LA-138, LA-139 NUCLEAR ELECTRIC-QUADRUPOLE-MOMENT RATIO BY LASER-RF DOUBLE-RESONANCE

The laser-rf double-resonance technique has been used to obtain 1-ppm measurements of the largest hyperfine intervals in the ground (5d6s2 D322) and first excited (5d6s2 D522) atomic levels of 0.09% abundant La138 with a beam of unenriched lanthanum. The hfs ratios A138A139 and B138B139 are thereby obtained. The former shows a 0.36% hyperfine anomaly with respect to the NMR ratio of the nuclear g factors. The uncertainty in the new value B138B139=+2.27±0.04 arises from uncertainties in interpreting the hyperfine-anomaly effects observed. The La138,139 isotope shift is evaluated for both of the lines studied. © 1979 The American Physical Society.