摘要
We report on a measurement of the transition amplitude ratio χ of an electric quadrupole ( E 2 ) to a magnetic dipole ( M 1 ) of the 6 P 1 / 2 → 6 P 3 / 2 transition in atomic thallium. We utilized the electromagnetically induced transparency mechanism and the sideband-bridging technique to resolve the isotopic transitions and their hyperfine manifold. Our measurement gave χ 205 = 0.2550 ( 20 ) ( 7 ) for 205 Tl, and χ 203 = 0.2532 ( 73 ) ( 7 ) for 203 Tl, which was measured for the first time. Our results provide a reference point for the theoretical calculation of atomic structures, and new input for the long dispute on the atomic thallium parity non-conservation measurements.