< r 2 > and mean square nuclear deformation parameters δ<β 2 > were deduced. The deformations of 164-170 Er were found to be mainly quadrupole and contributions of higher order deformation parameters for 162 Er were estimated. J -dependence of isotope shifts in the (6, 1) term of 4 f 12 6 s 6 p was found. It is concluded that the J -dependence was caused by the crossed-second-order effect in which the field shift has dominant contribution.