Abstract
Hyperfine quantum-beat spectroscopy has been utilized in a pump-probe configuration to measure magnetic dipole (A) and electric quadrupole (B) coupling constants in the 3d and 3d levels of three isotopes of potassium. For many of these levels, the largest hyperfine splitting is smaller than the natural width, and so a subnatural linewidth technique is required. In the experiments, the 3d levels are excited on the 4d→3d quadrupole transition with linearly polarized light. Time evolution of the alignment components in the d levels is probed by time-delayed resonant radiation on the 3d→9p transitions. Comparison of the excitation rate for two orthogonal relative polarization directions of the pump and probe laser at each delay time permits derivation of a linear polarization degree. This quantity contains beats at the various hyperfine frequencies in the d levels. Fitting the experimentally obtained time dependence to theoretical expressions allows extraction of the hyperfine coupling constants. For the 3d level of we obtain A=0.96(4) MHz and B=0.37(8) MHz, indicating a typical precision also obtained for the other levels and isotopes.
- Received 21 October 1996
DOI:https://doi.org/10.1103/PhysRevA.55.3475
©1997 American Physical Society