Diode-laser hyperfine-structure spectroscopy of La-138,La-139 - art. no. 064501

With a beam of unenriched lanthanum, the hyperfine structure (hfs) of La-13 8,La-139 has been measured for the transition from the 5d6s(2) D-2(3/2) gro und state to the 5d6s6p F-4(5/2) level at 675.304 nm by means of atomic-bea m diode-laser spectroscopy. Magnetic-dipole (A) and electric-quadrupole (B) hfs constants of the 0.090% abundant La-138, as well as those of La-139, h ave been determined for the 5d6s(2) D-2(3/2) and 5d6s6p F-4(5/2) levels; th is serves as a measurement of hyperfine structure constants A and B for La- 138. The isotope shift between La-139 and La-138 has been obtained for the 675.304-nm transition and change in mean-square nuclear charge radii delta <r(2)> derived.