| Alkaline earth atoms are laser excited in a static-electric field and probed using two experimental techniques: scaled energy recurrence spectroscopy and impulsive momentum retrieval. In scaled energy recurrence spectroscopy experiments, orbital dynamics of two-electron alkaline earth atoms in a static-electric field are studied. Specifically, photoabsorption spectra for Ba and Ca Rydberg atoms are measured as continuous functions of static-electric field and energy. In both atomic species, the laser excitation proceeds through the singly-excited nd series which are strongly perturbed by doubly-excited valence configurations. Clear signatures of the two-electron dynamics associated with these perturbing configurations are observed. In impulsive momentum retrieval (IMR) experiments, approximate momentum distributions of Rydberg electrons in static-electric fields are obtained using the IMR technique in conjunction with spatially sensitive detection, where an imaging detector enables the measurement of half-cycle pulse (HCP) ionization probability across the spatial profile of a focused HCP beam. By modulating the HCP amplitude [Zeibel and Jones, Phys. Rev. A 68, 023410 (2003)], we directly measure the derivative of the ionization vs. HCP impulse curve, enabling the recovery of momentum distributions with finer resolution than previously attainable. A thorough exploration of the HCP radiation utilized in these IMR experiments is also presented. Additionally, we develop a wave-packet method to simulate the effect that a finite HCP duration has on our measurements, and reasonable agreement between simulated and measured momentum distributions is obtained. Elements of both experimental techniques for probing Stark atoms are advanced in these studies. Furthermore, interesting properties of Stark atoms are demonstrated experimentally. |
