Experimental investigation of excited states in atomic dysprosium

A pair of closely lying states of opposite parity and the same total electronic angular momentum (J=10) at 19797.96 ${\mathrm{cm}}^{\mathrm{-}1}$ in dysprosium is experimentally investigated with the goal of evaluating parameters relevant to parity and parity–time-reversal violation experiments. An atomic beam apparatus is used. The states of interest are populated with a sequence of two laser pulses, and a third laser pulse and fluorescence detection are used to probe the state population. Their lifetimes are determined from the dependence of the fluorescence signal on the time delay between the pump and probe pulses. The lifetime of the even-parity state was also measured by a different method involving detection of cascade fluorescence. Spectroscopy of radio-frequency E1 transitions between the opposite-parity states is performed when one of the states is populated and the population of the other is probed. This determines precise energy separations between various isotope and hyperfine structure components, and allows extraction of the corresponding isotope shift and hyperfine structure parameters. Electric polarizability is determined from radio-frequency line shapes in the presence of a dc electric field. As part of the preparation of a parity violation experiment, level-crossing signals which occur when various Zeeman components of the closest hyperfine components (isotope 163, F=10.5; initial separation 3.1 MHz) are brought together in the presence of collinear electric and magnetic fields were studied. These measurements provide an independent determination of the E1 matrix element between the opposite-parity states. In addition, lifetimes, isotope, and hyperfine structure of other dysprosium states are obtained and a number of narrow autoionization resonances (Γ<10 ${\mathrm{cm}}^{\mathrm{-}1}$) are observed.